Question

The density of rubbing alcohol is 0.785g/mL at 25℃.

Calculate the mass of 15.0 mL of the rubbing alcohol.
Calculate the volume of 15.0 g of the rubbing alcohol.

Answer 1

Answer: The temperature is there to confuse you on purpose. Density changes with temp, but in these type of problems, they mean nothing

Explanation:

The formula for density is mass per unit of volume.

$D=m/v$

We dont have to do any conversions here so it boils down to division and multiplication.

$0.785g/mL=mass/15mL\\0.785g/mL*15mL = mass\\=11.78 grams$

Now for the second part:

$0.785g/mL=15g/volume\\15g/0.785g/mL = volume\\=19.11mL$