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

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