# How to Calculate Percentage by Mass in a Solution

## What does it mean when a solution contains 39% phosphoric acid by mass?

A. 100 g of this solution contains 39 g of phosphoric acid

B. 1 mL of this solution contains 39 g of phosphoric acid

C. 1 L of this solution has a mass of 39 g

D. 1 L of this solution contains 39 mL of phosphoric acid

E. The density of this solution is 3.9 g/mL

## Answer: A. 100 g of this solution contains 39 g of phosphoric acid

When a solution contains 39% phosphoric acid by mass, it means that in 100 grams of the solution, there are 39 grams of phosphoric acid. This percentage by mass formula can be calculated using the equation: (Mass of element / Mass of compound) * 100%.

For example, if you have 100 grams of a solution that contains 39% phosphoric acid by mass, it signifies that 39 grams of the total mass is made up of phosphoric acid. Understanding how to calculate percentage by mass is crucial in chemistry to determine the composition of solutions accurately.

By utilizing this formula and applying it to various solutions, you can determine the proportion of different components within the solution. This knowledge is essential for conducting experiments, formulating solutions, and understanding chemical reactions.

In conclusion, knowing how to calculate percentage by mass in a solution, such as one containing 39% phosphoric acid, is a fundamental skill in chemistry that aids in accurate composition analysis and experimentation.