NEET Some Basic Concepts Of Chemistry — Set 15

Question 1

What is the mole fraction of $ \ce{H2O} $ in a solution containing 36 g of $ \ce{H2O} $ and 46 g of $ \ce{C2H5OH} $? (Molar masses: $ \ce{H2O} $ = 18 g/mol, $ \ce{C2H5OH} $ = 46 g/mol)

Accepted Answer

Moles of $ \ce{H2O} $ = $ \frac{36}{18} $ = 2 mol; moles of $ \ce{C2H5OH} $ = $ \frac{46}{46} $ = 1 mol. Total moles = 2 + 1 = 3. Mole fraction = $ \frac{2}{3} $ ≈ 0.667.

Question 2

A 200 mL solution contains 7.3 g of $ \ce{HCl} $ and has a density of 1.02 g/mL. What is its molarity? (Molar mass: $ \ce{HCl} $ = 36.5 g/mol)

Accepted Answer

Moles of $ \ce{HCl} $ = $ \frac{7.3}{36.5} $ = 0.2 mol. Volume = 200 mL = 0.2 L. Molarity = $ \frac{0.2}{0.2} $ = 1 M.

Question 3

What is the mass of $ \ce{SO3} $ produced when 16 g of $ \ce{SO2} $ reacts with 8 g of $ \ce{O2} $? (Molar masses: $ \ce{SO2} $ = 64 g/mol, $ \ce{SO3} $ = 80 g/mol, $ \ce{O2} $ = 32 g/mol)

Accepted Answer

Reaction: $ \ce{2SO2 + O2 -> 2SO3} $. Moles: $ \ce{SO2} $ = $ \frac{16}{64} $ = 0.25 mol, $ \ce{O2} $ = $ \frac{8}{32} $ = 0.25 mol. 2 mol $ \ce{SO2} $ need 1 mol $ \ce{O2} $; 0.25 mol $ \ce{SO2} $ need 0.125 mol $ \ce{O2} $ (available). 0.25 mol $ \ce{SO2} $ produces 0.25 mol $ \ce{SO3} $ = 0.25 × 80 = 20 g.

NEET Chemistry: Some Basic Concepts Of Chemistry — Practice Set 15

Q1. What is the mole fraction of \( \ce{H2O} \) in a solution containing 36 g of \( \ce{H2O} \) and 46 g of \( \ce{C2H5OH} \)? (Molar masses: \( \ce{H2O} \) = 18 g/mol, \( \ce{C2H5OH} \) = 46 g/mol)

Q2. A 200 mL solution contains 7.3 g of \( \ce{HCl} \) and has a density of 1.02 g/mL. What is its molarity? (Molar mass: \( \ce{HCl} \) = 36.5 g/mol)

Q3. What is the mass of \( \ce{SO3} \) produced when 16 g of \( \ce{SO2} \) reacts with 8 g of \( \ce{O2} \)? (Molar masses: \( \ce{SO2} \) = 64 g/mol, \( \ce{SO3} \) = 80 g/mol, \( \ce{O2} \) = 32 g/mol)

Q4. A gas occupies 1.12 L at STP and weighs 1.6 g. What is its molar mass?

Q5. How many liters of \( \ce{CO2} \) at STP are produced when 10 g of \( \ce{CaCO3} \) reacts with excess \( \ce{HCl} \) with 80% efficiency? (Molar mass: \( \ce{CaCO3} \) = 100 g/mol)

Q6. How many grams of \( \ce{CuSO4} \) are required to produce 3.2 g of \( \ce{Cu} \) with excess \( \ce{Zn} \)? (Molar masses: \( \ce{CuSO4} \) = 159.5 g/mol, Cu = 64 g/mol)

Q7. How many grams of \( \ce{H2SO4} \) are required to neutralize 8 g of \( \ce{NaOH} \) completely? (Molar masses: \( \ce{H2SO4} \) = 98 g/mol, \( \ce{NaOH} \) = 40 g/mol)

Q8. What volume of \( \ce{CO2} \) at STP is produced when 7 g of \( \ce{C2H2} \) is burned completely? (Molar mass: \( \ce{C2H2} \) = 26 g/mol)

Q9. A 3 L sample of a gas at STP weighs 3.75 g and contains only carbon and hydrogen. If it produces 5.28 g of \( \ce{CO2} \) on burning, what is its molecular formula? (Atomic masses: C = 12, H = 1)

Q10. What volume of \( \ce{CO2} \) at STP is produced when 11.2 g of \( \ce{C5H12} \) is burned completely? (Molar mass: \( \ce{C5H12} \) = 72 g/mol)