Chemistry Reaction Stoichiometry Quiz

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Questions and Answers

What is reaction stoichiometry based on? What principle does it follow?

Law of conservation of mass

Why do we use significant figures? How do you know how many to use?

We use measurements. We know how many to use by looking at the number given in the problem.

What can coefficients in a chemical reaction be interpreted as? What are the units you can use to describe them?

Moles or molecules.

What two units does molar mass compare?

Moles to grams or grams to moles. Signup and view all the answers

What is the mole ratio of iron(III) phosphate to sodium phosphate?

2:2 Signup and view all the answers

How many steps does each type of conversion require?

Mass:mole - 2, mole:mass - 2, mole:mole - 1, mass:mass - 3 Signup and view all the answers

What do ideal conditions mean? What does theoretical yield mean?

It is like a perfect world, everything goes exactly as it should. Theoretical yield means every reactant becomes product. Signup and view all the answers

What different conversions are used when doing the different steps of stoichiometry?

Molar mass for step 1, mole ratio for step 2, molar mass for step 3. Signup and view all the answers

Define limiting reactant. Define excess reactant.

The limiting reactant limits how much product can be made. Excess reactants do not have limits and have leftovers. Signup and view all the answers

Which yield gives you an idea of the efficiency of a reaction?

Percentage yield tells you what you actually got on the test. Signup and view all the answers

What do balanced chemical equations tell us?

Mole ratios of the various reactants and products. Signup and view all the answers

How does the actual yield compare to theoretical yield?

Actual yield is less than theoretical yield. Signup and view all the answers

Distinguish between theoretical yield, actual yield, and percentage yield.

Theoretical is maximum yield of any reaction. Actual yield is the experimental yield of any reaction. Percentage yield is a ratio of the two. Signup and view all the answers

How many moles of iron(III) phosphate are required to completely react with 7 moles of sodium sulfate?

5 mol FePO4 Signup and view all the answers

How many moles of iron(III) sulfate are produced if 85.0 g of sodium sulfate is reacted with excess iron(III) phosphate?

0.299 mol Fe2(SO4)3 Signup and view all the answers

How many grams of sodium phosphate are produced if 3.20 mol of iron(III) phosphate are reacted with excess sodium sulfate?

525 g Na3PO4 Signup and view all the answers

How many grams of sodium sulfate are required to react completely with 85g of iron(III) phosphate?

120 g Na2SO4 Signup and view all the answers

Which is the limiting reactant and which is the excess reactant when 5.00 moles of sodium sulfate and 6.00 moles of iron(III) phosphate are allowed to react?

Na2SO4 is limiting. FePO4 is excess. Signup and view all the answers

Calculate the percent yield if the reaction yields 567g of iron(III) sulfate.

85% Fe2(SO4)3 Signup and view all the answers

Write the formula equation and balance: Aqueous strontium chloride reacts with aqueous sodium hydroxide to form solid strontium hydroxide and aqueous sodium chloride.

SrCl2(aq) + 2NaOH(aq) -> Sr(OH)2(s) + 2NaCl(aq) Signup and view all the answers

Stoichiometry is the branch of chemistry that deals with elements in compounds and with reactants and products in chemical reactions focusing on:

Mass relationships Signup and view all the answers

Reaction stoichiometry is based on chemical equations and:

The law of conservation of mass Signup and view all the answers

The number of significant figures in an answer to a stoichiometry problem is determined only by:

The number of significant figures of any measured quantities in the problem Signup and view all the answers

In stoichiometry, molar mass is used to:

Relate the mass of a substance to the amount in moles of that substance Signup and view all the answers

Molar mass can be used to relate:

All of the above Signup and view all the answers

Molar masses are determined from:

The periodic table Signup and view all the answers

The type of stoichiometry problem that involves the most steps is a:

Mass-to-mass conversion Signup and view all the answers

The measured amount of product obtained from a chemical reaction is the:

Actual yield Signup and view all the answers

The efficiency of a chemical reaction is best expressed by the:

Percentage yield Signup and view all the answers

What is the correct mathematical expression for the relationship among percentage yield, actual yield, and theoretical yield?

Percentage yield = actual yield / theoretical yield x 100 Signup and view all the answers

Study Notes

Reaction Stoichiometry

Based on the Law of Conservation of Mass, which states that mass is neither created nor destroyed in a chemical reaction.
Significance of mole ratios is evident in balanced chemical equations, indicating the proportions of reactants and products.

Significant Figures

Significant figures (sig figs) are crucial for accuracy in measurements and calculations.
The number of sig figs used is determined by the given values in the problem.

Chemical Coefficients

Coefficients represent quantities of substances in moles or molecules.
They establish the ratios between reactants and products in a chemical equation.

Molar Mass

Molar mass serves as a conversion factor between moles and grams (and vice versa).
It is determined from the periodic table, essential for stoichiometric calculations.

Mole Ratios

In the chemical reaction 2FePO4 + 3Na2SO4 -> Fe2(SO4)3 + 2Na3PO4, the ratio of iron(III) phosphate to sodium phosphate is 2:2.
Other relevant ratios can be established based on the coefficients from the balanced equation.

Conversion Steps

Different stoichiometric conversions require varying steps:
- Mass to Mole: 2 steps
- Mole to Mass: 2 steps
- Mole to Mole: 1 step
- Mass to Mass: 3 steps

Ideal Conditions & Yields

Ideal conditions refer to a scenario where reactions proceed without any losses.
Theoretical yield is the maximum amount of product formed under perfect conditions.
Actual yield is the amount produced in an experiment, typically less than theoretical yield.
Percentage yield measures the efficiency of a reaction, calculated as:
[ \text{Percentage Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100 ]

Limiting and Excess Reactants

The limiting reactant dictates the maximum yield of the product.
Excess reactants are present in quantities greater than necessary, leading to leftovers.

Yield Calculations

Comparing actual yield to theoretical yield helps understand the efficiency of reactions.
For example, in the reaction involving sodium sulfate and iron(III) phosphate, if 567 g of iron(III) sulfate is produced, the calculated percentage yield is 85%.

Balancing Chemical Equations

To balance a reaction, the correct stoichiometric coefficients must be determined. Example:
- SrCl2(aq) + 2NaOH(aq) -> Sr(OH)2(s) + 2NaCl(aq).

Stoichiometry Fundamentals

Stoichiometry focuses on mass relationships among reactants and products.
Different types of stoichiometric problems include mole-to-mole, mole-to-mass, mass-to-mole, and mass-to-mass conversions.
The most complex problems involve mass-to-mass conversions.

Yield Definitions

Actual yield is the measured quantity of product from a reaction.
Theoretical yield is the calculated maximum product amount that could be formed.
Percentage yield indicates the effectiveness of a reaction and is crucial for evaluating reaction efficiency.

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Description

Test your knowledge on reaction stoichiometry, including concepts like the Law of Conservation of Mass, mole ratios, and molar mass. This quiz covers essential principles and calculations that are foundational to understanding chemical reactions and their proportions.