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 - Building Confidence

NameDate

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

An energy diagram shows the reactants at 50 kJ and the products at 90 kJ. What is ΔH, Bo?
An energy diagram shows the reactants at 200 kJ and the products at 150 kJ. What is ΔH, Esme?
Read this first
Energy diagram: a hill from reactants to products (example values)
point energy (kJ)
reactants 120
top of the hill 180
products 40
3.
Using the diagram, what is the climb from the reactants to the top called, Kira?
- Activation energy
- Enthalpy change
- Bond length
4.
Using the diagram, what sign does ΔH have, Luz?
- Negative
- Zero
- Positive
5.
An opened hand warmer gets warm as iron reacts with oxygen. Is that exothermic or endothermic, Milo?
- Endothermic: it is a solid
- Endothermic: it releases heat
- Exothermic: it releases heat
6.
An instant cold pack feels cold as ammonium nitrate dissolves. Is that exothermic or endothermic, Noah?
- Exothermic: it absorbs heat
- Exothermic: it feels cold
- Endothermic: it absorbs heat
7.
Methane burns in a gas stove's flame. Is that exothermic or endothermic, Pia?
- Neither one
- Exothermic
- Endothermic
8.
Forming liquid water from hydrogen and oxygen has ΔH = −286 kJ. What does the minus sign mean, Ren?
- No heat moves
- Heat is absorbed
- Heat is released
9.
What sign does ΔH have for an endothermic reaction, Tala?
- Positive
- Exactly zero
- Negative
10.
Where does the heat from an exothermic reaction go, Zee?
- Back into the reactants
- Nowhere: it vanishes
- Into the surroundings

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

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

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

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.

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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