How many mLs of a 1 M Lithium Chloride solution needs to be added to make a 3% Lithium Chloride solution?

Question

I need to make a 3%, 1%, and 0.3% Lithium Chloride solution in 1 liter of water. There will be a 1 M Lithium Chloride stock solution. How many mL of the stock solution need to be added to make the different concentrations?

Answer 1

Take a look at the stock 1 M solution of LiCl, and see what percent it is.

molar mass LiCl = 42.4 g/mole. So, a 1 M solution has 42.2 g/liter. Since we speak of % solutions as g/100 ml, this is a 4.24% LiCl solution (m/v)

If you want to use this to make 1 L of a 3% solution:

(x ml)(4.24%) = (1000 ml)(3%)

x = 707.5 mls diluted to 1 liter

If you want to use the original stock to make the other dilutions, calculate them the same way.

(x ml)(4.24%) = (1000 ml)(1 %)

x = 23.6 ml

etc. etc.