Acids and bases game: the pH scale with things from home
A chemistry game that turns the pH scale from a list of numbers into the kitchen and the cleaning cupboard. A household substance appears — lemon juice, cola, milk, seawater, bleach — and you tap or drag the marker to its place on a 0 to 14 strip, painted in universal indicator colours. On easy you only need to say whether it is acidic, neutral or basic; on medium you must land within 1.5 of its real pH, and on hard within 1 with a grey strip, because the colour only appears when corrected. There are 26 substances, from battery acid to caustic soda, and each one leaves a concrete fact when you answer.
Chemistry · Primary, Secondary
Knowing that below 7 is acidic is not much use without knowing where vinegar or toothpaste falls. Placing things the student has actually handled turns the scale into a map with landmarks: lemon at 2, water at 7, bleach at 12.
On the first two levels the strip has universal indicator colours, like the lab paper, and the test tube changes colour as the marker moves. On hard they are removed: you have to know the pH, and the colour appears on correction to make it stick.
Almost everyone thinks cola is mild and rainwater is neutral. The game puts them where they belong — cola nearly as acidic as lemon, rain at 5.6 because of CO₂ in the air — and explains why in one sentence.
"Up comes "Seawater". Many put it at 7 because it is water. On correction it shows at 8.1, slightly basic, with the explanation: it absorbs CO₂ from the atmosphere and its pH is falling, which is what ocean acidification means. A chemistry fact that is also a climate change fact."
Prefer to learn without screens? Try this analogue version:
Draw a strip from 0 to 14 and colour the three zones: red, green and purple.
Write ten household things on slips of paper and place them on the strip before checking anything.
Check against a list of real pH values and move the slips that were wrong.
If you have red cabbage, boil it: its purple water is an indicator that changes colour with vinegar and baking soda.
If you like pH Meter, these activities work similar skills:
The water from boiling red cabbage turns red with vinegar and green with baking soda. Same principle as the strip in the game, made with something from the fridge.
After playing, the multiple-choice exam revises the definition of pH, indicators and neutralisation, with an explanation for every answer.
Shampoos, shower gels and creams often say "neutral pH" or "pH 5.5". Finding one in the bathroom and placing it on the strip takes the scale out of the exercise book.
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