Q: Which calculation would you use to determine the mass of solute needed to make a specific mass percent solution?

$$\text{mass of solute} = \frac{\text{mass percent} \times \text{mass of solution}}{100}$$

Question 1

A solution is prepared by dissolving 8.2 g of glucose (molar mass = 180 g/mol) in enough water to make 620.0 g of solution. What is the mass percent of glucose in the solution? Use the formula:

$$	ext{Mass percent} = \frac{	ext{mass of solute}}{	ext{mass of solution}} 	imes 100$$

Accepted Answer

1.32\%

Question 2

If you have 5.0 g of NaCl dissolved in 95.0 g of water, what is the mass percent of NaCl in the solution?

$$	ext{Mass percent} = \frac{	ext{mass of solute}}{	ext{mass of solution}} 	imes 100$$

Accepted Answer

4.76\%

Question 3

A biochemist needs to prepare 100 g of a 10\% (w/w) glucose solution. How many grams of glucose and water are required?

Accepted Answer

10 g glucose, 90 g water

Question 4

Which of the following best describes the term 'mass percent' in the context of biochemistry solutions?

Accepted Answer

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

Question 5

A student prepares a solution by dissolving 15 g of urea in 135 g of water. What is the mass percent of urea in the solution?

Accepted Answer

10.0\%

Question 6

If a solution contains 22.0 g of KCl in 200.0 g of solution, what is the mass percent of KCl?

Accepted Answer

11.0\%

Question 7

A researcher needs to make 250 g of a 4\% (w/w) NaCl solution. How much NaCl should be weighed out?

Accepted Answer

10 g

Question 8

Which calculation would you use to determine the mass of solute needed to make a specific mass percent solution?

Accepted Answer

$$	ext{mass of solute} = \frac{	ext{mass percent} 	imes 	ext{mass of solution}}{100}$$

Question 9

A solution is labeled as 5\% (w/w) glucose. What does this mean in practical terms?

Accepted Answer

There are 5 g of glucose in every 100 g of solution

Question 10

A scientist accidentally adds 20 g of solute to 80 g of solvent. What is the mass percent of solute in the resulting solution?

Accepted Answer

20\%

Question 11

If you want to dilute a 20\% (w/w) NaCl solution to make 100 g of a 5\% (w/w) NaCl solution, how much of the original solution should you use?

Accepted Answer

25 g

Question 12

Which of the following statements is TRUE regarding the calculation of mass percent?

Accepted Answer

The mass percent will always be less than 100\% for a solute in a solution

Question 13

A solution contains 12 g of sucrose in 88 g of water. What is the mass percent of sucrose?

Accepted Answer

12\%

Question 14

A hospital IV bag contains 0.9\% (w/w) NaCl. If the bag contains 500 g of solution, how many grams of NaCl are present?

Accepted Answer

4.5 g

Question 15

Which of the following is NOT a correct step in calculating the mass percent of a solute in a solution?

Accepted Answer

Dividing the mass of solute by the mass of solvent

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