7.5 g of an acid are dissolved per litre of the solution. 20 mL of this acid solution required 25 mL of N//15 NaOH solution for complete neutralisation. Calculate the equivalent mass of the acid.

7.5 g of an acid are dissolved per litre of the solution. 20 mL of thi

1.	7.5 g of an acid are dissolved per litre of the solution. 20 mL of this acid solution required 25 mL of N//15 NaOH solution for complete neutralisation. Calculate the equivalent mass of the acid.
Answer» Solution :Calculation of the normality of the acid Volume of acid taken = 20 ML volume of base required = 25 mL Normality of base `= N//15` Applying normality equation : `ubrace(N_(1)xxV_(1))_("Acid") equiv ubrace(N_(2) XX V_(2))_("Base")` `N_(1) xx (20 mL) = ((1)/(15) N) xx 25 mL` `N_(1) = ((1)/(15) N) xx ((25 mL))/((20 mL)) = (1)/(12) N` Step II. Calculation of the equivalent mass of the acid Amount of acid dissolved per litre of solution = 7.5 g `:.` Strength of the acid `= 7.5 g L^(-1)` Equivalent mass of the acid `= ("Strength of the acid")/("Normality of acid") = ((7.5 g L^(-1)))/((1//12 N)) = 90.0`