Let’s go through the worksheet step by step. We’re filling in blanks using words from the box. Some words can be used more than once.
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1. During a chemical reaction what is always transferred?
→ Energy is always transferred during a chemical reaction — either released or absorbed.
✔ Answer:
energy
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2. Described what is meant by the “conservation of energy” - In a chemical reaction energy cannot be _______ or _______.
→ Conservation of energy means energy isn’t created or destroyed — it just changes form.
✔ Answers:
created,
destroyed
*(Note: The word “created” and “destroyed” are both in the box.)*
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3. How is energy transferred in chemical reactions? - Through the breaking of chemical bonds in the ________ and creating new bonds in the ________.
→ Bonds break in reactants (starting materials), new bonds form in products (what you end up with).
✔ Answers:
reactants,
products
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4. What name is given to reactions that transfer energy to the surroundings?
→ These release heat — they’re called exothermic.
✔ Answer:
exothermic
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5. How do you know that an exothermic reaction has taken place? - Through an ________ in temperature from the reactants to the products.
→ Exothermic reactions make things hotter → temperature increases.
✔ Answer:
increase
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6. What is the name given to chemical reactions that transfer energy from the surroundings to the reactants?
→ These absorb heat — they’re called endothermic.
✔ Answer:
endothermic
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7. Name 2 examples of an exothermic reaction. - oxidation, _______________, _______________ or neutralisation
→ Common exothermic reactions: combustion (burning), respiration (in cells), oxidation (like rusting), neutralisation (acid + base).
We already have “oxidation” and “neutralisation”. So we need two more from the list.
From the box:
combustion,
respiration
✔ Answers:
combustion,
respiration
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8. Name 2 examples of an endothermic reaction - _______________, sodium hydrogen-carbonate and citric acid or thermal decomposition
→ Endothermic reactions absorb heat. Examples: photosynthesis (plants use sunlight), thermal decomposition (breaking down with heat), mixing baking soda and citric acid feels cold.
The blank is before “sodium hydrogen-carbonate...” — so likely looking for another common one.
From the box:
photosynthesis fits perfectly.
Also, “thermal decomposition” is already mentioned at the end — so maybe the first blank is
photosynthesis.
But wait — the sentence says: “Name 2 examples... - _______________, sodium hydrogen-carbonate and citric acid or thermal decomposition”
That seems like it’s listing three things? But the instruction says “name 2 examples”.
Looking again: It probably means:
- One example: [blank]
- Another example: sodium hydrogen-carbonate + citric acid OR thermal decomposition
So the blank should be
photosynthesis — which is clearly endothermic.
✔ Answer:
photosynthesis
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Now let’s compile all answers in order:
1. energy
2. created, destroyed
3. reactants, products
4. exothermic
5. increase
6. endothermic
7. combustion, respiration
8. photosynthesis
All words are from the box and fit correctly.
Final Answer:
energy; created, destroyed; reactants, products; exothermic; increase; endothermic; combustion, respiration; photosynthesis
Parent Tip: Review the logic above to help your child master the concept of exothermic vs endothermic worksheet.
