Big Manny GCSE Science Experiment: Neutralisation

Neutralisation experiment with vinegar, sodium bicarbonate and indicator paper

What I have here is some vinegar, now vinegar is an acid, and all acids have a pH below seven.

The pH of vinegar is between two to three. We can neutralise this vinegar by reacting it with a base, and the base that we’re going to use is sodium bicarbonate.

Now we can test the pH of the vinegar using some indicator paper. We can see that the indicator paper has turned orange, now this indicates to us that the vinegar is acidic.

If you look at the pH chart, we can see that the vinegar has a pH of three. Now we can also test the pH of the vinegar by using some universal indicator. We will put a few drops and see what color it turns. What we can see is that the indicator has turned the solution red, and that gives us a pH of around two to three as well.

Now we will neutralise the vinegar by using some sodium bicarbonate. I’m going to get a spatula and I’m going to add a little bit to the vinegar, and then stir it in. We can see some fizzing taking place there.

Right so we can see that as I’m adding the sodium bicarbonate to the vinegar, the solution is changing color from red to yellow, and that’s because the pH is increasing and the solution is becoming neutralised, so I’m going to add some more until we get green.

The solution is starting to turn green, and the reason why is because it’s being neutralized. Now the products of a neutralization reaction, are always salt plus water, now in this case the salt that we produce is sodium acetate plus water plus carbon dioxide gas as well.

The vinegar, also known as ascetic acid, has been neutralized by the sodium bicarbonate and we’re going to test the pH by using some pH indicator paper. We can see that the pH indicator paper has now turned green, which is telling us that the solution has been neutralized and has a pH of seven.

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