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Questions and Answers
What occurs when NaOH dissolves in water?
What occurs when NaOH dissolves in water?
Which of the following statements is true regarding the solubility of ionic compounds?
Which of the following statements is true regarding the solubility of ionic compounds?
What type of reaction occurs when an acid neutralizes a base?
What type of reaction occurs when an acid neutralizes a base?
Which situation would most likely result in no reaction when mixing ionic solutions?
Which situation would most likely result in no reaction when mixing ionic solutions?
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What is the correct classification of a reaction that absorbs heat?
What is the correct classification of a reaction that absorbs heat?
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Which of the following ions is always soluble in water?
Which of the following ions is always soluble in water?
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What is the heat of combustion?
What is the heat of combustion?
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Which of the following statements accurately reflects the behavior of precipitation reactions?
Which of the following statements accurately reflects the behavior of precipitation reactions?
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What determines the limiting reactant in a chemical reaction?
What determines the limiting reactant in a chemical reaction?
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How do you calculate the percent composition of an element in a compound?
How do you calculate the percent composition of an element in a compound?
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What happens when reactants are mixed in proportions that do not match the balanced equation?
What happens when reactants are mixed in proportions that do not match the balanced equation?
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If you have 4 moles of NH3 in the reaction 4NH3 + 5O2 --> 6H2O + 4NO, how many grams of H2O are produced?
If you have 4 moles of NH3 in the reaction 4NH3 + 5O2 --> 6H2O + 4NO, how many grams of H2O are produced?
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What is the molecular weight of ethane (C2H6)?
What is the molecular weight of ethane (C2H6)?
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In the reaction 4NH3 + 5O2 --> 6H2O + 4NO, what is the number of moles of O2 required to produce 0.6 moles of H2O?
In the reaction 4NH3 + 5O2 --> 6H2O + 4NO, what is the number of moles of O2 required to produce 0.6 moles of H2O?
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If 15 moles of H2O is produced in the reaction 4NH3 + 5O2 --> 6H2O + 4NO, how many grams of NO are produced?
If 15 moles of H2O is produced in the reaction 4NH3 + 5O2 --> 6H2O + 4NO, how many grams of NO are produced?
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How many moles of H2O can be produced from 3.5 moles of O2 in the reaction 4NH3 + 5O2 --> 6H2O + 4NO?
How many moles of H2O can be produced from 3.5 moles of O2 in the reaction 4NH3 + 5O2 --> 6H2O + 4NO?
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When calculating the moles of a substance, what is the common mistake made in the equation mole = gram + molecular weight?
When calculating the moles of a substance, what is the common mistake made in the equation mole = gram + molecular weight?
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If you were to combine 2.5 moles of NH3 with excess oxygen, how many grams of NO will be produced according to the reaction 4NH3 + 5O2 --> 6H2O + 4NO?
If you were to combine 2.5 moles of NH3 with excess oxygen, how many grams of NO will be produced according to the reaction 4NH3 + 5O2 --> 6H2O + 4NO?
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In a reaction, if the limiting reactant is 2 moles of H2, how will it affect the amount of product formed?
In a reaction, if the limiting reactant is 2 moles of H2, how will it affect the amount of product formed?
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Study Notes
Stoichiometry & Chemical Reactions in Aqueous Solution
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Learning Objectives: Students will be able to:
- Solve stoichiometric problems
- Calculate percent composition
- Understand limiting reactants
- Understand heat of reaction
- Predict if ions react in aqueous solutions
Moles and Molecular Scale
- Moles provide a connection between molecular and macroscopic scales.
- One mole of any substance contains the same number of molecules.
- Avogadro's number (approximately 6.022 x 1023) represents the number of molecules in one mole.
- Mole calculations involve converting between grams, moles, and molecules.
Example Calculation
- Given the reaction 2H2 + O2 → 2H2O:
- 2 molecules of H2 + 1 molecule of O2 produce 2 molecules of H2O.
- 4.0 amu H2 + 32.0 amu O2 produce 36.0 amu H2O
- 2 moles H2 + 1 mole O2 produce 2 moles H2O.
- 4.0 g H2 + 32.0 g O2 produce 36.0 g H2O.
Further Calculations
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Reaction: 4NH3 + 5O2 → 6H2O + 4NO
- If 15 moles of H2O are produced, 10 moles of NO are produced.
- If 2.2 moles of NH3 react, 3.3 moles of H2O are produced (approximately 59.47 g).
Molecular Weight
- Molecular weight is the sum of the atomic weights of all atoms in a molecule.
- For example, the molecular weight of ethane (C2H6) is approximately 30.0 amu.
- (2 * 12.0 amu) + (6 * 1.01 amu)
Determining O2 Needed for Reaction
- For the reaction 4NH3 + 5O2 → 6H2O + 4NO:
- 0.3 moles of H2O require 0.25 moles of O2 (approximately 8g).
Stoichiometric Calculations
- Use balanced chemical equations to determine quantities of reactants and products.
- Using molar masses and stoichiometric ratios, calculate quantities in grams.
- Gram → mole → mole → Gram
Limiting Reactants
- The limiting reactant determines the maximum amount of product possible.
- If the reactants are not mixed in their stoichiometric ratio, one reactant will be consumed completely, limiting the product yield
Identifying Limiting Reactants
- In the reaction HCl + NaOH → H2O + NaCl:
- Using the correct coefficients in the balanced reaction helps determine the limiting reactant and the amount of product formed.
Percent Composition
- The percentage of each element in a compound is determined by comparing the element's mass to the total molecular mass.
- The formula is: (number of atoms × atomic weight)/molecular weight × 100%
- e.g., calculating %C and %H in ethane (C2H6).
Predicting Ion Reactions in Aqueous Solutions
- Many ionic compounds dissolve in water, dissociating into ions.
- Predicting if ions react depends on the formation of insoluble solids (precipitate), gases or neutralisation reactions.
- Reactions like NaOh + H2O = Na+ + OH-
Important Solubility Rules
- Common ionic compounds with Na+, K+, and NH₄+ are soluble in water.
- Most nitrates and acetates are soluble.
- Most chlorides and sulfates are soluble, with exceptions.
- Most carbonates, phosphates, sulfides, and hydroxides are insoluble, with exceptions.
Heat of Reaction
- The heat absorbed or released during a reaction is the heat of reaction.
- Exothermic reactions release heat (e.g., combustion).
- Endothermic reactions absorb heat.
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Description
Test your understanding of stoichiometry and chemical reactions in aqueous solutions. This quiz covers percent composition, limiting reactants, heat of reaction, and the behavior of ions in solutions. Assess your ability to solve stoichiometric problems and apply molecular scale concepts.
