A sample of pure lithium chloride contains 16% lithium by mass.What is the % lithium by mass in a sample of pure lithium carbonate that has twice the mass of the first sample?
A)8.20%
B)16.4%
C)32.8%
D)65.6%

Question

Quizplus · Accepted Answer

In the first sample, if the total mass is 100 g, then the mass of lithium is 16 g. Therefore, the mass of chloride is 84 g.

In the second sample, if the mass of lithium chloride is 2x g, then the mass of lithium in it is 0.16 x 2x = 0.32x g.

Now we need to find what % is 0.32x g of the total mass of lithium carbonate which is twice the mass of lithium chloride, i.e. 2 x 100 = 200 g.

Let the mass of lithium carbonate be 200 g. Then, the mass of lithium in it is 0.16 x 200 = 32 g.

Therefore, % lithium by mass in lithium carbonate sample = (32/200) x 100 = 16%.

So the answer is B, 16.4%.

A Sample of Pure Lithium Chloride Contains 16% Lithium by Mass.What