Question

A 60.00-mL sample of a weak acid is titrated with 0.0361 M NaOH. At the endpoint, it is found that 38.23 mL of titrant was used. What was the concentration of the weak acid?

Answer 1

Answer: The concentration of weak acid is 0.0230 M

Explanation:

To calculate the concentration of acid, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is weak acid

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is NaOH.

We are given:

$n_1=2\\M_1=?M\\V_1=60.00mL\\n_2=1\\M_2=0.0361M\\V_2=38.23mL$

Putting values in above equation, we get:

$1\times M_1\times 60.00=1\times 0.0361\times 38.23\\\\M_1=\frac{1\times 0.0361\times 38.23}{1\times 60.00}=0.0230M$

Hence, the concentration of weak acid is 0.0230 M