Question

Q.5. In order to find the strength of a sample of sulphuric acid , 10 g of it were taken and a piece of marble weigng 7g placed in it. When the reaction is ceased,the marble piece was dried and it was found to weigh 2.2 g. What is percent strength of sulphuric acid?

Answer 1

Marble is calcium carbonate; the balanced chemical equation is: 


CaCO3 + H2SO4 = CaSO4 + CO2 + H2O



Molar mass of CaCO3 = 100g/mol

Molar mass of H2SO4 = 98g/mol


Mass of marble reacted = 7 - 2.2 = 4.8g


100g Marble reacts with 98g H2SO4

∴4.8g will react with    = (4.8x98)/100

                                   = 4.704


This is the mass of H2SO4 in the 10g


Percent strength of H2SO4 = 4.704/10 * 100


                                            = 47.04%

Answer 2

The strength of Sulphuric acid in sample is 47.04 %