Question

A sample of pure lithium nitrate contains 10.1% lithium by mass. What is the % lithium by mass in a sample of pure lithium carbonate that has twice the mass of the frost sample?

Answer 1

The % lithium by mass in a sample of pure lithium carbonate : 18.79%

Further explanation

Proust states the Comparative Law that compounds are formed from elements with the same Mass Comparison so that compounds have a fixed composition of elements

% Lithium (Li) in Li₂CO₃(lithium carbonate) will remain the same even if the mass amount of Li₂CO₃ changes

Ar of Li = 6.941 g/mol

MW of Li₂CO₃ = 73.891 g/mol

`\tt \%Li=(2.Ar~Li)/(MW~Li_2CO_3)* 100\%\\\\\5Li=(2* 6.941)/(73.891) * 100\%=18.79\%`