Question

When the following equation is balanced, the coefficient of HNO 3 is __________. HNO 3 (aq) + CaCO 3 (s) → Ca(NO 3) 2 (aq) + CO 2 (g) + H 2O (l)

A.1

B.5

C.2

D.4

E.3

Answer 1

HNO3 + CaCO3 -----------------------> Ca(NO3)2 + CO2 + H2O

on the reactant side H = 1 , Ca = 1 , N = 1 , C = 1 , O = 6

on the product side H = 2 , Ca = 1 , N = 2 , C = 1 , O = 9

so by using the simple coefficients balance the equation as follows

the coefficient 2 is placed in front of HNO3 the it is as follows

2 HNO3 + CaCO3 -----------------------> Ca(NO3)2 + CO2 + H2O

on the reactant side H = 2 , Ca = 1 , N = 2 , C = 1 , O = 9

on the product side H = 2 , Ca = 1 , N = 2 , C = 1 , O = 9 i.e equation is balanced

answer => C.2