Energy changes questions

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Energy changes question collection

Review Energy changes questions for Chemistry, with correct answers shown and coverage across exothermic and endothermic reactions; reaction profile diagrams; activation energy.

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Question 1

An exothermic reaction transfers energy?
  1. To the surroundings
  2. From the surroundings
  3. Only to the reactants
  4. Only to catalysts

Question 2

An endothermic reaction transfers energy?
  1. From the surroundings
  2. To the surroundings
  3. Only to products
  4. Only as light

Question 3

What usually happens to the temperature of the surroundings during an exothermic reaction?
  1. It increases
  2. It decreases
  3. It stays exactly the same
  4. It becomes \(0\,\mathrm{^\circ C}\)

Question 4

What usually happens to the temperature of the surroundings during an endothermic reaction?
  1. It decreases
  2. It increases
  3. It stays exactly the same
  4. It always reaches \(100\,\mathrm{^\circ C}\)

Question 5

Which process is typically exothermic?
  1. Combustion
  2. Thermal decomposition
  3. Photosynthesis
  4. Melting

Question 6

Which process is typically endothermic?
  1. Thermal decomposition
  2. Condensation
  3. Freezing
  4. Neutralisation

Question 7

Is \(\text{acid} + \text{alkali} \to \text{salt} + \text{water}\) usually exothermic or endothermic?
  1. Exothermic
  2. Endothermic
  3. Neither exothermic nor endothermic
  4. Always reversible only

Question 8

Photosynthesis is best described as?
  1. Endothermic because it takes in light energy
  2. Exothermic because it gives out oxygen
  3. Exothermic because glucose stores heat
  4. Neither because plants are living

Question 9

Respiration in cells is overall?
  1. Exothermic
  2. Endothermic
  3. Only physical, not chemical
  4. Always neutral in energy terms

Question 10

Breaking chemical bonds requires?
  1. An input of energy
  2. Release of energy only
  3. No energy change
  4. Only a catalyst and no energy

Question 11

Does making chemical bonds usually release or absorb energy?
  1. Releases energy
  2. Absorbs energy only
  3. Has no energy change
  4. Always needs electrical energy input

Question 12

A reaction is exothermic when?
  1. Energy released by bond making is greater than energy absorbed by bond breaking
  2. Energy absorbed is greater than energy released
  3. No bonds are broken or made
  4. The reaction happens very slowly

Question 13

On an exothermic reaction profile, are the products at a higher or lower energy than the reactants?
  1. At a lower energy level than the reactants
  2. At a higher energy level than the reactants
  3. At exactly the same energy level
  4. Not shown on the graph

Question 14

What is activation energy?
  1. The minimum energy needed for particles to react
  2. The total energy released in all reactions
  3. The energy stored in products only
  4. The energy needed to cool a reaction

Question 15

How does a catalyst speed up a reaction?
  1. It provides an alternative pathway with lower activation energy
  2. It increases the mass of reactants
  3. It raises the energy of products
  4. It is used up to release extra heat

Question 16

Which setup is best for measuring temperature change in a simple school reaction?
  1. An insulated cup with a thermometer
  2. An open tray with no thermometer
  3. A metal beaker with no lid and no timing
  4. A sealed tube with no temperature reading

Question 17

Which change of state is endothermic?
  1. Melting
  2. Freezing
  3. Condensation
  4. Deposition

Question 18

Which change of state is exothermic?
  1. Condensation
  2. Boiling
  3. Sublimation
  4. Melting

Question 19

Why do instant cold packs feel cold?
  1. Endothermic
  2. Exothermic
  3. Combustion
  4. Neutralisation only

Question 20

What is the symbol equation for the burning of methane?
  1. \(\mathrm{CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O}\)
  2. \(\mathrm{CH_4 + O_2 \rightarrow CO + H_2}\)
  3. \(\mathrm{CH_4 + 2O_2 \rightarrow C + 2H_2O}\)
  4. \(\mathrm{2CH_4 + O_2 \rightarrow 2CO_2 + 2H_2O}\)

Question 21

An exothermic reaction transfers energy?
  1. To the surroundings
  2. From the surroundings
  3. Only to catalysts
  4. Only to reactants

Question 22

An endothermic reaction transfers energy?
  1. From the surroundings
  2. To the surroundings
  3. Only as light to the room
  4. Only into products with no surroundings effect

Question 23

On an exothermic reaction profile, are the products at a higher or lower energy than the reactants?
  1. At a lower energy level than the reactants
  2. At a higher energy level than the reactants
  3. At the same energy level as reactants always
  4. Not shown on the profile

Question 24

What is activation energy?
  1. The minimum energy needed for reacting particles to react
  2. The total energy released by products
  3. The energy stored only in catalysts
  4. The energy needed to cool reactants

Question 25

How does a catalyst speed up a reaction?
  1. By providing an alternative pathway with lower activation energy
  2. By increasing the overall energy change, ΔH
  3. By being used up to release heat
  4. By increasing reactant mass

Question 26

Breaking chemical bonds requires?
  1. An input of energy
  2. Release of energy only
  3. No energy change
  4. Only a change in pH

Question 27

Does making chemical bonds usually release or absorb energy?
  1. Releases energy
  2. Absorbs energy only
  3. Has no energy change
  4. Always requires electrical input

Question 28

For bond energy calculations, how is the overall energy change found?
  1. Energy to break bonds - energy released making bonds
  2. Energy released making bonds - energy to break bonds
  3. Energy to break bonds + energy released making bonds
  4. Energy to break bonds x energy released making bonds

Question 29

If more energy is released making bonds than absorbed breaking bonds, is the reaction exothermic or endothermic?
  1. Exothermic
  2. Endothermic
  3. Neutral with ΔH = 0 always
  4. Impossible to predict

Question 30

In simple calorimetry, the equation used is q =?
  1. m c ΔT
  2. m / c ΔT
  3. m c / ΔT
  4. m + c + ΔT

Question 31

\(100\,\mathrm{g}\) of water is heated by \(5\,\mathrm{^\circ C}\). Use \(c = 4.2\,\mathrm{J\,g^{-1}\,^\circ C^{-1}}\). What is \(q\)?
  1. \(2100\,\mathrm{J}\)
  2. \(840\,\mathrm{J}\)
  3. \(21000\,\mathrm{J}\)
  4. \(500\,\mathrm{J}\)

Question 32

Which reaction type is usually exothermic?
  1. Neutralisation of an acid and an alkali
  2. Thermal decomposition
  3. Photosynthesis
  4. Electrolysis of molten salts only

Question 33

Which process is usually endothermic?
  1. Thermal decomposition of calcium carbonate
  2. Combustion of methane
  3. Respiration
  4. Condensation of steam

Question 34

A chemical cell produces electricity from what type of reaction?
  1. A redox reaction between different materials
  2. Only thermal decomposition
  3. Only acid-base neutralisation
  4. A physical change of state only

Question 35

When does a cell made from two metals give a higher voltage?
  1. Further apart in reactivity
  2. Next to each other in reactivity
  3. Both equally unreactive
  4. Identical metals in identical conditions

Question 36

Why can a rechargeable battery be recharged?
  1. An external current can reverse the chemical reactions
  2. Its reactants are never used at all
  3. It continuously creates new metals
  4. It uses only exothermic reactions

Question 37

In a hydrogen fuel cell, hydrogen reacts with oxygen to form?
  1. Water
  2. Hydrogen peroxide
  3. Carbon dioxide
  4. Methane

Question 38

What is one advantage of hydrogen fuel cells at point of use?
  1. They produce water rather than carbon dioxide
  2. They require no fuel input
  3. They always generate electricity forever
  4. They never involve any safety concerns

Question 39

On reaction profiles, what sign is ΔH for exothermic reactions?
  1. Negative
  2. Positive
  3. Always zero
  4. Always greater than activation energy

Question 40

Why are bond energies quoted as average values?
  1. Bond energy can vary slightly in different compounds
  2. All bonds of a type have exactly the same energy in all molecules
  3. Bond energies depend only on color of the substance
  4. Bond energy is measured once and never recalculated

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Review Energy changes questions for Chemistry, with correct answers shown and coverage across exothermic and endothermic reactions; reaction profile diagrams; activation energy.

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