Bunuel wrote:

A chemist mixes a 12-ounce solution that is 45% acid with 8 ounces of solution that is 70% acid. What percent of acid is in the mixture?

A. 11

B. 20

C. 37.5

D. 55

E. 57.5

Method 1:

Amount of acid = 12*45/100 + 8*70/100 = 11 ounces. Total volume = 20 ounces.

% of acid = 11*100/20 = 55 %.

Method 2:

Apply alligation method.

Let percent of acid in the mixture is x.

Please refer the attached diagram.

We have following relation:

\(\frac{70 - x}{x - 45} = \frac{12}{8} \Rightarrow 5x = 275 \Rightarrow x = 55\)

% of acid = 55%

Thanks.

Attachments

Mixtures_Acid.jpeg [ 4.46 KiB | Viewed 1300 times ]