Hey guys! Here's the question:

A 48 wt% solution of HBr in water has a density of 1.50 g/mL.

a) What mass of solution contains 36 g of HBr?
b) What volume of solution contains 233 mmol of HBr?
c) How much solution is required to prepare 0.250 L of 0.160 M HBr?

Thank you!

a) Find 48% of HBr in your density. This will give you the weight of HBr for each mL of water.

Such weight of HBr is in 1 mL, you can find how much water contains 36 g of HBr by proportions.

b) Convert the weight of HBr per mL of water into moles of HBr per mL of water, using the molar mass of HBr. Then, do the same as before, that is, use proportions.

c) First, find the amount of HBr which you have to have in your 0.250 L of water using the concentration given. From that amount, you can work out how much solution is required.

Say you need x moles of HBr in 0.250 L.
The concentration of your solution of HBr is y mol/mL
Do x/y to find the volume of solution required.