Chemistry · KS3 Y8 · Chemical Reactions

Exothermic & endothermic

Exothermic & endothermicFree4:18Heddy Score 3 of 7, below the standard
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What you need to know

  • Neutralising hydrochloric acid with sodium hydroxide is exothermic, so the temperature of the solution rises.
  • The independent variable is the volume of sodium hydroxide added, the dependent variable is the maximum temperature, and the acid volume and concentrations are controlled.
  • The maximum temperature rises as more alkali reacts, then falls once all the acid is used up, because the same energy is spread through a larger volume.
  • A polystyrene cup with a lid insulates the mixture and reduces heat loss, making the measurements more accurate.

In this clip

Runs 4:18, from 0:10 to 4:28 of the full video.

Heddy Score3/7, Below the standard
See the seven stars
  • Trusted source · passed. The creator's own upload, live and playable here.
  • On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
  • Spec-true · not judged yet. Accurate, and right for the current UK specification.
  • Focused · passed. One idea, short enough to watch in one go.
  • Accessible · passed. Good captions, clear sound and pictures.
  • Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
  • Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
★ passed · ☆ pending · ✕ failed
Our students

Not enough students yet

Our own students' answers. These are what move ★7 Proven.
On YouTube

901K views · Freesciencelessons 995K subscribers

As reported by YouTube on 2026-11-02. Not part of the Heddy Score.
How the Heddy Score works

Why we picked it

A clear walk-through of the GCSE required practical on temperature change in an exothermic neutralisation, including the reasons behind the method.

Freesciencelessons on YouTubechecked 2026-10-22

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