Q: Which formula is used to calculate the mass percentage of a component in a solution?

$$\text{mass percentage} = \frac{\text{mass of one component}}{\text{mass of whole solution}} \times 100$$

Q: Which of the following is the correct formula for calculating parts per million (ppm)?

$$ppm = \frac{\text{mass of solute}}{\text{mass of solution}} \times 10^6$

Q: Which of the following is the correct formula for volume percentage?

$$\text{volume percentage} = \frac{\text{volume of one component}}{\text{volume of whole solution}} \times 100$$

Q: Which of the following is the correct formula for mass-volume percentage?

$$\text{mass-volume percentage} = \frac{\text{mass of solute}}{\text{solution volume}} \times 100$$

Question 1

Which of the following best describes the concept of a limiting reactant in a chemical reaction?

Accepted Answer

The reactant that determines the maximum amount of product that can be formed.

Question 2

Given the balanced equation: $$2KClO_3 \rightarrow 2KCl + 3O_2$$, how many moles of $$O_2$$ are produced from 4 moles of $$KClO_3$$?

Accepted Answer

$$6$$ moles

Question 3

A student wants to dilute $$52.10 mL of$$ $$0.178 M $$HCl to make a $$0.132 M $$solution. What will be the final volume after dilution?

Accepted Answer

$$70.26 mL$$

Question 4

Which formula is used to calculate the mass percentage of a component in a solution?

Accepted Answer

$$	ext{mass percentage} = \frac{	ext{mass of one component}}{	ext{mass of whole solution}} 	imes 100$$

Question 5

In the reaction $$Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2$$, if you start with $$1.0457$$ mol $$Fe_2O_3$$ and $$3.0631$$ mol $$CO$$, what is the limiting reactant?

Accepted Answer

$$CO$$

Question 6

A solution is prepared by dissolving $$390 mg of $$sodium ion in $$200.0 g of $$water. What is the concentration in ppm?

Accepted Answer

$$1.95 	imes 10^3$ ppm

Question 7

Which of the following equations correctly relates the concentrations and volumes before and after dilution?

Accepted Answer

$$M_1V_1 = M_2V_2$$

Question 8

In the reaction $$3H_2(g) + N_2$(g) \rightarrow 2NH_3(g)$$, how many moles of $$NH_3$$ can be produced from $$6$$ moles of $$H_2$$ and $$2$$ moles of $$N_2$$?

Accepted Answer

$$4$$ moles

Question 9

If the actual yield of a reaction is $$85.8 g $$and the theoretical yield is $$114.0 g$$, what is the percent yield?

Accepted Answer

$$75.3\%$$

Question 10

Which of the following is the correct formula for calculating parts per million (ppm)?

Accepted Answer

$$ppm = \frac{	ext{mass of solute}}{	ext{mass of solution}} 	imes 10^6$

Question 11

In photosynthesis, the balanced equation is $$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2. If$$ $$0.859$$ mol $$CO_2 is $$consumed, how many moles of $$C_6H_{12}O_6$ are produced?

Accepted Answer

$$0.143$$ mol

Question 12

A chemical reaction has a theoretical yield of $$50 g $$but only $$40 g of $$product is actually obtained. What is the percent yield?

Accepted Answer

$$80\%$$

Question 13

Which of the following is NOT a reason why the actual yield of a reaction is often less than the theoretical yield?

Accepted Answer

All reactants are always completely converted to products.

Question 14

If $$3$$ cups of cheese and $$2$$ cups of tomato sauce are needed to make $$1$$ pizza, how many pizzas can be made from $$9$$ cups of cheese and $$8$$ cups of tomato sauce?

Accepted Answer

$$3$$ pizzas

Question 15

Which of the following is the correct formula for volume percentage?

Accepted Answer

$$	ext{volume percentage} = \frac{	ext{volume of one component}}{	ext{volume of whole solution}} 	imes 100$$

Question 16

In the reaction $$N_2 + 3H_2$$ \rightarrow 2NH_3$$, if you have 8.63$ g N_2$ and 2.6$ g H_2$, which is the limiting reactant?

Accepted Answer

$$H_2$$

Question 17

A solution contains $$0.132 M $$HCl after dilution. If you started with $$52.10 mL of$$ $$0.178 M $$HCl, what was the final volume?

Accepted Answer

$$70.26 mL$$

Question 18

If $$6$$ moles of $$CO_2$$ are required to produce $$1$$ mole of $$C_6H_{12}O_6$ in photosynthesis, how many moles of CO_2$ are needed to produce 4$ moles of C_6H$$_{12}$$O_6$$?

Accepted Answer

$$24$$ moles

Question 19

Which of the following is the correct formula for mass-volume percentage?

Accepted Answer

$$	ext{mass-volume percentage} = \frac{	ext{mass of solute}}{	ext{solution volume}} 	imes 100$$

Stoichiometry, Limiting Reactants, Solution Concentrations, and Yield Calculations

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