Grade 10 · Science · Chemistry

10th grade Reactions that release or absorb energy worksheet

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Reactions that release or absorb energy

Grade 10 Science Worksheet - Challenge Me

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Circle the best answer, or write your answer on the line.

Forming liquid water from hydrogen releases 286 kJ per mole of water. How much heat is released when 3 mol of water forms, Ari?
Burning methane releases 890.8 kJ per mole. How much heat is released when 2 mol of methane burns, Bo?
Burning ethanol releases 1366.8 kJ per mole. How much heat is released when 0.5 mol of ethanol burns, Esme?
4.
Using the diagram, what is ΔH for this reaction, Jun?
- −40 kJ
- +40 kJ
- +80 kJ
5.
Milo says a cold pack is exothermic because heat leaves the hand. Agree or disagree?
- Agree: heat leaves the hand, so it's exothermic
- Disagree: the pack takes in that heat
- Agree: cold things give off cold
6.
Noah says a hand warmer is endothermic because the hand absorbs heat. Agree or disagree?
- Disagree: the warmer gives out heat
- Agree: the hand takes heat in, so it's endothermic
- Agree: iron soaks up the warmth
7.
Pia says an exothermic reaction needs no energy to get started. Agree or disagree?
- Disagree: it still has a hill
- Agree: heat comes out, so nothing goes in
- Agree: exothermic means no hill
8.
Per mole, methane burning has ΔH = −890.8 kJ and ethanol −1366.8 kJ. Which releases more heat per mole, Ren?
- They release the same
- Ethanol
- Methane
9.
Making liquid water releases 286 kJ per mole; making water vapor releases 242 kJ. Why is there a difference, Tala?
- Condensing also releases heat
- Vapor forms more slowly
- Vapor has no bonds in it
10.
H₂ + ½ O₂ → H₂O(l) has ΔH = −286 kJ. What is ΔH for 2 H₂ + O₂ → 2 H₂O(l), Zee?
- −572 kJ
- −286 kJ
- +572 kJ

10th grade Reactions that release or absorb energy worksheet – printable — Print: 1 2 3 4 5 6

About this worksheet

Reactions that release or absorb energy. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

I can tell exothermic (heat released, ΔH negative) from endothermic (heat absorbed, ΔH positive).
I can read ΔH and the activation energy from an energy diagram.
I can explain hand warmers and instant cold packs.
I can reverse a reaction's ΔH and scale it for more moles.

Standard: HS-PS1-4

Words to know

exothermic: Releasing heat to the surroundings; ΔH < 0

endothermic: Absorbing heat from the surroundings; ΔH > 0

enthalpy change, ΔH: Products' energy minus reactants' energy

activation energy: The climb from the reactants to the top of the hill

catalyst: A substance that lowers the hill without changing ΔH

Common mistakes

Your child subtracted the wrong way. ΔH is products minus reactants, so energy released gives a negative ΔH.

Your child measured the hill from the products. Activation energy is measured up from the reactants.

Your child divided by the moles. Burning more moles releases more heat, so multiply.

Questions parents ask

What is the most common mistake with reactions that release or absorb energy?

Your child subtracted the wrong way. ΔH is products minus reactants, so energy released gives a negative ΔH.

Are these 10th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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