Sunday, 9 December 2012

Acid and Alkali experiments for children

A few months ago,we investigated acid and alkalis...

We began with this fun experiment, 
mixing acid and alkali together and watching the result!

Pour vinegar into a container, add food colouring and washing-up liquid.
Add a heaped teaspoon of bicarbonate of soda.
And enjoy the fun!

When you mix vinegar and bicarbonate of soda,
carbon dioxide is released as a by-product of the reaction.
Bicarbonate of soda was originally developed to help bread and cakes rise.
A similar reaction occurs in cake mix. The carbon dioxide bubbles make the mixture expand and rise.

I introduced the chemical reaction to the girls. 
We looked at the state symbols and how the equation balances.

Then we moved onto the 'Dancing Raisin' experiment.

We put water, vinegar and bicarbonate of soda into a glass and added raisins.
We also tried a control experiment, where we placed the raisins in water 
to see if they would 'dance'.The girls wrote up the experiment:

Raisins are denser than the liquid, so initially they sink to the bottom of the glass. The reaction releases carbon dioxide bubbles. When these bubbles stick to the rough surface of a raisin, the raisin is lifted because of the increase in buoyancy. When the raisin reaches the surface, the bubbles pop, and the carbon dioxide gas escapes into the air. This causes the raisin to lose buoyancy and sink. This rising and sinking of the raisins continues until most of the carbon dioxide has escaped, and the reaction has finished. Eventually, with time the raisin gets soggy and becomes too heavy to rise to the surface.

Cabbage Indicator paper.
 We made indicator paper to check if substances were acid, alkali or neutral.

Chop up half a red cabbage

Put it in a saucepan and cover it with water.
Don't add too much.
Boil the cabbage and let it cool.
Sieve and collect the drained liquid.
We used coffee filter papers. Dipped them in the liquid and leave them to dry.
We added too much water to the cabbage when we boiled it, so the indicator papers were too pail. Although they did still work.

We tested household liquids with the indicator strips.
Red indicates acid, Green alkai
and Neutral stays the same.

... our results.

 Other experiments

Paint a picture with lemon juice.

Leave the paper to dry. 
Then rub over with a wax crayon and a picture appears!

The lemon juice alters the surface of the paper. 
Rubbing a crayon over it allows you to see this. 

Soak two pieces of paper towel in milk and leave them to dry.

Rub bicarbonate of soda onto one of the pieces.

Sniff both pieces!
Imogen hates this photo, so it may get removed!
The bicarbonate of soda is able to neutralize the smell of sour milk.

We all had great fun doing these experiments
and learnt quite a bit of chemistry in the process!


  1. My mom and I loved this post. What fun! I'm definitely going to have to try some of these experiments myself!

    P.S. My mom would like to know if you have tried the lemon juice on paper and added heat from a light bulb. We used to send each other "secret" messages that way as kids.

  2. This is awesome! I'm going to print it out so I can entertain my grandchildren sometime when they stay over!

    abcw team

  3. Such a fun project.

    Catching up with ABC entries.

    Rose, ABC Wednesday Team

  4. Great experiments. I used the first one with some children as a demo for a volcano.

  5. AMAZING post which both ADULTS and children can enjoy! Kate,ABC Team

  6. I love the different experiments you did. I've been meaning to make indicator paper for a while and haven't yet.

    Thanks for linking up to Science Sunday!

  7. Love your homemade litmus paper. Pinning for later.

  8. Thanks for linking to HammockTracks. Your children have such intense looks as they work on their projects. You obviously have them interested.

  9. I have featured you on HammockTracks and I look forward to seeing what you learn in April.



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