All Free Chemistry MCQs with Answers
Every Chemistry question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
13,720 questions · page 508 of 686
- A. Enthalpy of reaction
- B. Enthalpy of formation
- C. Enthalpy of neutralization
- D. Enthalpy of combustion
Explanation: This equation shows the reaction of a strong acid (HCl) with a strong base (NaOH) to produce a salt (NaCl) and water.
Correct answer: Enthalpy of neutralization- A. Formation of compound
- B. Combustion
- C. Dissolution of ionic compound
- D. Dilution of a solution
Explanation: Combustion is defined as a rapid reaction with an oxidant, usually oxygen, to produce heat and light.
Correct answer: Combustion- A. 84,000 J
- B. -2000/4.2 J
- C. 2000/4.2 J
- D. -8400 J
Explanation: Using the formula q = mcΔT, where ΔT = Tfinal - Tinitial = 5°C - 25°C = -20°C, q = (100 g)(4.2 J/g°C)(-20°C) = -8400 J.
Correct answer: -8400 J- A. Glass calorimeter
- B. Bomb calorimeter
- C. Thermometer
- D. Manometer
Explanation: A bomb calorimeter is specifically designed for accurately measuring the heat of combustion.
Correct answer: Bomb calorimeter- A. m x s
- B. c x ∆T
- C. s x ∆T
- D. c x s x ∆T
Explanation: In a bomb calorimeter experiment, the heat released by the reaction (q) is absorbed by the entire calorimeter assembly (bomb, water…
Correct answer: c x ∆T- A. Remains unaffected
- B. Increases
- C. Decreases
- D. All of these are possible
Explanation: A larger charge-to-size ratio means ions are more highly charged and more tightly packed, which increases the strength of ionic bonding in…
Correct answer: Increases10147. One of the best applications of Hess's law to calculate the lattice energy of ionic compound is:
- A. Measurement of enthalpy change in a calorimeter
- B. Studying of first law of thermodynamics
- C. Born-Haber cycle
- D. Measurement of a heat of formation of a compound
Explanation: The Born-Haber cycle is a specific application of Hess's Law. It relates the lattice energy of an ionic compound (which cannot be measured…
Correct answer: Born-Haber cycle- A. Enthalpy of combustion
- B. Lattice energy of covalent compounds
- C. Lattice energy of ionic compounds
- D. Enthalpy of ionization
Explanation: The Born-Haber cycle is a powerful theoretical tool used in chemistry to indirectly calculate the lattice energy of an ionic solid.
Correct answer: Lattice energy of ionic compounds- A. ∆H° of the reaction depends on temperature
- B. ∆H° of reaction can be > or < zero
- C. ∆H° of catalyzed and uncatalyzed reaction is the same
- D. ∆H° is always < 0
Explanation: This statement is false. The standard enthalpy change (∆H°) can be positive for endothermic reactions (which absorb heat) or negative for…
Correct answer: ∆H° is always < 010150. Thermodynamics deals with:
- A. Spontaneous reaction
- B. Rate of reaction
- C. Heat of reaction
- D. Entropy of reaction
Explanation: Thermodynamics deals with the energy changes during chemical processes, especially the heat of reaction, enthalpy, entropy, and…
Correct answer: Heat of reaction- A. 4180 J
- B. 8360 J
- C. 25080 J
- D. 50160 J
Explanation: Heat q = m × c × ΔT = 200 × 4.18 × (50.0 - 20.0) = 25080 J.
Correct answer: 25080 J- A. Endothermic
- B. Exothermic
- C. Isothermic
- D. Adiabatic
Explanation: Exothermic reactions release heat, causing the surroundings to gain energy.
Correct answer: Exothermic- A. -890.3 kJ
- B. -604.5 kJ
- C. -445.1 kJ
- D. -668 kJ
Explanation: ΔHrnx = ΣΔHf (products) - ΣΔHf (reactants) = [-393.5 + 2(-285.8)] - [-74.8] = -890.3 kJ.
Correct answer: -890.3 kJ- A. 16700 J
- B. 33400 J
- C. 41800 J
- D. 83600 J
Explanation: Heat = m × ΔHfus = 50.0 × 334 = 16700 J.
Correct answer: 16700 J- A. -1124.8 kJ
- B. -562.4 kJ
- C. -206.4 kJ
- D. -1032.0 kJ
Explanation: ΔHrxn = [2(-285.8) + 2(-296.8)] - [2(-20.6)] = -1124.8 kJ.
Correct answer: -1124.8 kJ- A. - 40 kJ/mol
- B. -50 kJ/mol
- C. - 45 kJ/mol
- D. - 6 kJ/mol
Explanation: The enthalpy of formation of a compound is the heat change that results when one mole of the compound is formed from its elements in their…
Correct answer: - 45 kJ/mol- A. ΔH°sol - The enthalpy change is the amount of heat absorbed or evolved when one mole of a substance is dissolved in excess solvent
- B. ΔH comb- The enthalpy change when one mole of a substance is burnt in excess air
- C. ΔH°at - The enthalpy change when one mole of gaseous atoms is formed from its compound under standard conditions
- D. ΔH°n - The enthalpy change when one mole of water is formed by the reaction of one mole of H⁺ ions from an acid with one mole of OH⁻ ions from a base
Explanation: The "enthalpy of atomization" is a thermodynamic quantity that represents the energy change associated with the process of breaking a…
Correct answer: ΔH°at - The enthalpy change when one mole of gaseous atoms is formed from its compound under standard conditions- A. x
- B. x - y
- C. x + y
- D. y
Explanation: The difference in energy between products and reactants is x, and the activation energy for the reactants is y; therefore, in the reverse…
Correct answer: x + y- A. The reaction proceeds in the forward direction at 300 K
- B. At 1200 K, the reaction proceeds in the reverse direction
- C. At 300 K, Kp > 1
- D. At 300 K, the products will be favored more than reactants at equilibrium
Explanation: The correct answer is Option C because at 300 K; Kp > 1. In an exothermic reaction, decreasing the temperature shifts the equilibrium…
Correct answer: At 300 K, Kp > 1- A. +111 kJ/mol
- B. -111 kJ/mol
- C. -677 kJ/mol
- D. +677 kJ/mol
Explanation: According to Hess's Law: Direct Path = Indirect Path ΔH (C → CO₂) = ΔH (C → CO) + ΔH (CO → CO₂)Calculation: -394 = X + (-283) X = -394 +…
Correct answer: -111 kJ/mol