Question

A solution is made by dissolving 17.2 g of ethanol, CH3CH2OH, in enough water to make exactly 500 mL of solution. What is the concentration (molarity) of CH3CH2OH in mol/L

Answer 1

0.748M

Step-by-step explanation:

Molarity is defined as the ratio between moles of solute (The substance in the lower amount, ethanol) and liters of solution.

To solve the problem we need to convert the mass of ethanol to moles using its molar mass and the mL of solution to liters:

Moles ethanol:

molar mass:

C₂H₆O:

2C = 2*12g/mol = 24g/mol

6H = 6*1g/mol = 6g/mol

O = 16g/mol

Molar mass: 24 + 6 + 16 = 46g/mol

Moles are:

17.2g * (1mol / 46g) = 0.374 moles

Volume of solution:

500mL * (1L / 1000mL) = 0.500L

Molarity:

0.374moles / 0.500L =

0.748M