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200cm3 of 0.50mol/dm3 solution of calcium hydrogen...

200cm3 of 0.50mol/dm3 solution of calcium hydrogen trioxocarbonate (IV) is heated. The maximum weight of solid precipitated is

A.

10g

B.

25g

C.

20g

D.

15g

Correct answer is A

Equation: Ca(HCO3)2 CaCO3 (precipitate) + H2O + CO2 (in the presence of heat)

V = 200 cm3 = 0.2 dm3

C = 0.5 mol/dm3 = 0.5M

N = CV N = 0.5 × 0.2

= 0.1 mole

From the equation 1 mole of Ca(HCO3)2 gives 100g of CaCO3

(1 mole CaCO3 = 40 + 12 + (3 x 16) = 100g\)

0.1 mole of Ca(HCO3)2 gives x g of CaCO3.

10.10=100x

x=100×0.10=10g