What is the molarity?

Question

What is the molarity of a 0.847m solution of KBr that has a density of 1.18g/mL? If you could explain how you solved it that would be great!

Answer 1

if you have a   0.847molal solution of KBr, you have ...

0.847 moles of KBr mixed with 1000 grams of water

so let's find out how massive the 0.847 moles of KBr is  using its molar mass of 119.01 g/mol:

0.847 moles @ 119.01 g/mol = 100.8 grams of KBr

so let's find out how massive the 0.847 moles of KBr mixed with 1000 grams of water is:

100.8 grams KBr + 1000 grams water = 1100.8 grams of solution,

so let's find the volume of this 110.8 gams of solution that has the 0.847 moles of KBr, using the density of 1.18 g/ml:

1100.8 grams sol'n @ 1 ml / 1.18 grams = 932.88 millilitres

now let's find the Molarity:

0.847 moles KBr / 0.9328 Litres sol'n = 0.9080 Molar

your answer (3sigfigs) : 0.908 Molar KBr