Question

Desonate gel contains 0.05% w/w desonide. Calculate (a) the quantity of this agent, in grams, in each 60-g tube of product and (b) the concentration of desonide, in mg/g of gel.

Answer 1

% w/w denotes 1 g of solute in 100 g of solution. Therefore, 0.05 % w/w means 0.05 g of desonide in 100 g of desonate gel.

100 g solution(/gel/tube) has 0.05 g of desonide

1 g of desonate gel has 0.05/100 g of desonide

Therefore, 60 g tube will contain 0.05/100 X 60 g of desonide = (0.05 X 60)/100 = 0.03 g

1. Hence, each tube of 60 g of product will contain 0.03 g of desonide.

We know, 1 g of desonate gel has 0.05/100 (0.0005) g of desonide (shown above)

1 g = 1000 mg

So, 0.0005 g = 1000 X 0.0005 mg = 0.5 mg

2. Therefore, 1 g of desonate has 0.5 mg of desonide. Concentration of desonide, in mg/g of gel is 0.5 mg/g.