Question

Solve this:
Q. What will be the molarity of pure ethanol if density of pure ethanol is 789 kg/m3 at 298 K?
A. 17.15 M
B. 23 M
C. 11.5 M
D. 5.75 M

Answer 1

17.15M

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Answer 2

Answer: Molarity of pure ethanol is 17.15 M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n= moles of solute

 $V_s$ = volume of solution in ml

Given : Density of pure ethanol = $789kg/m^3$

Thus 789 kg of ethanol is dissolved in $1m^3$ of the solution.

moles of ethanol =$\frac{\text{Given mass}}{\text{Molar mass}}=\frac{789\times 1000g}{46g/mol}=17152mole$  

Volume of solution = $1m^3=1000000ml$

$Molarity=\frac{17152\times 1000}{1000000}=17.15M$

Thus molarity of pure ethanol is 17.15 M