Question

What is the molarity of a solution of 17.0 g of nh4br in enough h2o to make 158 ml of solution? answer in units of m?

Answer 1

Unit of M is also mole/L, where mole is the moles of solute and L is the volume of the solution.  The latter is given: 158 mL or 0.158 L.  So we need to find out the moles of NH4Br.

Moles of NH4Br = Mass of NH4Br/molar mass of NH4Br = 17.0g/(14+1*4+79.9)g/mol = 0.1736 mole.

So, the molarity of the solution = 0.1736mole/0.158L = 1.10 mole/L = 1.10 M