# Help Zone

### Student Question

Secondary III â€¢ 1yr.

Hello! In my homework I need to find the molar concentration of 0.874 kg of H3PO4 in 3L of water, how do I find it?

Science

## Explanations (1)

• Explanation from Alloprof

Explanation from Alloprof

This Explanation was submitted by a member of the Alloprof team.

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Team Alloprof â€¢ 1yr. edited September 2021

Hello!

Thank you for your question ðŸ˜Š

First, remember that the molar concentration (C) of a solution is the number of moles (n) of a substance contained in a certain volume (V). This relationship is illustrated by the following formula:

$$C = \frac{n}{V}$$

In your case, you do not have direct access to the number of moles (n) of H3PO4. However, remember that this variable is equal to the mass of the substance (m) divided by its molar mass (M). This relationship is illustrated by the following formula:

$$n = \frac{m}{M}$$

Since you know the substance, it is then possible to calculate the molar mass by adding the molar masses of these components.

With these formulas, I believe you will be able to find the molar concentration!