Stoichiometry and Gas Laws Quiz

A reaction produces 3.50 L of oxygen gas at STP. A student calculates the mass of the reactants using stoichiometry but finds a discrepancy between the theoretical and actual masses. Which of the following could best explain the discrepancy?

• The temperature was not recorded properly.

• The molar volume of the gas was not used correctly.

• The gas volume was not measured at the correct pressure.

• The student did not consider the excess reactant in their calculations.

A reaction between sodium (Na) and chlorine (CI) produces sodium chloride (NaCl). After performing the stoichiometric calculations, the mass of sodium used was higher than expected. What is the best way to evaluate whether the reaction went to completion?

• Check the volume of chlorine gas left over.

• Test the purity of the sodium chloride product.

• Recalculate using the limiting reactant approach.

• Compare the theoretical yield of NaCl with the actual yield.

During the combustion of a hydrocarbon, a student notices that the volume of CO₂ produced is less than predicted by stoichiometry. How should the student evaluate the possible sources of error in the experiment?

• The gas collection system may have leaks.

• The temperature of the experiment fluctuated.

• The reactants were not fully consumed in the reaction.

• All of the above could be potential errors.

A gas collected in a laboratory is found to have a mass lower than the theoretical mass calculated. How should a student evaluate whether an ideal gas assumption was valid in this scenario?

• Conduct the experiment again under different conditions.

• Consider the reaction as incomplete and calculate again.

• Compare the experimental conditions to the assumptions of ideal gas behavior.

• Assume ideal gas behavior does not apply and adjust the stoichiometric calculations accordingly.

A laboratory is conducting an experiment involving the decomposition of sodium azide (NaN) to produce nitrogen gas (N₂) in a car airbag system. If 65.0 g of sodium azide decomposes at STP, how many liters of nitrogen gas will be produced?

• 30.0 L

• 32.8 L

• 35.5 L

• 40.0 L

A student is asked to determine the volume of carbon dioxide gas (CO₂) formed from the combustion of 8.00 g of methane (CH₂) at 1 atm and 273 K. What volume of CO₂ is produced at these conditions?

• 11.2 L

• 16.4 L

• 22.4 L

• 32.0 L

A chemist is reacting propane (C3H) with excess oxygen to produce water and carbon dioxide. How many moles of oxygen are required to react completely with 44.1 grams of propane at STP?

• 3.00 moles

• 5.00 moles

• 6.00 moles

• 10.00 moles

In an industrial process, sulfur dioxide (SO₂) is being produced from the combustion of sulfur (S) in excess oxygen gas. Calculate the volume of SO₂ produced when 16 g of sulfur is burned at STP.

• 5.6 L

• 11.2 L

• 16.8 L

• 22.4 L

A student wants to calculate the mass of water vapor produced from 4.5 L of hydrogen gas reacting with excess oxygen gas at 1 atm and 298 K. What is the mass of water vapor formed?

• 3.6 g

• 4.5 g

• 8.1 g

• 9.0 g