Question

How much urea is needed to prepare 18 g of the following formulation ?Urea 20g Propylene glycol 20 mLCrème base as 60g

Answer 1

Matter and Change - Mixture

A mixture is a combination of two or more substances in any proportion that do not combine chemically. In this case urea, propylen glycol and crème base.

Answer:

First we calculate the mass of the formulation as it is origynally prepared:

For this we calculate the mass of propylene glycol using its density (1.04 g/ml):

`m=Vx\delta=20mlx1.04(g)/(ml)=20.8g`

Now we calculate the total mass:

`m=20g+20.8g+60g=100.8g`

Now we know that 20g of urea are used to prepare 100.8g of the formulation, so we calculate the mass for 18g of the formulation:

`m=18gx(20gurea)/(100.8g)=3.57g\text{ }urea`

So the answer is 3.57g of urea.