Need help! I have to calculate the volume but what does the w/w and the percents mean?

Question

Adipoyl Chloride 5% (w/w) in cyclohexane (It says to use 15 mL of this stuff & density is 1.2500, & formula weight is 183.03)

Cyclohexane from the above solution (formula weight is 84.16 and density is 0.770)

Answer 1

The w/w means weigh to weigh, so 5% (w/w) means 5 g/100 g of solution (recall that % means "out of 100"). If it were 5% (w/v), which means weight to volume, it would be 5 g/100 mls of solution. So, in this question, you have a solution that is 5 g of adipoyl chloride in 100 g of solution. You ask for help to calculate the volume, but the problem already gives you the volume. It tells you to use 15 ml. That's the volume!! What you probably are asking is "what volume of cyclohexane do you need.

For the adipoyl chloride, 15 ml x 1.2500 g/ml = 18.75 g of adipoyl chloride used

Since you want 5%, we need to figure out how much cyclohexane this should be put into.

5 g adipoyl Cl/100 g cyclohexane = 18.75 g adipoyl Cl/x g cyclohexane and x = 375 g of cyclohexane needed

375 g cyclohexane x 1 ml/0.770 g = 487 ml of cyclohexane needed