Question

ou are titrating a solution of sodium hydroxide of unknown concentration with a solution of phosphoric acid that has a concentration of 0.300 M. Starting with 29.0 mL of the sodium hydroxide solution, youuse 16.8 mL of the acid to titrate the base to the endpoint. Calculate the concentration of the sodium hydroxide solution.

Answer 1

Answer : The concentration of the sodium hydroxide solution is, 0.521 M

Explanation :

To calculate the concentration of base, 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 $H_3PO_4$

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

We are given:

$n_1=3\\M_1=0.300M\\V_1=16.8mL\\n_2=1\\M_2=?\\V_2=29.0mL$

Putting values in above equation, we get:

$3\times 0.300M\times 16.8mL=1\times M_2\times 29.0mL\\\\M_2=0.521M$

Thus, the concentration of the sodium hydroxide solution is, 0.521 M