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Questions and Answers
Stoichiometry is derived from Greek words. Stoicheion means what?
Stoichiometry is derived from Greek words. Stoicheion means what?
- Measure
- Molecule
- Atom
- Element (correct)
A balanced chemical equation shows that the mass of the reactants is always equal to the mass of the products.
A balanced chemical equation shows that the mass of the reactants is always equal to the mass of the products.
True (A)
In the balanced chemical equation $N_2 + 3H_2 \rightarrow 2NH_3$, what is the mole ratio of $H_2$ to $NH_3$?
In the balanced chemical equation $N_2 + 3H_2 \rightarrow 2NH_3$, what is the mole ratio of $H_2$ to $NH_3$?
3:2
In stoichiometry, the coefficients in a balanced equation represent the smallest whole number _______ between reactants and products.
In stoichiometry, the coefficients in a balanced equation represent the smallest whole number _______ between reactants and products.
For the reaction $2K + 2H_2O \rightarrow 2KOH + H_2$, if you have 4 moles of K, how many moles of $H_2$ will be produced?
For the reaction $2K + 2H_2O \rightarrow 2KOH + H_2$, if you have 4 moles of K, how many moles of $H_2$ will be produced?
To convert from grams to moles, you need to use the mole ratio.
To convert from grams to moles, you need to use the mole ratio.
What three steps are needed for mass-mass calculations?
What three steps are needed for mass-mass calculations?
The only time the number of moles is different than one is when you are using the _______.
The only time the number of moles is different than one is when you are using the _______.
For the reaction $2Al + 6HCl \rightarrow 2AlCl_3 + 3H_2$, if you have 0.2 moles of Al, how many moles of $H_2$ will be produced?
For the reaction $2Al + 6HCl \rightarrow 2AlCl_3 + 3H_2$, if you have 0.2 moles of Al, how many moles of $H_2$ will be produced?
The coefficients in a balanced chemical equation represent the largest whole number ratio between reactants and products.
The coefficients in a balanced chemical equation represent the largest whole number ratio between reactants and products.
In the reaction $2Li(ClO_3) \rightarrow 2LiCl + 3O_2$, what is the mole ratio of $Li(ClO_3)$ to $O_2$?
In the reaction $2Li(ClO_3) \rightarrow 2LiCl + 3O_2$, what is the mole ratio of $Li(ClO_3)$ to $O_2$?
In mass-mass calculations, after converting grams of a known substance to moles, the next step is to convert moles of known to moles of ________.
In mass-mass calculations, after converting grams of a known substance to moles, the next step is to convert moles of known to moles of ________.
For the reaction $3AgCl + Al \rightarrow 3Ag + AlCl_3$, if you start with 54 grams of Al, what is the FIRST step in finding the mass of $Ag$ produced?
For the reaction $3AgCl + Al \rightarrow 3Ag + AlCl_3$, if you start with 54 grams of Al, what is the FIRST step in finding the mass of $Ag$ produced?
Stoichiometry is the measure of atoms.
Stoichiometry is the measure of atoms.
Match the balanced equation interpretation to its type:
Match the balanced equation interpretation to its type:
Flashcards
Stoichiometry
Stoichiometry
The study of the quantitative relationships or ratios between two or more substances undergoing a physical change or chemical reaction.
Mole Ratio
Mole Ratio
The relative number of moles of reactants and products required for a reaction to occur.
Mass-Mass Calculations
Mass-Mass Calculations
The steps to solve this calculation are: convert grams to moles, convert moles of known to moles of unknown, finally convert moles of unknown to grams.
Molecular Interpretation
Molecular Interpretation
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Mass Conservation
Mass Conservation
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Mole Interpretation
Mole Interpretation
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Mole-Mole Calculations
Mole-Mole Calculations
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Study Notes
Stoichiometry: Mole Ratios and Calculations
- Stoichiometry involves using mole ratios in mole-mole and mass-mass calculations.
- It's derived from the Greek words "stoicheion," meaning "element," and "metron," meaning "measure."
- Stoichiometry is defined as the measurement of elements.
Learning Objectives
- Determine the number of moles of a substance produced or consumed using the mole ratio.
- Describe interpretations of balanced equations.
- Review balancing equations.
- Determine an amount of a substance involved in a chemical reaction.
Interpreting Balanced Chemical Equations
- Balanced chemical equations can be interpreted in terms of molecules, mass, and moles.
- An example reaction is:
1N2(g) + 3H2(g) -> 2NH3(g) - In terms of mass, 28.02g of N2 reacts with 6.06g of H2 to produce 34.08g of NH3; the mass of reactants equals the mass of products.
- In terms of moles, 1 mol N2 reacts with 3 mol H2 to produce 2 mol NH3.
Mole-Mole Calculations
- Coefficients in balanced equations represent the smallest whole number mole ratio between reactants and products.
- Example mole ratios for the
1N2(g) + 3H2(g) -> 2NH3(g)reaction include:(1 mol N2 / 2 mol NH3)and(3 mol H2 / 1 mol N2)and(2 mol NH3 / 3 mol H2)
Example 1
- If 3.86 moles of potassium (K) reacts with water, the balanced equation is
2K + 2H(OH) -> 2K(OH) + H2 - To find the moles of hydrogen produced:
(3.86 mol K / 1) * (1 mol H2 / 2 mol K) = 1.93 mol H2
Example 2
- To determine how many moles of aluminum will react with 0.512 moles of hydrochloric acid (HCl), use the balanced equation:
2 Al + 6 HCl -> 2 AlCl3 + 3 H2 - Calculation:
(0.512 mol HCl / 1) * (2 mol Al / 6 mol HCl) = 0.171 mol Al
Mass-Mass Calculations
- Convert grams to moles using the molar mass of the known value.
- Convert moles of known to moles of unknown using the mole ratio.
- Convert moles of unknown to grams using the molar mass of the unknown
Example 1
- To calculate the mass of silver chloride (AgCl) that reacts with 15.0 grams of aluminum (Al), use the balanced equation:
3 AgCl + Al -> 3 Ag + AlCl3 - Calculation:
(15.0 g Al / 1) * (1 mol Al / 26.98 g Al) * (3 mol AgCl / 1 mol Al) * (143.32 g AgCl / 1 mol AgCl) = 239 g AgCl
Example 2
- To calculate the mass of oxygen gas (O2) produced in the decomposition of 37.2 g of lithium chlorate (Li(ClO3)), use the balanced equation:
2 Li(ClO3) -> 2 LiCl + 3 O2 - Calculation:
(37.2 g Li(ClO3) / 1) * (1 mol Li(ClO3) / 90.39 g Li(ClO3)) * (3 mol O2 / 2 mol Li(ClO3)) * (32 g O2 / 1 mol O2) = 19.8 g O2
Important Points
- Mass-mass calculations involve calculating the mass for two different substances.
- Molar mass always equals one mole.
- The number of moles is different than one only when using the mole ratio.
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