Question

purse What is the molarity of a NaOH solution, if 100 mL of 0.50 M H2SO4 solution is required to neutralize a 25.0-ml sample of the NaOH solution?

Answer 1

GIVEN THE MOLARITY OF SULPHURIC ACID = 0.5 M AND VOLUME REQUIRED =100mL

Volume of NaOH REQUIRED TO NEUTRALISE THE ACID SOLUTION= 25mL

SINCE H2SO4 IS A DIPROTIC ACID SO IT PROVIDES WITH 2 H+ IONS  

THE REACTION TAKING PLACE IN THE FLASK IS

2NAOH + H2S04 -------> Na2SO4 + 2H20

ALSO N=M * NF(n FACTOR) HERE N FACTOR IS NUMBER OF RELEASABLE HYDROGEN IONS FOR ACID.

Using the formula N1V1=N2V2

N1(NORMALITY FOR H2SO4)= 0.5M * 2 = 1 M

V1=100 mL

V2 (VOL OF NAOH SOLUTION) = 25 mL

PUTTING VALUES IN FORMULA

1 * 100mL=N2 * 25 mL

N2= 4N

HENCE NORMALITY FOR NAOH IS 4 NORMAL

SINCE N FACTOR FOR NAOH IS 1 SO N = M * N FACTOR

SO MOLARITY = NORMALITY = 4M

THUS MOLARITY OF NAOH SOLUTION IS 4 M