Question

A sample of pure lithium carbonate contains 18.8% 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?

Answer 1

There is 18.8% lithium by mass in second sample

Explanation:

Both the two samples are pure lithium carbonate. So % lithium by mass will be same in both samples. This can be proved mathematically as follows-

Let's assume weight of first sample is x g

So, 100 g of sample contains 18.8 g of lithium

Hence, x g of sample contains
`((18.8)/(100)* x)` g of lithium

Now, the second sample has weight equal to 2x g

So, 2x g of sample contains
`((18.8)/(100)* 2x)` g of lithium

So, % lithium by mass in second sample =
`(((18.8)/(100)* 2x)/(2x))* 100` % = 18.8%