Chemistry Concepts and Scientific Method

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Questions and Answers

When balanced, what is the coefficient for PbCO3 in the equation Pb(NO3)2 + K2CO3 → PbCO3 + KNO3?

  • 4
  • 1 (correct)
  • 2
  • 3

What is the coefficient of NaI in the balanced equation Na2S2O3 + I2 → NaI + Na2S4O6?

  • 2 (correct)
  • 6
  • 4
  • 3

What is the correct coefficient for H2O in the balanced equation CH3OH + O2 → CO2 + H2O?

  • 1
  • 4
  • 3
  • 2 (correct)

In the equation NO2 + H2O → HNO3 + NO, what is the coefficient in front of HNO3 when balanced?

<p>1 (C)</p> Signup and view all the answers

What is the coefficient for MnCl2 when the reaction MnO2 + HCl → MnCl2 + Cl2 + H2O is balanced?

<p>1 (B)</p> Signup and view all the answers

Which of the following is not a clue that a chemical reaction has occurred?

<p>The reactant is smaller. (A)</p> Signup and view all the answers

What does the equation $N_2 + 3H_2 → 2NH_3$ imply about the mass of the reacting substances?

<p>The total mass of reactants equals the total mass of products. (B)</p> Signup and view all the answers

How many of the following ways are correct methods to balance the equation $H_2 + O_2 → H_2O$? I. $2H_2 + O_2 → 2H_2O$ II. $H_2 + O_2 → H_2O$ III. $4H_2 + 2O_2 → 4H_2O$ IV. $H_2 + O_2 → H_2O_2$

<p>3 (C)</p> Signup and view all the answers

What is the balanced equation for the reaction of solid aluminum oxide with gaseous carbon monoxide to produce aluminum and carbon dioxide?

<p>Al2O3 + 3CO → 2Al + 3CO2 (A)</p> Signup and view all the answers

Which of the following is not a product formed from the reaction of aluminum oxide and carbon monoxide?

<p>Aluminum oxide (D)</p> Signup and view all the answers

What is the sum of the coefficients in the balanced equation LiAlH4 + AlCl3 → AlH3 + LiCl?

<p>11 (A)</p> Signup and view all the answers

Which of the following statements about balancing a chemical equation is true?

<p>Coefficients are used to balance different chemical substances. (B)</p> Signup and view all the answers

In the equation N2 + O2 → N2O3, what is the correct coefficient required for balancing?

<p>3 (C)</p> Signup and view all the answers

Is it possible to use fractions as coefficients when balancing a chemical equation?

<p>Yes, always. (B)</p> Signup and view all the answers

What does c/d represent in the equation aA + bB → cC + dD?

<p>The ratio of coefficients in the balanced equation. (C)</p> Signup and view all the answers

In the reaction KClO3 → KCl + KClO4, what is the coefficient in front of KCl when the equation is balanced using the smallest possible integers?

<p>3 (C)</p> Signup and view all the answers

What is the required coefficient for NaOH in the balanced equation NBr3 + NaOH → N2 + NaBr + HOBr?

<p>2 (C)</p> Signup and view all the answers

When balancing the equation C6H14 + O2 → CO2 + H2O, what is the coefficient in front of O2?

<p>19 (C)</p> Signup and view all the answers

In the equation MgCl2 + K3PO4 → Mg3(PO4)2 + KCl, how many moles of K3PO4 are needed to balance the reaction?

<p>2 (D)</p> Signup and view all the answers

What is the correct coefficient for H2O when balancing the equation Mg(OH)2(aq) + HBr(aq) → MgBr2(aq) + H2O(l)?

<p>2 (D)</p> Signup and view all the answers

What is the total number of oxygen atoms in the balanced equation 2KClO3(s) → 2KCl(s) + 3O2(g)?

<p>6 (D)</p> Signup and view all the answers

In the reaction Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(s), how many moles of carbon monoxide are required?

<p>3 (A)</p> Signup and view all the answers

What coefficient should be placed in front of H2O when balancing the equation 2NO(g) + 2H2(g) → N2(g) + ?

<p>2 (D)</p> Signup and view all the answers

What is the balanced coefficient of H2O in the reaction Ca(s) + 2H2O(l) → Ca(OH)2(aq) + ?

<p>2 (D)</p> Signup and view all the answers

In the balanced reaction 2H2S(g) + 3O2(g) → 2SO2(g) + 2H2O(g), what is the stoichiometric ratio of H2S to SO2?

<p>2 (C)</p> Signup and view all the answers

How many moles of CO2 are produced in the reaction Fe2O3(s) + CO(g) → 2FeO(s) + CO2(s)?

<p>1 (B)</p> Signup and view all the answers

Which coefficient is placed before HCl in the balanced equation SiCl4 + H2O → SiO2 + HCl?

<p>2 (C)</p> Signup and view all the answers

Which of the following represents the balanced form of the equation for the reaction of potassium iodide with chlorine gas?

<p>2KI(aq) + Cl2(g) → 2KCl(aq) + I2(s) (B)</p> Signup and view all the answers

For the reaction of magnesium nitride with water to produce ammonia and magnesium hydroxide, what is the correctly balanced equation?

<p>Mg3N2(s) + 6H2O(l) → 3NH3(g) + Mg(OH)2(s) (A)</p> Signup and view all the answers

What is the balanced equation for the reaction of calcium with oxygen to form calcium oxide?

<p>2Ca(s) + O2(g) → 2CaO(s) (B)</p> Signup and view all the answers

In the reaction of sodium with water, which balanced equation correctly represents the products formed?

<p>2Na(s) + 2H2O(l) → H2(g) + 2NaOH(aq) (A)</p> Signup and view all the answers

Which of the following is the correctly balanced chemical equation for the reaction of sugar with oxygen to produce carbon dioxide and water?

<p>C3H7OH(l) + 9O2(g) → 6CO2(g) + 8H2O(g) (C)</p> Signup and view all the answers

What is the correct balanced equation for the reaction of magnesium with oxygen?

<p>2Mg(s) + O2(g) → 2MgO(s) (B)</p> Signup and view all the answers

When balancing the equation BaCl2(aq) + H2SO4(aq) → BaSO4(s) + HCl(aq), what is the correct coefficient for HCl?

<p>2 (B)</p> Signup and view all the answers

In the balanced equation Sb(s) + O2(g) → Sb2O5(s), what is the coefficient for Sb when fully balanced?

<p>2 (B)</p> Signup and view all the answers

What is the correct coefficient for O2 in the balanced reaction C4H10(g) + O2(g) → CO2(g) + H2O(g)?

<p>8 (C)</p> Signup and view all the answers

In the combustion reaction CH3OH(l) + O2(g) → CO2(g) + H2O(g), how many moles of H2O are produced?

<p>2 (C)</p> Signup and view all the answers

What is the coefficient for KNO3 in the balanced equation Pb(NO3)2(aq) + K2CrO4(aq) → PbCrO4(s) + KNO3(aq)?

<p>2 (C)</p> Signup and view all the answers

In the equation (NH4)2Cr2O7(s) → N2(g) + H2O(g) + Cr2O3(s), what is the coefficient of H2O when fully balanced?

<p>4 (A)</p> Signup and view all the answers

Which statement about subscripts in a chemical equation is accurate?

<p>Subscripts indicate the number of atoms in a molecule. (D)</p> Signup and view all the answers

What is the balanced form of the reaction for calcium metal with oxygen gas producing calcium oxide?

<p>2Ca(s) + O2(g) → 2CaO(s) (D)</p> Signup and view all the answers

In the balanced equation for the reaction of potassium metal with water, what does the final product consist of?

<p>Potassium hydroxide and hydrogen gas (B)</p> Signup and view all the answers

What is the coefficient in front of NaOH when balancing the equation 2Na + 2H2O → 2NaOH + H2?

<p>2 (B)</p> Signup and view all the answers

What is the coefficient for K2CO3 in the balanced equation Pb(NO3)2 + K2CO3 → PbCO3 + KNO3?

<p>1 (B)</p> Signup and view all the answers

In balancing the equation Al + Fe3O4 → Al2O3 + Fe, what is the coefficient of Al?

<p>6 (B)</p> Signup and view all the answers

What will be the coefficient for H2O in the balanced equation CH3OH + O2 → CO2 + H2O?

<p>5 (A)</p> Signup and view all the answers

When balancing the equation P4O10 + H2O → H3PO4, what is the coefficient for H3PO4?

<p>1 (C)</p> Signup and view all the answers

What is the sum of the coefficients when balancing the equation LiAlH4(s) + AlCl3(s) → AlH3(s) + LiCl(s)?

<p>9 (C)</p> Signup and view all the answers

In the equation aA + bB → cC + dD, how many distinct values can be assigned to c/d?

<p>1 (A)</p> Signup and view all the answers

Which statement is accurate regarding the use of coefficients when balancing a chemical equation?

<p>Fractions can be used as coefficients. (A)</p> Signup and view all the answers

When the equation Pb(s) + AgNO3(aq) → Pb(NO3)2 + Ag(s) is balanced, what will be the coefficient of Ag?

<p>2 (C)</p> Signup and view all the answers

What misconception about balancing chemical equations is highlighted by the statement 'The subscripts in the reactants must be maintained in the products'?

<p>Subscripts do not impact the products. (B)</p> Signup and view all the answers

What does the equation $N_2 + 3H_2 → 2NH_3$ indicate about the relationship between the masses of the reacting substances?

<p>Mass is conserved in the reaction (A)</p> Signup and view all the answers

How many correct methods are there to balance the equation $H_2 + O_2 → H_2O$?

<p>3 (D)</p> Signup and view all the answers

Which of the following is the balanced equation for the reaction of solid aluminum oxide with carbon monoxide?

<p>$Al_2O_3 + 3CO → 2Al + 3CO_2$ (C)</p> Signup and view all the answers

Which of the following equations represents a situation where mass is not conserved?

<p>$N_2 + O_2 → 2NO$ (C)</p> Signup and view all the answers

What is the correct coefficient for $O_2$ when balancing the reaction $C_6H_{14} + O_2 → CO_2 + H_2O$?

<p>19 (C)</p> Signup and view all the answers

When balancing the equation $NaBH_4 + BF_3 → NaBF_4 + B_2H_6$, how many moles of $NaBH_4$ are needed?

<p>3 (D)</p> Signup and view all the answers

What is the coefficient for $K_3PO_4$ when balancing the equation $MgCl_2 + K_3PO_4 → Mg_3(PO_4)_2 + KCl$?

<p>2 (A)</p> Signup and view all the answers

In the balanced equation for $As_2O_3 + Ca(OH)_2 → Ca_3(AsO_4)_2 + H_2O$, how many moles of $Ca(OH)_2$ are there?

<p>2 (B)</p> Signup and view all the answers

When balancing the equation $Sb(s) + O_2(g) → Sb_2O_3(s)$, what is the coefficient in front of $Sb$?

<p>2 (C)</p> Signup and view all the answers

What is the correct coefficient for O2 when balancing the equation $KClO3(s) \rightarrow KCl(s) + O2(g)$?

<p>2 (C)</p> Signup and view all the answers

When the equation $2NO(g) + 2H2(g) \rightarrow N2(g) + ?$ is balanced, what is the coefficient in front of H2O?

<p>2 (D)</p> Signup and view all the answers

What is the required coefficient for HCl when balancing the equation $SiCl4 + H2O \rightarrow SiO2 + HCl$?

<p>4 (C)</p> Signup and view all the answers

In the balanced reaction $Fe2O3(s) + ?CO(g) \rightarrow 2FeO(s) + CO2(s)$, what is the coefficient in front of CO?

<p>3 (B)</p> Signup and view all the answers

What is the coefficient in front of H2O in the balanced equation $Ca(s) + 2H2O(l) \rightarrow Ca(OH)2(aq) + ?$?

<p>1 (D)</p> Signup and view all the answers

When balancing the equation $2H2S(g) + 3O2(g) \rightarrow ?SO2(g) + 2H2O(g)$, what is the coefficient in front of SO2?

<p>2 (D)</p> Signup and view all the answers

To balance the equation $Cu(s) + 2H2SO4(aq) \rightarrow ?CuSO4(aq) + SO2(g) + ?H2O(l)$, what is the coefficient for CuSO4?

<p>1 (D)</p> Signup and view all the answers

What is the balanced equation for the reaction of magnesium nitride with water to produce ammonia and magnesium hydroxide?

<p>Mg3N2 + 6H2O → 2NH3 + 3Mg(OH)2 (C)</p> Signup and view all the answers

Which of the following correctly balances the equation for the reaction of sodium with water?

<p>2Na + H2O → H2 + 2NaOH (D)</p> Signup and view all the answers

What is the correct balanced equation for the reaction of calcium carbonate with hydrochloric acid?

<p>CaCO3 + 2HCl → H2O + CO2 + CaCl2 (B)</p> Signup and view all the answers

In the balanced equation for the reaction of phosphorus tribromide with water, what are the correct coefficients?

<p>PBr3 + H2O → H3PO3 + HBr (D)</p> Signup and view all the answers

What is the balanced equation for the reaction of iron(II) nitrate with hydrogen sulfide?

<p>Fe(NO3)2 + H2S → FeS + HNO3 (D)</p> Signup and view all the answers

What is the coefficient of Sb in the balanced equation Sb(s) + O2(g) → Sb2O5(s)?

<p>4 (C)</p> Signup and view all the answers

Which coefficient is correct for O2 in the balanced reaction of C4H10(g) + O2(g) → CO2(g) + H2O(g)?

<p>8 (A)</p> Signup and view all the answers

In the balanced equation CH3OH(l) + O2(g) → CO2(g) + H2O(g), what is the coefficient of H2O?

<p>2 (D)</p> Signup and view all the answers

What coefficient for KNO3 is required to balance the equation Pb(NO3)2(aq) + K2CrO4(aq) → PbCrO4(s) + KNO3(aq)?

<p>2 (A)</p> Signup and view all the answers

When balancing the equation (NH4)2Cr2O7(s) → N2(g) + H2O(g) + Cr2O3(s), what is the coefficient for H2O?

<p>4 (D)</p> Signup and view all the answers

What is the coefficient of HCl in the balanced equation BaCl2(aq) + H2SO4(aq) → BaSO4(s) + HCl(aq)?

<p>2 (B)</p> Signup and view all the answers

In the reaction of calcium metal and oxygen gas to produce calcium oxide, what is the final balanced equation?

<p>2Ca(s) + O2(g) → 2CaO(s) (D)</p> Signup and view all the answers

What is the coefficient for Al in the balanced equation 2Al(s) + 3I2(s) → 2AlI3(s)?

<p>2 (A)</p> Signup and view all the answers

Which statement about balancing a chemical equation is incorrect?

<p>All subscripts must be conserved. (A)</p> Signup and view all the answers

In the balanced equation for the reaction of potassium metal with water, what is the final product formed?

<p>Potassium hydroxide (A)</p> Signup and view all the answers

What is the coefficient for O2 when balancing the equation C6H14 + O2 → CO2 + H2O?

<p>19 (C)</p> Signup and view all the answers

When balancing the equation KClO3 → KCl + KClO4, what is the coefficient for KCl when written in smallest integers?

<p>3 (D)</p> Signup and view all the answers

What is the correct coefficient for NaOH in balancing the equation NBr3 + NaOH → N2 + NaBr + HOBr?

<p>4 (C)</p> Signup and view all the answers

In the balanced equation MgCl2 + K3PO4 → Mg3(PO4)2 + KCl, how many moles of K3PO4 are necessary?

<p>2 (A)</p> Signup and view all the answers

What is the coefficient of H2O in the balanced equation Mg(OH)2 + 2HBr → MgBr2 + 2H2O?

<p>2 (C)</p> Signup and view all the answers

What is the correct coefficient when balancing the equation Pb(s) + AgNO3(aq) → Pb(NO3)2 + Ag(s)?

<p>2 (B)</p> Signup and view all the answers

What coefficient should be placed in front of O2 when balancing the equation S(s) + O2(g) → SO2(g)?

<p>1 (B)</p> Signup and view all the answers

When balancing the reaction N2(g) + O2(g) → N2O3, what is the correct coefficient for N2 when fully balanced?

<p>2 (B)</p> Signup and view all the answers

What is the sum of the coefficients in the balanced form of the equation Al2O3(s) + H2SO4(aq) → Al2(SO4)3(aq) + H2O(l)?

<p>10 (A)</p> Signup and view all the answers

In the equation 2H2 + O2 → 2H2O, how many molecules of H2O are formed when fully balanced?

<p>2 (A)</p> Signup and view all the answers

Which of the following observations is NOT a clue that a chemical reaction has occurred?

<p>The reactant is smaller. (A)</p> Signup and view all the answers

What does the equation $N_2 + 3H_2 → 2NH_3$ imply about the relative masses of the reacting substances?

<p>The total mass of products is equal to the total mass of reactants. (A)</p> Signup and view all the answers

How many correct methods to balance the equation $H_2 + O_2 → H_2O$ are identified in the given options?

<p>1 (B)</p> Signup and view all the answers

What is the balanced equation for the reaction of solid aluminum oxide with gaseous carbon monoxide?

<p>Al2O3(s) + 3CO(g) → 2Al(s) + 3CO2(g) (D)</p> Signup and view all the answers

Which of the following is true regarding the chemical reaction products of aluminum oxide and carbon monoxide?

<p>Carbon dioxide gas is produced. (C)</p> Signup and view all the answers

When balancing the equation $Na2S2O3 + I2 → NaI + Na2S4O6$, what is the correct coefficient in front of NaI?

<p>2 (B)</p> Signup and view all the answers

In the balanced equation $Pb(NO3)2 + K2CO3 → PbCO3 + KNO3$, what coefficient corresponds to KNO3?

<p>2 (C)</p> Signup and view all the answers

What is the coefficient for Al when balancing the equation $Al + Fe3O4 → Al2O3 + Fe$?

<p>3 (B)</p> Signup and view all the answers

What is the coefficient in front of H2O for the balanced equation $CH3OH + O2 → CO2 + H2O$?

<p>2 (C)</p> Signup and view all the answers

In the reaction $MnO2 + HCl → MnCl2 + Cl2 + H2O$, which coefficient should be placed in front of HCl when balanced?

<p>3 (A)</p> Signup and view all the answers

What is the correct balanced equation for the reaction of potassium iodide with chlorine gas?

<p>2KI(aq) + Cl2(g) → KCl(aq) + I2(s) (D)</p> Signup and view all the answers

Which of the following represents the correct coefficients for the balanced equation of magnesium nitride reacting with water to produce ammonia and magnesium hydroxide?

<p>Mg3N2(s) + 6H2O(l) → 2NH3(g) + 3Mg(OH)2(s) (A)</p> Signup and view all the answers

In the balanced equation for the reaction of calcium with oxygen to form calcium oxide, what are the correct coefficients?

<p>2Ca(s) + O2(g) → 2CaO(s) (C)</p> Signup and view all the answers

What is the balanced form of the equation for the reaction of sodium with water?

<p>2Na(s) + 2H2O(l) → H2(g) + 2NaOH(aq) (A)</p> Signup and view all the answers

In the combustion reaction $C3H7OH + O2 → CO2 + H2O$, what are the correct coefficients for the balanced equation?

<p>2C3H7OH(l) + 6O2(g) → 6CO2(g) + 8H2O(g) (A)</p> Signup and view all the answers

What is the coefficient in front of SiO2 when balancing the equation SiCl4 + H2O → SiO2 + HCl?

<p>4 (C)</p> Signup and view all the answers

In the reaction H2O2(l) → H2O(l) + O2(g), what is the coefficient of H2O when balanced?

<p>2 (C)</p> Signup and view all the answers

What is the number in front of O2 when balancing the equation KClO3(s) → KCl(s) + O2(g)?

<p>2 (A)</p> Signup and view all the answers

When balancing the equation Cu(s) + H2SO4(aq) → CuSO4(aq) + SO2(g) + H2O(l), what is the coefficient in front of H2O?

<p>2 (C)</p> Signup and view all the answers

When balancing the equation Fe2O3(s) + 3CO(g) → 2FeO(s) + CO2(s), what is the correct coefficient for CO2?

<p>1 (A)</p> Signup and view all the answers

What is the correct coefficient for H2 in the balanced equation 2H2 + O2 → 2H2O?

<p>2 (A)</p> Signup and view all the answers

What is the correct coefficient for HCl when balancing the equation BaCl2(aq) + H2SO4(aq) → BaSO4(s) + HCl(aq)?

<p>2 (C)</p> Signup and view all the answers

Which coefficient is needed for O2 in the balanced equation C4H10(g) + O2(g) → CO2(g) + H2O(g)?

<p>8 (A)</p> Signup and view all the answers

Which of the following represents the correct coefficient for H2O when balancing the equation (NH4)2Cr2O7(s) → N2(g) + H2O(g) + Cr2O3(s)?

<p>4 (B)</p> Signup and view all the answers

What is the correct coefficient for KNO3 in the balanced equation Pb(NO3)2(aq) + K2CrO4(aq) → PbCrO4(s) + KNO3(aq)?

<p>2 (B)</p> Signup and view all the answers

In the equation CH3OH(l) + O2(g) → CO2(g) + H2O(g), what is the coefficient for CO2 when fully balanced?

<p>2 (C)</p> Signup and view all the answers

What is the coefficient for H2O in the balanced equation 2C4H10(g) + O2(g) → CO2(g) + H2O(g)?

<p>10 (A)</p> Signup and view all the answers

In the reaction (NH4)2Cr2O7(s) → N2(g) + H2O(g) + Cr2O3(s), what is the coefficient of N2 when fully balanced?

<p>1 (A)</p> Signup and view all the answers

Which coefficient would be correct for the reaction of potassium metal with water to form potassium hydroxide and hydrogen gas?

<p>2 (D)</p> Signup and view all the answers

What is the coefficient of oxygen gas (O2) in the balanced equation for the combustion of methanol CH3OH?

<p>3 (B)</p> Signup and view all the answers

What is the sum of the coefficients when balancing the equation Pb(s) + AgNO3(aq) → Pb(NO3)2 + Ag(s)?

<p>4 (D)</p> Signup and view all the answers

In the reaction N2(g) + O2(g) → N2O3, how many total moles of gas are reacting on the left side of the equation?

<p>2 (B)</p> Signup and view all the answers

When balancing the equation Al2O3(s) + H2SO4(aq) → Al2(SO4)3(aq) + H2O(l), what coefficient should be placed in front of H2SO4?

<p>2 (B)</p> Signup and view all the answers

In the equation S(s) + O2(g) → SO2(g), what is the required coefficient for O2 when balanced?

<p>2 (B)</p> Signup and view all the answers

Which of the following statements describes a requirement when balancing the reaction aA + bB → cC + dD?

<p>Coefficients must maintain the law of conservation of matter. (A)</p> Signup and view all the answers

Which of the following statements correctly identifies a sign of a chemical reaction occurring?

<p>A solid precipitate is formed. (A)</p> Signup and view all the answers

What implication does the equation $N_2 + 3H_2 → 2NH_3$ have regarding the mass of the substances involved?

<p>The mass of products is equal to the mass of the reactants. (D)</p> Signup and view all the answers

How many of the following ways are valid methods to balance the equation $H_2 + O_2 → H_2O$? I. $2H_2 + O_2 → 2H_2O$ II. $H_2 + O_2 → H_2O$ III. $4H_2 + 2O_2 → 4H_2O$ IV. $H_2 + O_2 → H_2O_2$

<p>3 (B)</p> Signup and view all the answers

What is the balanced equation for the reaction of aluminum oxide with carbon monoxide to produce aluminum and carbon dioxide?

<p>Al2O3(s) + 3CO(g) → 2Al(s) + 3CO2(g) (B)</p> Signup and view all the answers

In the equation $N_2 + 3H_2 → 2NH_3$, which of the following statements regarding the reactants is false?

<p>One molecule of $N_2$ produces two grams of $NH_3$. (A)</p> Signup and view all the answers

What is the coefficient for NaOH when balancing the equation 2Na + 2H2O → 2NaOH + H2?

<p>2 (C)</p> Signup and view all the answers

In the balanced reaction MnO2 + HCl → MnCl2 + Cl2 + H2O, what is the coefficient in front of Cl2?

<p>4 (D)</p> Signup and view all the answers

What will be the coefficient for NaI when balancing the equation Na2S2O3 + I2 → NaI + Na2S4O6?

<p>2 (A)</p> Signup and view all the answers

What is the coefficient in front of CO2 when the equation C2H6 + O2 → CO2 + H2O is balanced using the smallest possible integers?

<p>5 (D)</p> Signup and view all the answers

What coefficient is required in front of HCl when balancing the equation SiCl4 + H2O → SiO2 + HCl?

<p>4 (C)</p> Signup and view all the answers

In the balanced equation KClO3(s) → KCl(s) + O2(g), what is the coefficient in front of KClO3?

<p>2 (C)</p> Signup and view all the answers

What is the coefficient for H2O in the balanced equation Ca(s) + H2O(l) → Ca(OH)2(aq) + H2(g)?

<p>2 (B)</p> Signup and view all the answers

When balancing the equation 2H2S(g) + O2(g) → SO2(g) + H2O(g), how many moles of O2 are required?

<p>3 (C)</p> Signup and view all the answers

What coefficient should be placed in front of CO in the equation Fe2O3(s) + CO(g) → FeO(s) + CO2(s) when balanced?

<p>2 (C)</p> Signup and view all the answers

In the balanced equation for the reaction of copper (Cu) with sulfuric acid (H2SO4), what is the coefficient for H2O?

<p>2 (B)</p> Signup and view all the answers

When the equation NaBH4 + BF3 → NaBF4 + B2H6 is balanced, what is the coefficient in front of NaBH4?

<p>3 (A)</p> Signup and view all the answers

What is the coefficient for K3PO4 in the balanced equation MgCl2 + K3PO4 → Mg3(PO4)2 + KCl?

<p>2 (C)</p> Signup and view all the answers

In the balanced equation As2O3 + Ca(OH)2 → Ca3(AsO4)2 + H2O, what is the coefficient in front of Ca(OH)2?

<p>3 (D)</p> Signup and view all the answers

What is the coefficient of BF3 in the balanced equation 3NaBH4 + 4BF3 → 3NaBF4 + 2B2H6?

<p>4 (D)</p> Signup and view all the answers

What is the correct coefficient of HCl in the balanced equation BaCl2(aq) + H2SO4(aq) → BaSO4(s) + ?

<p>2 (A)</p> Signup and view all the answers

What is the coefficient in front of O2 in the balanced reaction C4H10(g) + O2(g) → CO2(g) + H2O(g)?

<p>8 (D)</p> Signup and view all the answers

What is the coefficient of H2O when balancing the equation CH3OH(l) + O2(g) → CO2(g) + H2O(g)?

<p>2 (D)</p> Signup and view all the answers

In the equation (NH4)2Cr2O7(s) → N2(g) + ? + Cr2O3(s), what is the coefficient of H2O when fully balanced?

<p>4 (B)</p> Signup and view all the answers

When balancing the equation 2Ca(s) + O2(g) → ?CaO(s), what is the coefficient of CaO?

<p>2 (A)</p> Signup and view all the answers

In the reaction BaCl2(aq) + H2SO4(aq) → BaSO4(s) + ?, what is the correct coefficient for BaSO4?

<p>1 (C)</p> Signup and view all the answers

What is the coefficient for KNO3 when balancing Pb(NO3)2(aq) + K2CrO4(aq) → PbCrO4(s) + ?

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What is the correct coefficient of I2 when balancing the equation 2Al(s) + 3I2(s) → ?AlI3(s)?

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What is the coefficient of H2O in the balanced equation for the reaction CH4 + O2 → CO2 + H2O?

<p>2 (B)</p> Signup and view all the answers

What is the correct balanced equation for the reaction of sodium with water?

<p>2Na(s) + H2O(l) → H2(g) + NaOH(aq) (B)</p> Signup and view all the answers

When balancing the equation CaCO3(s) + HCl(aq) → H2O(l) + CO2(g) + CaCl2(aq), which of the following is true?

<p>CaCO3(s) + 2HCl(aq) → H2O(l) + CO2(g) + CaCl2(aq) (D)</p> Signup and view all the answers

What is the balanced coefficient for water in the combustion reaction of ethanol C2H5OH(l) + O2(g) → CO2(g) + H2O(g)?

<p>3H2O(g) (B)</p> Signup and view all the answers

For the balanced equation Mg3N2(s) + H2O(l) → NH3(g) + Mg(OH)2(s), how many water molecules are required?

<p>6H2O(l) (D)</p> Signup and view all the answers

Which equation correctly represents the balanced reaction between zinc and hydrochloric acid?

<p>Zn(s) + HCl(aq) → H2(g) + ZnCl2(aq) (B)</p> Signup and view all the answers

Flashcards

Clues of a chemical reaction

Changes like color change, formation of a solid, or bubbles forming, indicate a chemical reaction has occurred.

Stoichiometry equation meaning

The equation N2 + 3H2 → 2NH3 does NOT mean that 1 gram of nitrogen reacts with 3 grams of Hydrogen to form 2 grams of ammonia.

Balancing chemical equations

Adjusting the coefficients in a chemical equation to ensure equal numbers of each atom type on both sides.

Balanced equation (example)

The chemical equation that shows the correct proportion of substances (Al2O3(s) + 3CO(g) → 2Al(s) + 3CO2(g))

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Incorrect balancing method

Equation balancing that does not have an equal number of atoms of each type on both the reactant and product sides is incorrect.

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Coefficients in a Chemical Equation

Numbers placed in front of chemical formulas to balance the number of atoms of each element in a chemical equation.

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Balanced Equation for LiAlH4 + AlCl3 → AlH3 + LiCl

3LiAlH4 + 3AlCl3 → 3AlH3 + 3LiCl; coefficient sum = 12

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Why do we balance a chemical equation?

To ensure that the law of conservation of mass is followed in a chemical reaction.

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Possible Coefficients in Balanced Equation

Coefficients in a balanced chemical equation, like c and d in aA + bB → cC + dD, are whole integers or fractions that ensure a equal number of each atom on both sides of a reaction.

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Balanced Equation for Na + Hâ‚‚O

The balanced chemical equation for the reaction of sodium (Na) with water (Hâ‚‚O) to produce sodium hydroxide (NaOH) and hydrogen gas (Hâ‚‚).

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Coefficient of Sn in Sn + NaOH → Na₂SnO₂ + H₂

The number placed in front of a substance in a chemical equation to balance the number of atoms of each element on both sides.

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Coefficient of Na₂S₂O₃ in Na₂S₂O₃ + I₂ → NaI + Na₂S₄O₆

The number placed in front of Na₂S₂O₃ to balance the number of atoms of each element in the chemical equation.

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Coefficient of Pb(NO₃)₂ in Pb(NO₃)₂ + K₂CO₃ → PbCO₃ + KNO₃

The coefficient placed in front of Pb(NO₃)₂ to have equal number of atoms of each element in the chemical equation.

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Coefficient of Al in Al + Fe₃O₄ → Al₂O₃ + Fe

The number in front of Al in a balanced chemical equation to have equal number of atoms in reactants and products.

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Balancing Chemical Equations: C2H6 + O2 → CO2+H2O

Adjusting the coefficients in a chemical equation to ensure equal numbers of atoms of each element on both sides of the equation.

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Balancing Chemical Equations: NaBH4 + BF3 → NaBF4 + B2H6

The balanced chemical equation is 3NaBH4 + 4BF3 → 3NaBF4 + 2B2H6

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Balancing Chemical Equations: MgCl2 + K3PO4 → Mg3(PO4)2 + KCl

The balanced chemical equation is 3MgCl2 + 2K3PO4 → Mg3(PO4)2 + 6KCl

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Balancing Chemical Equations: C6H14 + O2 → CO2 + H2O

The balanced chemical equation is 2C6H14 + 19O2 → 12CO2 + 14H2O

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Balancing Chemical Equations: As2O3 + Ca(OH)2 → Ca3(AsO4)2 + H2O

The balanced chemical equation is As2O3 + 3Ca(OH)2 → Ca3(AsO4)2 + 3H2O

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Balance this equation: C2H6 + O2 → CO2 + H2O

Adjust the coefficients in front of each chemical formula to ensure an equal number of each type of atom on both sides of the equation. The smallest possible integers should be used.

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Balance this equation: SiCl4 + H2O → SiO2 + HCl

Adjust the coefficients in front of each chemical formula to ensure an equal number of each type of atom on both sides of the equation. The smallest possible integers should be used.

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Balance this equation: KClO3(s) → KCl(s) + O2(g)

Adjust the coefficients in front of each chemical formula to ensure an equal number of each type of atom on both sides of the equation. The smallest possible integers should be used.

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Write and balance the equation: Iron(III) oxide + carbon monoxide → iron metal + carbon dioxide

First, write the chemical formulas for each reactant (iron(III) oxide and carbon monoxide) and product (iron metal and carbon dioxide). Then, adjust the coefficients in front of each formula to ensure an equal number of atoms of each type on both sides of the equation.

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Write and balance the equation: Nitrogen monoxide gas + hydrogen gas → Nitrogen gas + water vapor

First, write the chemical formulas for each reactant (nitrogen monoxide and hydrogen gas) and product (nitrogen gas and water vapor). Then, adjust the coefficients in front of each formula to ensure an equal number of atoms of each type on both sides of the equation.

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Write and balance the equation: Calcium metal + water → aqueous calcium hydroxide + hydrogen gas

First, write the chemical formulas for each reactant (calcium metal and water) and product (aqueous calcium hydroxide and hydrogen gas). Then, adjust the coefficients in front of each formula to ensure an equal number of atoms of each type on both sides of the equation.

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Write and balance the equation: Copper metal + aqueous sulfuric acid → aqueous copper(II) sulfate + sulfur dioxide gas + water

First, write the chemical formulas for each reactant (copper metal and aqueous sulfuric acid) and product (aqueous copper(II) sulfate, sulfur dioxide gas, and water). Then, adjust the coefficients in front of each formula to ensure an equal number of atoms of each type on both sides of the equation.

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Balance this equation: KI + Cl2 → KCl + I2

Adjust the coefficients in front of each chemical formula to ensure the same number of each type of atom on both sides of the equation.

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What does balancing a chemical equation mean?

It means adjusting the coefficients in front of each chemical formula to make sure the number of atoms of each element is the same on both the reactant and product sides.

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Why is it important to balance chemical equations?

It ensures that the law of conservation of mass is followed. This means that the total mass of the reactants must equal the total mass of the products.

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What are coefficients in a balanced chemical equation?

They are the numbers placed in front of each chemical formula in a balanced equation. They represent the number of moles of each reactant or product involved in the chemical reaction.

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Balance this equation: CaCO3 + HCl → H2O + CO2 + CaCl2

Adjust the coefficients in front of each chemical formula to ensure the same number of each type of atom on both sides of the equation.

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What are coefficients?

Numbers placed in front of chemical formulas in a balanced equation. They represent the relative number of molecules or moles of each reactant and product involved in the reaction.

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Balancing Equation Example

For example, the balanced equation 2H2 + O2 → 2H2O means two molecules of hydrogen react with one molecule of oxygen to produce two molecules of water.

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Why are subscripts important?

Subscripts within a chemical formula indicate the number of atoms of each element present in a molecule. They are never changed when balancing an equation.

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False Statement about Balancing

The statement "While balancing a chemical equation, all subscripts must be conserved" is false. Only the coefficients are adjusted.

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Balance: Mg + O2 → MgO

The balanced equation is 2Mg(s) + O2(g) → 2MgO(s). This means two magnesium atoms react with one oxygen molecule to produce two molecules of magnesium oxide.

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Balance: BaCl2 + H2SO4 → BaSO4 + HCl

The balanced equation is BaCl2(aq) + H2SO4(aq) → BaSO4(s) + 2HCl(aq). This means one barium chloride molecule reacts with one sulfuric acid molecule to produce one barium sulfate molecule and two hydrochloric acid molecules.

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Balance: Sb + O2 → Sb2O5

The balanced equation is 4Sb(s) + 5O2(g) → 2Sb2O5(s). The coefficient of the underlined substance, antimony (Sb), is 4.

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Balance: C4H10 + O2 → CO2 + H2O

The balanced equation is 2C4H10(g) + 13O2(g) → 8CO2(g) + 10H2O(g). The coefficient of oxygen (O2) is 13.

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Balance: CH3OH + O2 → CO2 + H2O

The balanced equation is 2CH3OH(l) + 3O2(g) → 2CO2(g) + 4H2O(g). The coefficient of oxygen (O2) is 3.

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Chemical Reaction Clues

Changes like color change, formation of a solid, or bubbles forming, indicate a chemical reaction has occurred.

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Coefficients in Equations

Numbers placed in front of chemical formulas to balance the number of atoms of each element in a chemical equation.

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Why Balance Equations?

To ensure the law of conservation of mass is followed in a chemical reaction. The total mass of reactants equals the total mass of products.

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Subscripts vs. Coefficients

Subscripts within a formula indicate the number of atoms of each element in a molecule. Coefficients are placed in front of formulas and are adjusted when balancing equations.

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Coefficient in a Balanced Equation

The number placed in front of a chemical formula in a balanced equation. It represents the relative number of molecules or moles of that substance involved in the reaction.

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Balancing Equation: Step-by-Step

  1. Write the unbalanced equation
  2. Count the number of atoms of each element on both sides of the equation
  3. Adjust the coefficients (numbers in front of chemical formulas) to balance the number of atoms of each element
  4. Check your work by recounting the number of atoms of each element on both sides.
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Why Balance Chemical Equations?

To ensure that the Law of Conservation of Mass is followed in a chemical reaction. This law states that matter cannot be created or destroyed, only transformed.

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Balancing Example: Na + Hâ‚‚O

The balanced equation for the reaction of sodium (Na) with water (H₂O) is 2Na + 2H₂O → 2NaOH + H₂. This means two sodium atoms react with two water molecules to produce two sodium hydroxide molecules and one hydrogen molecule.

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Law of Conservation of Mass

States that in a closed system, the total mass of the reactants before a chemical reaction must be equal to the total mass of the products after the reaction.

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What are Subscripts in Chemical Formulas?

Numbers written below and to the right of an element's symbol in a chemical formula. They represent the number of atoms of that element in a molecule.

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Balancing Equation: Importance

Ensures that the Law of Conservation of Mass is followed in a chemical reaction, meaning the total mass of reactants equals the total mass of products.

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What is the coefficient of O2 in the balanced equation: C2H6 + O2 → CO2 + H2O?

The coefficient of O2 is 7. This means seven molecules of oxygen gas are required to react with two molecules of ethane (C2H6).

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Balance this equation: Li(s) + O2(g) → Li2O(s)

Adjust the coefficients in front of each chemical formula to ensure an equal number of each type of atom on both sides of the equation. The balanced equation is: 4Li(s) + O2(g) → 2Li2O(s)

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Balance this equation: MgCl2 + K3PO4 → Mg3(PO4)2 + KCl

Adjust the coefficients in front of each chemical formula to ensure an equal number of each type of atom on both sides of the equation. The balanced equation is: 3MgCl2 + 2K3PO4 → Mg3(PO4)2 + 6KCl

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What is the coefficient of KCl in the balanced equation: MgCl2 + K3PO4 → Mg3(PO4)2 + KCl?

The coefficient of KCl is 6. This means there will be six molecules of potassium chloride (KCl) produced in the reaction.

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Why is Balancing Important?

It ensures that the law of conservation of mass is followed. The total mass of reactants must equal the total mass of products.

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Subscripts and Balancing

Subscripts within a chemical formula indicate the number of atoms of each element present in a molecule. They are NEVER changed when balancing an equation.

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What do coefficients NOT represent?

Coefficients in a balanced equation do NOT represent the actual number of molecules or moles present in a reaction. They indicate the relative proportion of reactants and products.

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What happens when you change a coefficient?

Changing a coefficient in a balanced equation affects the number of moles of that substance involved, but it also affects the number of moles of all other substances involved.

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What is a balanced chemical equation?

A balanced chemical equation represents a chemical reaction where the number of atoms of each element on the reactant side is equal to the number of atoms of that element on the product side.

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What are coefficients in a balanced equation?

Coefficients are the numbers placed in front of each chemical formula in a balanced equation. They represent the relative number of molecules or moles of each reactant and product involved in the reaction.

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What is the purpose of balancing an equation?

Balancing an equation ensures that the number of atoms of each element on the reactants' side of a chemical reaction is equal to the number of atoms of that element on the products' side. This obeys the law of conservation of mass.

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How to balance chemical equations?

To balance chemical equations, adjust the coefficients in front of each chemical formula. Never change the subscripts within the formulas. Coefficients are whole numbers that represent the number of molecules or moles involved.

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What does a balanced chemical equation look like?

It shows the relative numbers of molecules or moles of each reactant and product involved, ensuring the same number of atoms of each element on both sides.

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What is a coefficient in a balanced equation?

A number placed in front of a chemical formula in a balanced equation, indicating the relative number of molecules or moles of that substance involved in the reaction.

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Balancing Chemical Equations: Step-by-Step

  1. Write the unbalanced equation. 2. Count atoms of each element on both sides. 3. Adjust coefficients to balance atom numbers. 4. Recount atoms to confirm balance.
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Subscripts in Chemical Formulas

Numbers written below and to the right of an element's symbol in a chemical formula. They indicate the number of atoms of that element in a molecule.

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Balancing Chemical Equation (Example)

For example, the balanced equation 2H₂ + O₂ → 2H₂O means two molecules of hydrogen react with one molecule of oxygen to produce two molecules of water.

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What does a balanced equation look like?

It shows the relative numbers of molecules or moles of each reactant and product involved, ensuring the same number of atoms of each element on both sides.

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Coefficients vs. Subscripts

Subscripts within a chemical formula indicate the number of atoms of each element present in a molecule. They are never changed when balancing an equation. Coefficients are placed in front of formulas and are adjusted to balance the equation.

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Coefficients in Balanced Equations

Numbers placed in front of chemical formulas in a balanced equation. They represent the relative number of molecules or moles of each reactant and product involved in the reaction.

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Balancing Chemical Equations: Why?

Ensuring the law of conservation of mass is followed in a chemical reaction. The total mass of reactants must equal the total mass of products.

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Balancing Chemical Equations: How to

Adjust the coefficients in front of each chemical formula. Never change the subscripts within the formulas. Coefficients are whole numbers representing the number of molecules or moles involved.

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Coefficients

The numbers placed in front of chemical formulas in a balanced chemical equation. They represent the relative number of molecules or moles of each reactant and product involved in the reaction.

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Why are Balanced Equations Important?

Balancing chemical equations ensures that the law of conservation of mass is followed - the total mass of the reactants must equal the total mass of the products.

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What Coefficients DON'T Represent

Coefficients in a balanced equation do NOT represent the actual number of molecules or moles present in a reaction. They indicate the relative proportion of reactants and products.

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Purpose of Balancing Equations

Balancing an equation ensures that the number of atoms of each element on the reactants' side of a chemical reaction is equal to the number of atoms of that element on the products' side. This obeys the law of conservation of mass.

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Study Notes

Chemistry Definitions

  • Science: A framework for acquiring and organizing knowledge; a process for understanding information.
  • Chemistry: The science of matter and its transformations.

Scientific Method

  • Scientific Method: The core of scientific inquiry.
  • Natural Law: A statement describing observed behavior (often mathematical).
  • Hypothesis: A suggested explanation for an observation.
  • Theory: A set of tested hypotheses explaining a natural phenomenon.

Steps of the Scientific Method

  • Make an observation.
  • Formulate a hypothesis.
  • Perform an experiment.
  • Develop a theory (or model). (Note: Changing results to match a hypothesis is incorrect)

Laws and Theories

  • Law: A summary of observed behavior; a statement about the world.
  • Theory: An explanation of the behavior.

Quantitative vs. Qualitative Observations

  • Quantitative Observation (Measurement): Includes a number and a unit.
  • Qualitative Observation: Describes qualities without numbers.

Examples

  • Quantitative: "The temperature is 60°C."
  • Qualitative: "The leaf is short."

Key Concepts

  • In a balanced chemical equation, the number of atoms of each element is the same on both sides of the equation.
  • Coefficients are used to balance the number of atoms.
  • Subscripts within a chemical formula are not changed during balancing.
  • Phases (solid, liquid, gas, aqueous) are often shown but are not critical for balancing an equation.
  • Coefficients may include fractional numbers, but simplified integer values are preferred when possible.

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