Question

A 12 molar hcl solution contains 37% hcl by mass

Answer 1

First part is to find how many moles of HCL is there in 750 ml (which is 0.750L) in 0.0500 M HCl solution: 0.750 l x 0.0500 mol/L=0.0375 mol. Then, we convert this to grams by multiplying 0.0375 moles with 36.46 g/moles (which is the molar mass of HCl), and this gives us 1.37 grams of HCL, but you know the solution is 37% (or 0.37) which means that there is 37g of HCL in every 100 grams of solution. To see how many grams of your 37% HCL solution you need, you divide 1.37/0.37=3.70 grams. To convert this to ml, you use density.: 3.70 g / (1.2 g/ml) = 3.08 ml of 37% HCL and the rest is water (750-3.08=746.91 ml of water)