Question

The density of a solution of 3.69g KBr in 21.70g H2O is 1.11g/mL. What is the %w/v of KBr in the solution?

Answer 1

What volume is 21.70g?
volume = mass/density
Then (3.69/mL volume) x 100

Answer 2

Mass of solution
= 3.69g + 21.70g
=25.39 g

Volume of solution
= 25.39g / 1.11g/mL
=22.9 mL
= 0.0229 L

Moles KCl
= 3.69 g / 74.5513g/mol
= 0.0494961 mol

Molarity of KCl
= 0.0494961 mol / 0.0229L
= 2.1614 mol/L

Answer 3

Now just do that for KBr instead of KCl i.e change the molecular weight in step 3