Acids, alkalis and neutralisation
Acids and alkalis are opposites that cancel each other out. Neutralisation explains indigestion remedies, soil treatment and the safe handling of chemical spills.
Part of your national curriculum
- Chemistry: chemical reactions: Understand reactions of acids with alkalis to produce a salt plus water, and use the pH scale for measuring acidity
Lesson overview
What you'll learn in this lesson
Understand reactions of acids with alkalis to produce a salt plus water, and use the pH scale for measuring acidity
Key learning points
- • The pH scale
- • Neutralisation
- • Acids with metals and carbonates
- • Everyday neutralisation
This lesson at a glance
- 30 minutes
- 21 parts to scroll through
- 4 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 21
Visual introductionPicture this
Acids, alkalis and neutralisation
Acids and alkalis are opposites that cancel each other out. Neutralisation explains indigestion remedies, soil treatment and the safe handling of chemical spills.
In a nutshell
Understand reactions of acids with alkalis to produce a salt plus water, and use the pH scale for measuring acidity
Learning cycle
Part 2 of 21
Learning cycle 1 of 2
Part 1 · The pH scale
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 3 of 21
Learn
The pH scale
pH runs from 0 to 14: below 7 is acidic, 7 is neutral and above 7 is alkaline. Universal indicator gives an approximate colour-coded value, while a pH probe gives a precise numerical reading, which matters when a question asks for accurate data.
Reset break
Part 4 of 21
Pause
That's sitting 1 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Explore the idea
Part 5 of 21
Learn
Neutralisation
Acid + alkali → salt + water. Hydrochloric acid with sodium hydroxide gives sodium chloride and water. The name of the salt comes from the metal in the alkali and the acid used: hydrochloric acid makes chlorides, sulfuric acid makes sulfates and nitric acid makes nitrates.
Quick check
Part 6 of 21
Quick check
Part 7 of 21
Reset break
Part 8 of 21
Pause
That's sitting 2 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Learning cycle
Part 9 of 21
Learning cycle 2 of 2
Part 2 · Acids with metals and carbonates
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 21
Learn
Acids with metals and carbonates
Acid + metal → salt + hydrogen, tested by a squeaky pop with a lit splint. Acid + metal carbonate → salt + water + carbon dioxide, tested by turning limewater cloudy. Recognising the general pattern lets you predict products for reactions you have never seen.
Explore the idea
Part 11 of 21
Learn
Everyday neutralisation
Indigestion remedies contain a mild alkali that neutralises excess stomach acid. Farmers add lime to acidic soil so crops can absorb nutrients. In both cases the aim is to reach roughly neutral, not to overshoot into strong alkalinity, which would cause its own problems.
Reset break
Part 12 of 21
Pause
That's sitting 3 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Quick check
Part 13 of 21
Quick check
Part 14 of 21
Explore the idea
Part 15 of 21
Worked example
Worked answer: name the salt formed when sulfuric acid reacts with sodium hydroxide, and write the word equation (3 marks)
The metal in the alkali is sodium and the acid is sulfuric, so the salt is sodium sulfate (1). The general pattern is acid + alkali → salt + water (1). The word equation is: sulfuric acid + sodium hydroxide → sodium sulfate + water (1). Answering 'sodium chloride' confuses the acid used.
Reset break
Part 16 of 21
Pause
That's sitting 4 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Challenge round
Part 17 of 21
Game · Sort it
Which of these are true?
Drag each card into the right column. Tap a card first if dragging is fiddly.
True
Not true
Challenge round
Part 18 of 21
Game · Fill the gaps
Finish the sentences
Choose the word that belongs in each gap.
Recognising the general pattern lets you predict products for ____ you have never seen.
Challenge round
Part 19 of 21
Game · Recall cards
What pH value is exactly neutral?
Card 1 of 4
Mastery quiz
Part 20 of 21
Marked quiz
End of lesson quiz: Acids, alkalis and neutralisation
4 questions, marked with the reasoning shown. No timer.
1. What pH value is exactly neutral?
2. What are the products of a neutralisation reaction?
3. What salt is formed from sulfuric acid and sodium hydroxide?
4. A pH of 3 indicates
Lesson round-up
Part 21 of 21
Lesson round-up
Ready when you are
Quiz score
Not sat
Games
Not played
Points this lesson
0
Best run
0 in a row
Luna: 0 out of 4 on the practice checks. Only if you feel up to it — one more?
Ask LunaPart 1 of 21 · Watch & discover
How this is going
- Not looked at yet
Understand reactions of acids with alkalis to produce a salt plus water, and use the pH scale for measuring acidity