Question

How many grams of a 5% sulfur ointment must be mixed with 180 grams of 20% sulfur ointment to prepare an 8% sulfur ointment?

Answer 1

To make 1000 ml of solution , 50 ml of sulfur ointment is used to make a 5% solution. Remember, if you're diluting a liquid compound, you just have to subtract out the volume of liquid is being added to dilute & from the final volume : 1000 ml – 50 ml = 950 ml of solvent.

Here 1000x5/100=50 ml of sulfur ointment

Therefore,

1000x8/100=80 ml of sulfur ointment (8%)

1000x20/100=200 ml of sulfur ointment (20%)

[ (50 ml per litre X g of sulfur ointment )] +[ 200 ml per litre x 180 g of sulfur ointment)] = (80 ml per litre)

50x + 9000 = 80

X = (80 – 9000)/50 = -178.4 g

-178.4 g of sulfur ointment of a 5% sulfur ointment must be mixed with 180 grams of 20% sulfur ointment to prepare an 8% sulfur ointment.

[Note : You can not produce 8% solution by adding 5% in 20% solution you need to dilute 20% solution with solvent in which solution is made]