Hydrochloric acid is purchased in 12 molar concentrations. If I needed 200 ml of 2.0 molar HCl, how many milliliters of the concentrated solution would I need

The answer to your question is 33.3 ml

Explanation:

Data

Stock solution 12M

Volume 2 = 200 ml

Concentration 2 = 2 M

Volume stock = ?

Process

1. - Use the formula for dilutions

C1V1 = C2 V2

- Solve for V1

V1 = C2V2 / C1

2. - Substitution

V1 = (2) (200) / 12

- Simplification

V1 = 400 / 12

3. - Result

V1 = 33.3 ml

4. - Conclusion

We need 33.3 ml of the concentrated solution.