NEET Solutions — Set 16

Question 1

A solution contains 9 g of a solute (molar mass = 90 g/mol) in 450 mL of solution. What is the molarity?

Accepted Answer

Moles of solute = $ \frac{9}{90} = 0.1 \, \text{mol} $. Volume = 450 mL = 0.45 L. Molarity = $ \frac{0.1}{0.45} \approx 0.2222 \, \text{M} $.

Question 2

What is the molarity of a solution containing 9 g of glucose (molar mass = 180 g/mol) in 500 mL of solution?

Accepted Answer

Moles of glucose = $ \frac{9}{180} = 0.05 \, \text{mol} $. Volume = 500 mL = 0.5 L. Molarity = $ \frac{0.05}{0.5} = 0.1 \, \text{M} $.

Question 3

A solution of 10 g of a non-volatile solute in 400 g of water has a boiling point elevation of 0.13°C. What is the molar mass of the solute? ($ K_b = 0.52 \, \text{K kg mol}^{-1} $)

Accepted Answer

$ \Delta T_b = K_b \cdot m $. $ 0.13 = 0.52 \times \frac{\text{moles}}{0.4} $. Moles = $ \frac{0.13 \times 0.4}{0.52} = 0.1 $. Molar mass = $ \frac{10}{0.1} = 100 \, \text{g/mol} $.

NEET Chemistry: Solutions — Practice Set 16

Q1. A solution contains 9 g of a solute (molar mass = 90 g/mol) in 450 mL of solution. What is the molarity?

Q2. What is the molarity of a solution containing 9 g of glucose (molar mass = 180 g/mol) in 500 mL of solution?

Q3. A solution of 10 g of a non-volatile solute in 400 g of water has a boiling point elevation of 0.13°C. What is the molar mass of the solute? (\( K_b = 0.52 \, \text{K kg mol}^{-1} \))

Q4. What is the mass percentage of a solution if 5 g of a solute is dissolved in 45 g of water?

Q5. A solution is prepared with 46 g of ethanol (molar mass = 46 g/mol) and 54 g of water. If the mole fraction of ethanol becomes 0.4 after adding more ethanol, what mass of ethanol was added?

Q6. A solution contains 32 g of methanol (molar mass = 32 g/mol) and 90 g of water. If the mole fraction of methanol is to be increased to 0.3 by adding methanol, what mass of methanol is added?

Q7. How many grams of KCl (molar mass = 74.5 g/mol) are needed to prepare 250 mL of a 0.4 M solution?

Q8. What is the osmotic pressure of a 0.02 M solution of a non-electrolyte at 27°C? (\( R = 0.0821 \, \text{L atm mol}^{-1} \text{K}^{-1} \))

Q9. A 0.2 molal solution of a solute in water has a freezing point depression of 0.744°C. If the solute dissociates into 2 ions, what is the degree of dissociation? (\( K_f = 1.86 \, \text{K kg mol}^{-1} \))

Q10. A solution of two volatile liquids has vapor pressures of 180 mm Hg and 240 mm Hg for pure components. If the total vapor pressure is 216 mm Hg, what is the mole fraction of the second component?