# Question: zinc and castor oil ointment zinc oxide 75 g castor...

###### Question details

ZINC AND CASTOR OIL OINTMENT

Zinc oxide 7.5 g

castor oil 50.0g

cetostearyl alcohol 2.0 g

white beeswax 10.0 g

arachis oil 30.05 g

The Wt/mL of castor oil is 0.95g

The volume of castor oil required to make 500 g of this ointment is?

***The answer that I was given was this: but I DO NOT understand why we got 1/0.95? why do we divide 1 by 0.95? does'nt wt/ml mean weight by mL? I thought it means 0.95/1 mL and not vise versa***

For 100 grams of the ointment, we need 50 grams of castor oil is required ( carefully watch the values).

For 500 grams of the ointment, we will need castor oil= 50/100*500= 2500 grams of castor oil.

As we are given, 0.95g of castor oil in 1 ml of castor oil.

So 2500 grams of castor oil is 1/0.95*2500 which is equal to 263 mL.