Home Chemistry 13

At the March STEM group meeting last month we undertook an activity using red cabbage indicator.

I have been working on a follow up activity to examine what happens when eggshells are added to vinegar and how this changes the pH of the solution.

Equipment

• Test tube rack
• 2 x Test tubes
• 2x pipettes
• Goggles
• Lab coat (optional)
• Gloves (optional but ideal if you have some)
• COMMON SENSE

Chemicals

• White Vinegar
• Red Cabbage indicator
• Egg shells (crushed to small pieces)

Method

We will use one test tube as a 'control' to compare the results.

1. To the first test tube add 6 ml of Vinegar and 6 ml of Indicator.
2. Repeat for the second test tube.
3. Shake gently to mix if needed
4. To one of the test tubes only add some crushed egg shells, make sure they reach the liquid in the test tube
5. Shake gently if needed to help mix

If you now wait a while you will notice a colour change in the second tube, compared to the first tube.

What is happening

The calcium carbonate (alkali) in the eggshell reacts with the vinegar (acid) and neutralises the acid. You should be able to see bubbles.

Results

The control is on the left hand side, results are on the right. You can see a clear difference in colour.

Further reading

• Chemistry of Egg shells
• Red Cabbage pH indicator

We can have a go at this at the Saturday STEM group meeting to confirm the results and may be try this out with different acids.

Maybe discuss further and share results on the Science Forums – Experiments section

Tags

#Chemistry,#HomeChemistry,#HomeChemistry13,

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