Stoichiometry Chalk Lab

Consider the chemical equation.

2NBr₃ + 3NaOH N₂ + 3NaBr + 3HOBr

If there are 40 mol of NBr₃ and 48 mol of NaOH, what is the excess reactant?

• N₂

• NBr₃

• NaOH

• HOBr

The equation shows the reaction between zinc metal and hydrochloric acid.

Zn(s) + 2HCl(aq) ZnCl₂(aq) + H₂(g)

What is the theoretical yield of hydrogen gas if 5.00 mol of zinc are added to an excess of hydrochloric acid?

• 5.05 g

• 10.1 g

• 182 g

• 682 g

Consider the chemical equation.

2H₂ + O₂ 2H₂O

What is the percent yield of H₂O if 87.0 g of H₂O is produced by combining 95.0 g of O₂ and 11.0 g of H₂?

• 56.5%

• 59.0%

• 88.5%

• 99.7%

Tags

NGSS.HS-PS1-7

Which statement correctly describes the actual yield and the theoretical yield of a reaction?

• The actual yield is calculated from the reactant amounts, but the theoretical yield must be measured for each instance of a reaction.

• The actual yield is calculated from the amount of the limiting reactant, and the theoretical yield is calculated from the amount of the excess reactant.

• The actual yield depends on the reaction conditions, but the theoretical yield varies only with reactant amounts.

• The actual yield represents the maximum yield possible, and the theoretical yield assumes perfect reaction conditions.

Tags

NGSS.HS-PS1-7

Which statement can best be concluded from the ideal gas law?

• The product of pressure and volume of an ideal gas is proportional to the absolute temperature.

• All collisions between atoms or molecules are perfectly elastic and are not the result of any attractive forces.

• The temperature, pressure, and volume of a gas are all related.

• The behavior of a gas under real conditions does not obey the ideal gas law.

Tags

NGSS.HS-PS3-2

If the pressure, volume, and temperature of a gas are known, which can most likely be found by using the ideal gas law?

• the molar amount of the gas

• the partial pressure of the gas

• the standard temperature and pressure

• the molar mass

If a gas is moved from a large container to a small container but its temperature and number of moles remain the same, what would happen to the pressure of the gas?

• It would increase.

• It would be halved.

• It would stay the same.

• It would slightly decrease.

Which describes the volume of 1 mol of gas at standard temperature and pressure?

• The volume is greater for a larger mass of gas.

• The volume is the same for any gas.

• The volume depends on the size of the container.

• The volume varies with the pressure.

A sample of sodium hydroxide (NaOH) has a mass of 160.0 g. The molar mass of NaOH is 40.00 g/mol. How many moles of NaOH does this sample contain?

• 4.000

• 40.00

• 160.0

• 6400

Tags

NGSS.HS-PS1-7

The chemical equation below shows the combustion of propane (C₃H₈).

C₃H₈ + 5O₂ 3CO₂ + 4H₂O

The molar mass of oxygen gas (O₂) is 32.00 g/mol. The molar mass of C₃H₈ is 44.1 g/mol. What mass of O₂, in grams, is required to completely react with 0.025 g C₃H₈?

• 0.018

• 0.034

• 0.045

• 0.091

Tags

NGSS.HS-PS1-7