Question

a 25 ml volume of a sodium hydroxide solution requires 19.6 mL of a 0.189 M HCl acid for neutralization. A 10 mL volume of phosphoric acid solution requires 34.9 mL of the NaOH solution for complete neutralization. Calculate the concentration of the phosphoric acid solution.

Answer 1

Answer: 0.172 M

Step-by-step explanation:

a) To calculate theconcentration 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
`HCl`

`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=1\\M_1=0.189M\\V_1=19.6mL\\n_2=1\\M_2=?\\V_2=25mL`

Putting values in above equation, we get:

`1* 0.189* 19.6=1* M_2* 25\\\\M_2=0.148`

b) 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
`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=?\\V_1=10mL\\n_2=1\\M_2=0.148\\V_2=34.9mL`

Putting values in above equation, we get:

`3* M_1* 10=1* 0.148* 34.9\\\\M_1=0.172M`

The concentration of the phosphoric acid solution is 1.172 M