JEE Advanced levelNumerical answerDifficulty 3 of 3ev055
A building clad in marble is exposed to 3700L of acid rain containing HX2SOX4 at 2.5×10−4molL−1 and HNOX3 at 1.0×10−4molL−1. Assume both acids are fully dissociated (both protons of HX2SOX4) and all the acid reacts with CaCOX3 according to CaCOX3+2HX+CaX2++HX2O+COX2. Using molar mass of CaCOX3 = 100 g/mol, calculate the mass of CaCOX3 dissolved, in grams, to the nearest integer.
Numerical answer type, answer in g, tolerance 0.5.
Answer: 111 g
Total HX+ per litre = 2(2.5×10−4)+1.0×10−4=6.0×10−4 mol. In 3700 L: 3700×6.0×10−4=2.22 mol HX+. Two HX+ react per CaCOX3, so 1.11 mol CaCOX3, mass =1.11×100=111 g.