Question

5g of an unknown solute is dissolved in 295g solvent if molarity and density of solution is 0.05 M and 1.5 g the molecular weight of unknown solute is

Answer 1

mass of the solution=5+295=300g.

Molarity=weight of solute×1000/molar mass×volume of solution(ml)

Answer 2

Answer: The molecular weight of unknown solute is 500 g/mol.

Explanation:

We are given:

Mass of solute = 5 g

Mass of solvent = 295 g

Mass of solution = [295 + 5] = 300 g

Density of solution = 1.5 g/mL

To calculate the volume of solution, we use the equation:

$\text{Density}=\frac{\text{Mass}}{\text{Volume}}$

Putting values in above equation, we get:

$1.5g/mL=\frac{300g}{\text{Volume}}\\\\\text{Volume of solution}=200mL$

To calculate the molecular mass for given value of molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

We are given:

Mass of solute = 5 g

Molarity of solution = 0.05 mol/L

Volume of solution = 200 mL

Putting values in above equation, we get:

$0.05mol/L=\frac{5g\times 1000}{\text{Molecular weight of solute}\times 200mL}\\\\\text{Molecular weight of solute}=500g/mol$

Hence, the molecular weight of unknown solute is 500 g/mol.