NEET Some Basic Concepts Of Chemistry — Set 7

Question 1

What volume of $ \ce{N2} $ at STP is required to react with 4 g of $ \ce{H2} $ to produce $ \ce{NH3} $ with 100% yield? (Molar mass: $ \ce{H2} $ = 2 g/mol)

Accepted Answer

Reaction: $ \ce{N2 + 3H2 -> 2NH3} $. Moles of $ \ce{H2} $ = $ \frac{4}{2} $ = 2 mol. 3 mol $ \ce{H2} $ need 1 mol $ \ce{N2} $; 2 mol need $ \frac{1}{3} $ × 2 ≈ 0.6667 mol. Volume = 0.6667 × 22.4 ≈ 14.93 L.

Question 2

A gas occupies 4.48 L at STP and weighs 6.4 g. What is its molar mass?

Accepted Answer

Moles = $ \frac{4.48}{22.4} $ = 0.2 mol. Molar mass = $ \frac{6.4}{0.2} $ = 32 g/mol.

Question 3

What is the mass of water produced when 8 g of $ \ce{CH4} $ reacts with 24 g of $ \ce{O2} $? (Atomic masses: C = 12, H = 1, O = 16)

Accepted Answer

Reaction: $ \ce{CH4 + 2O2 -> CO2 + 2H2O} $. Moles: $ \ce{CH4} $ = $ \frac{8}{16} $ = 0.5 mol, $ \ce{O2} $ = $ \frac{24}{32} $ = 0.75 mol. 0.5 mol $ \ce{CH4} $ needs 1 mol $ \ce{O2} $; $ \ce{O2} $ limits at 0.375 mol $ \ce{CH4} $. 0.375 mol $ \ce{CH4} $ produces 0.75 mol $ \ce{H2O} $ = 13.5 g.

NEET Chemistry: Some Basic Concepts Of Chemistry — Practice Set 7

Q1. What volume of \( \ce{N2} \) at STP is required to react with 4 g of \( \ce{H2} \) to produce \( \ce{NH3} \) with 100% yield? (Molar mass: \( \ce{H2} \) = 2 g/mol)

Q2. A gas occupies 4.48 L at STP and weighs 6.4 g. What is its molar mass?

Q3. What is the mass of water produced when 8 g of \( \ce{CH4} \) reacts with 24 g of \( \ce{O2} \)? (Atomic masses: C = 12, H = 1, O = 16)

Q4. A 2 L sample of a gas at STP weighs 1.4 g and contains only carbon and hydrogen. If it produces 4.4 g of \( \ce{CO2} \) on burning, what is its molecular formula? (Atomic masses: C = 12, H = 1)

Q5. What is the mass percentage of \( \ce{NH4Cl} \) in a solution made by dissolving 10.7 g of \( \ce{NH4Cl} \) in 39.3 g of water? (Molar mass: \( \ce{NH4Cl} \) = 53.5 g/mol)

Q6. A 0.5 L sample of a gas at STP weighs 0.67 g and contains only carbon and hydrogen. If it produces 1.32 g of \( \ce{CO2} \) on burning, what is its molecular formula? (Atomic masses: C = 12, H = 1)

Q7. A 0.70 g sample of a hydrocarbon produces 2.20 g of \( \ce{CO2} \) and 0.90 g of \( \ce{H2O} \) on complete combustion. What is its molecular formula if its molar mass is 70 g/mol? (Atomic masses: C = 12, H = 1, O = 16)

Q8. A 0.2 M \( \ce{NaCl} \) solution is diluted by adding 150 mL of water to 50 mL of the original solution. What is the final molarity?

Q9. A compound contains 24% magnesium, 28% sulfur, and 48% oxygen by mass. What is its empirical formula? (Atomic masses: Mg = 24, S = 32, O = 16)

Q10. A mixture of 4 g \( \ce{H2} \) and 56 g \( \ce{N2} \) is used to synthesize \( \ce{NH3} \). What is the maximum mass of \( \ce{NH3} \) produced? (Molar masses: \( \ce{H2} \) = 2 g/mol, \( \ce{N2} \) = 28 g/mol, \( \ce{NH3} \) = 17 g/mol)