Q: Which equation correctly represents the calculation for mass percent?

$\text{Mass Percent} = \frac{\text{Mass Component}}{\text{Total Mass}} \times 100\%$

Question 1

Which of the following best describes the meaning of 'mass percent' in a chemical solution?

Accepted Answer

The ratio of the mass of solute to the total mass of solution, multiplied by 100.

Question 2

A solution is prepared by dissolving $23.0\ \mathrm{g}$ of NaOH in enough water to make $100\ \mathrm{g}$ of solution. What is the mass percent of NaOH in the solution?

Accepted Answer

$23.0\%$

Question 3

If you have a $230\ \mathrm{g}$ sample of solution that is $23.0\%$ NaOH by mass, how many grams of NaOH are present?

Accepted Answer

$52.9\ \mathrm{g}$

Question 4

A chemist needs to prepare $500\ \mathrm{g}$ of a $10.0\%$ KCl solution by mass. How many grams of KCl are required?

Accepted Answer

$50.0\ \mathrm{g}$

Question 5

A solution is made by dissolving $51.0\ \mathrm{g}$ of KBr in $310\ \mathrm{g}$ of water. What is the mass percent of KBr in the solution? (Round to the nearest tenth.)

Accepted Answer

$14.1\%$

Question 6

A nurse needs to prepare $250\ \mathrm{g}$ of a $5.0\%$ saline solution for a patient. How many grams of NaCl and water are needed?

Accepted Answer

$12.5\ \mathrm{g}$ NaCl, $237.5\ \mathrm{g}$ water

Question 7

Which equation correctly represents the calculation for mass percent?

Accepted Answer

$	ext{Mass Percent} = \frac{	ext{Mass Component}}{	ext{Total Mass}} 	imes 100\%$

Question 8

A laboratory technician needs to make $1.00\ \mathrm{kg}$ of a $15.0\%$ glucose solution by mass. How many grams of glucose and water are required?

Accepted Answer

$150\ \mathrm{g}$ glucose, $850\ \mathrm{g}$ water

Question 9

A solution contains $18.3\%$ urea by mass. If the total mass of the solution is $120.0\ \mathrm{g}$, what is the mass of urea present?

Accepted Answer

$22.0\ \mathrm{g}$

Question 10

A pharmacist needs to dilute a $40.0\%$ (by mass) ethanol solution to make $200\ \mathrm{g}$ of a $20.0\%$ (by mass) ethanol solution. How much water must be added?

Accepted Answer

$50.0\ \mathrm{g}$

Question 11

If a solution is labeled as $10.0\%$ NaCl by mass, which of the following statements is true?

Accepted Answer

There are $10.0\ \mathrm{g}$ of NaCl in every $100\ \mathrm{g}$ of solution.

Question 12

A student prepares a solution by mixing $30.0\ \mathrm{g}$ NaOH with $70.0\ \mathrm{g}$ water. What is the mass percent of NaOH in the solution?

Accepted Answer

$30.0\%$

Question 13

A $500\ \mathrm{g}$ solution contains $75.0\ \mathrm{g}$ of solute. What is the mass percent of solute in the solution?

Accepted Answer

$15.0\%$

Question 14

A solution is $18.3\%$ urea by mass. If you have $97.7\ \mathrm{g}$ of water, what is the total mass of the solution?

Accepted Answer

$120.0\ \mathrm{g}$

Question 15

A $250\ \mathrm{g}$ solution contains $25.0\ \mathrm{g}$ of KNO$_3$. What is the mass percent of KNO$_3$ in the solution?

Accepted Answer

$10.0\%$

Question 16

A solution is prepared by dissolving $20.0\ \mathrm{g}$ of glucose in $180.0\ \mathrm{g}$ of water. What is the mass percent of glucose in the solution?

Accepted Answer

$10.0\%$

Question 17

A $100.0\ \mathrm{g}$ solution contains $23.0\ \mathrm{g}$ NaOH and $77.0\ \mathrm{g}$ water. What is the mass percent of water in the solution?

Accepted Answer

$77.0\%$

Mass Percent in Solutions: Concepts and Calculations

Study Guide - Practice Questions

Study Guide - Flashcards