Ethanol is a common laboratory solvent and has a density of 0.789 g/mL. What is the mass, in grams, of 145 mL of ethanol?

Answer 1

You are given the density of 0.789 g/mL Multiplying by the number of mL will give you grams as an answer, so

(0.789 g/mL) * 145 mL = 114.405 grams. Each of the numbers given to you in the problem has three significant figures, so you must express your final answer to three significant figures. The final answer is :

114 grams

Answer 2

The relationship you need: Density = ^mass/_volume or D = ^m/_V

Given: D = 0.789 g/mL

V = 145 mL

Asked: m = ?

Rearrange the equation to solve for m by multiplying each side by V: m = D x V

m = 0.789 ^g/_mL x 145 mL = 114 g