4.215 g a metallic carbonate was heated in a hard glass tube and `CO_2` evolved was found to measure 1336 mL at 27°C and 700 mm pressure. What is the equivalent mass of the metal ?

Answer

(12. 15)

Explanation

Moles of `CO_(2)` can be calculated using ideal gas equation as :
`n = (pV)/(RT) = ((700)/(760)) ((1336)/(1000)) xx (1)/(0.082 xx 300) = 0.05`
Also, the decomposition reaction is: `underset(0.05 mol)(MCO_(3)) rarr underset(0.05 mol) (MO + CO_(2))`
`:'` 0.05 mole `MCO_(3) = 4.215g :.` 1.0 mole `M CO_(3) = (4.215)/(0.05) = 84.3` g(molar mass)
`rArr 84.3 = MW " of" M + 12 + 48 rArr` Molecular weight of metal = 24.3
`:.` Metal is bivalent, equivalent weight `= ("Molecular weight")/(2) = 12.15`