Question

A 32.0-g sample of HF is dissolved in water to give 2.0 × 102 mL of solution. The concentration of the solution is:

Answer 1

 The concentration of the  solution is  8 M

 calculation

 Concentration   =  moles/volume  in liters

 step 1: find moles of HF

moles  of HF  =mass/molar mass

molar mass of  HF =  1+  19 )= 20 g/mol

moles is  therefore = 32.0  g/ 20 g/mol= 1.6  moles

Step 2:  convert  ml to L

volume in liters = 2.0 x 10^2 / 1000 =0.2 l

step 3: find the concentration

concentration  =  1.6 mol  / 0.2 l = 8 M