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Acid Meets Base

When an acid and a base mix, their reactive parts cancel each other out. What is left behind is a salt dissolved in water, with a pH close to 7.

In the picture

  1. Badge 1 sits on the glass barrel of the burette, which holds the acid being added drop by drop.
  2. Badge 2 sits on the conical flask of pink liquid, the base waiting to react.
  3. Badge 3 sits on the pH meter screen, reading 7.0 at the moment the two exactly cancel.
  4. Badge 4 sits on the watch glass of white crystals, the salt and water left after the reaction.

Examples

  • An antacid tablet neutralising stomach acid
  • Baking soda sprinkled over spilled vinegar

Quiz: Acid Meets Base (Age 16)

  1. When an acid and a base neutralise each other, what is left in the container?

    • A salt dissolved in water
    • A stronger acid and hydrogen gas
    • Two separate layers, one acid and one base
  2. A base is added drop by drop to an acid. What is the pH at the exact moment the two cancel each other out?

    • Close to 0, because a salt has formed
    • Close to 7, because no acid or base is left over
    • Above 12, because the base takes over
  3. Why does a fully neutralised mixture no longer behave like an acid or a base?

    • The acid evaporates and only water is left
    • The salt that forms traps the acid particles and hides them
    • The reactive parts of the acid and the base have combined with each other

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.

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Chemistry, Age 16