Question 1

A student adds 2.4 g of magnesium (atomic mass = 24) to 100 mL of 1 M HCl. Calculate the number of moles of HCl present in the solution before the reaction starts.

Accepted Answer

$0.1$ mol

Question 2

In the reaction $\mathrm{Mg} + 2\mathrm{HCl} \rightarrow \mathrm{MgCl}_2 + \mathrm{H}_2$, what is the limiting reagent when 2.4 g of Mg is added to 100 mL of 1 M HCl?

Accepted Answer

Hydrochloric acid

Question 3

If 2.4 g of Mg reacts with 100 mL of 1 M HCl, how many liters of hydrogen gas ($\mathrm{H}_2$) are produced at STP?

Accepted Answer

$0.56$ L

Question 4

After the reaction between 2.4 g Mg and 100 mL of 1 M HCl is complete, how many moles of magnesium remain unreacted?

Accepted Answer

$0.01$ mol

Question 5

Given 800 g of solution contains 320 g of solute X, what is the mass of solvent in the solution?

Accepted Answer

$480$ g

Question 6

If after cooling, 100 g of solute X is removed from the solution, how much solute X remains?

Accepted Answer

$220$ g

Question 7

What is the total weight of the solution after cooling, given that the solvent is $480$ g and the remaining solute X is $220$ g?

Accepted Answer

$700$ g

Question 8

In the reaction $3\mathrm{Cu} + 8\mathrm{HNO}_3 \rightarrow 3\mathrm{Cu(NO}_3)_2 + 2\mathrm{NO} + 4\mathrm{H}_2\mathrm{O}$, if the molecular weight of $\mathrm{HNO}_3$ is $M$, what is its equivalent weight?

Accepted Answer

$\frac{4}{3}M$

Question 9

A chemist wants to prepare a solution with a solute to solvent mass ratio of $\frac{2}{3}$. If the solvent mass is $480$ g, what should be the mass of solute X?

Question 10

If $0.1$ mol of HCl is available and reacts with excess Mg, how many moles of $\mathrm{H}_2$ gas will be produced?

Accepted Answer

$0.05$ mol

Question 11

Which of the following statements is INCORRECT regarding the reaction of 2.4 g Mg with 100 mL of 1 M HCl?

Accepted Answer

1.12 L of hydrogen is produced at STP

Question 12

In the reaction $3\mathrm{Cu} + 8\mathrm{HNO}_3 \rightarrow 3\mathrm{Cu(NO}_3)_2 + 2\mathrm{NO} + 4\mathrm{H}_2\mathrm{O}$, how many moles of $\mathrm{HNO}_3$ are required to react completely with $3$ moles of Cu?

Accepted Answer

$8$ moles

Question 13

A solution contains $320$ g of solute X in $800$ g of solution. What is the mass percent of X in the solution?

Accepted Answer

$40\%$

Question 14

If $0.01$ mol of Mg is left unreacted after the reaction with HCl, what is the mass of Mg remaining?

Accepted Answer

$0.24$ g

Question 15

Which of the following best explains why HCl is the limiting reagent in the reaction between 2.4 g Mg and 100 mL of 1 M HCl?

Accepted Answer

There are fewer moles of HCl than required to react with all the Mg

Question 16

If the molecular weight of $\mathrm{HNO}_3$ is $M$, what is the formula for its equivalent weight in the reaction $3\mathrm{Cu} + 8\mathrm{HNO}_3 \rightarrow 3\mathrm{Cu(NO}_3)_2 + 2\mathrm{NO} + 4\mathrm{H}_2\mathrm{O}$?

Accepted Answer

$\frac{4}{3}M$

Question 17

A solution initially contains $320$ g of solute X and $480$ g of solvent. After cooling, $100$ g of X precipitates out. What is the new concentration of X in the solution (in g per 700 g solution)?

Accepted Answer

$220$ g / $700$ g$

Question 18

In a chemical reaction, the equivalent weight of an acid is defined as:

Accepted Answer

The mass of acid that supplies or reacts with one mole of hydrogen ions

Question 19

If $3$ moles of Cu react with $8$ moles of $\mathrm{HNO}_3$, how many moles of $\mathrm{NO}$ are produced?

Accepted Answer

$2$ moles

Question 20

A solution contains $320$ g of solute X in $800$ g of solution. If $100$ g of X is removed, what is the percentage decrease in the mass of X?

Accepted Answer

$31.25\%$

Fundamental Concepts in Chemistry: Stoichiometry and Solution Calculations

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