Reactions that release or absorb energy
Grade 10 Science Worksheet
Circle the best answer, or write your answer on the line.
An energy diagram shows the reactants at 50 kJ, the top of the hill at 130 kJ and the products at 90 kJ. What is the activation energy, Bo?
An energy diagram shows the reactants at 200 kJ, the top of the hill at 260 kJ and the products at 150 kJ. What is the activation energy, Esme?
H₂ + Cl₂ → 2 HCl has ΔH = −184.6 kJ. What is ΔH for 2 HCl → H₂ + Cl₂, Jun?
- +184.6 kJ
- −184.6 kJ
- 0 kJ
In a reusable hand warmer, sodium acetate crystallizing is exothermic. What happens when it is reheated to redissolve, Luz?
- No heat moves
- It absorbs heat
- It releases heat
Where does an instant cold pack get the heat it absorbs, Milo?
- From the empty air inside it
- From the skin and surroundings
- From the ammonium nitrate itself
An exothermic reaction happens in water. What happens to the water's temperature, Noah?
- It falls
- It stays the same
- It rises
Ammonium nitrate dissolves and the water cools from 24.9 °C to 20.3 °C. Is the dissolving exothermic or endothermic, Pia?
- Endothermic: the water cooled
- Exothermic: the solid vanished
- Exothermic: the water cooled
On an energy diagram, what does a catalyst change, Ren?
- It lowers the hill
- It changes ΔH
- It raises the products
Burning a match is exothermic. Why must it be struck before it burns, Tala?
- Striking adds the products
- It must climb the hill first
- Burning is endothermic
Reaction A has ΔH = −50 kJ and reaction B has ΔH = −200 kJ. Which releases more heat, Zee?
- Reaction B
- They release the same
- Reaction A