Answer:
a. 7.187M.
b. 7.962m.
c. 0.1846
Explanation:
This solution contains 42.55mL of ethyl alcohol in 100mL of solution.
a. Molar concentration = Moles ethyl alcohol / L solution:
<em>Moles ethyl alcohol -Molar mass: 46.07g/mol-</em>
42.55mL * (0.7782g/mL) * (1mol / 46.07g) = 0.7187 moles ethyl alcohol
<em>Liters solution:</em>
100mL * (1L / 100mL) = 0.100L
Molar concentration: 0.7187mol / 0.100L = 7.187M
b. Molal concentration: Moles ethyl alcohol (0.7187moles) / kg solution
<em>kg solution:</em>
100mL * (0.9027g / mL) * (1kg / 1000g) = 0.09027kg
Molal concentration: 0.7187mol / 0.09027kg = 7.962m
c. Mole fraction: Moles ethyl alcohol / Moles ethyl alcohol + moles water
<em>Moles water: -molar mass: 18.01g/mol-</em>
Volume water = 100mL - 42.55mL = 57.45mL
57.45mL * (0.9949g/mL) * (1mol/18.01g) = 3.1736 moles water
<em>Moles fraction:</em>
0.7187 moles ethyl alcohol / 0.7187 moles ethyl alcohol+3.1736 moles water
= 0.1846
