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The Acid test

  NO HEATING INVOLVED - EVERYDAY ACIDS AND ALKALIS.

EYE PROTECTION ADVISED
You will need:
  • Some cabbage juice indicator
  • A 30cm ruler
  • a pencil
  • 3 x 100ml beakers, yoghurt pots or similar
  • A 1p coin
  • dropping pipette or syringe with measurements
  • some kind of measuring cup /beaker (up to 100ml)
  • 200ml boiled ( or distilled) water **
  • Bicarbonate of soda (aka sodium bicarbonate)
  • 20ml Vinegar ( white is best)
  • If no vinegar the juice of a lemon will do

** Note to PARENTS:

The boiled water should be prepared in advance with adult supervision. Boil about 300ml of tap water - for 5 - 10 minutes. You should see white solid ( limescale ) appear after a while. When you think no more white solid is forming - let the water cool before filtering/decanting . Allow to cool for later use.



 This is what we did!

Making sodium bicarbonate solution

  1. Use your ruler as a balance shown in the pictures to measure out a mass of sodium bicarbonate solid equal to the mass of a 1p piece . This is actually 3.55g. 
  2. Add the sodium bicarbonate to 80 ml (boiled) water in a measuring beaker/jug.
  3. Stir until it all dissolves.

This procedure is our attempt to compare some acids by measuring how much sodium hydrogen carbonate solution is needed to neutralise the acid.  

Diluting the vinegar 

  1. Dilute your vinegar by adding 10ml of vinegar to 90 ml (boiled) water.
  2. Add 10ml of this solution to a clean beaker 
  3. Add enough cabbage juice extract to give a strong colour.
  4. Add a similar amount of cabbage juice to another clean beaker with just (boiled) water in it.

Neutralising the acid

  • Use a pipette or syringe to add small volumes ( note how much each time) of the sodium hydrogen carbonate solution to the diluted vinegar.
  • As you add it, the colour of the cabbage juice will change from red to a blue colour.
  • Your task is to find the volume of sodium hydrogen carbonate solution needed to change the colour to a blue colour ( the same as the colour when in water).

 This is what we found out

Researcher's initial Name of acid used Volume of sodium hydrogen carbonate solution needed /ml
J Apple cider vinegar 45
MCyder Vinegar40
O
JLemon Juice60
M
O

 The tekkie bit..

Sodium hydrogen carbonate. How many elements are in it?

In this experiment we made a solution of sodium bicarbonate ( sodium hydrogen carbonate) . 

Sodium hydrogen carbonate has the following chemical formula: 



The formula for ethanoic acid

This solution was then used to neutralise the acid in a measured volume of vinegar ( acetic or ethanoic acid). Cabbage juice indicator was used to tell when the acid had been neutralised. 

 This experiment involved measuring the volume of one solution needed to completely react with another solution.  This process of measuring volumes of reacting solutions is known as titration .

2.28 Acids, alkalis and titrations

The pH of everyday substances and their pH values can be found using universal indicator  2.28 Activity 1. The Acid test Acids and alk...
https://www.mychem.co.uk/index.php/igcse-chemistry/inorganic-chemistry/acids-alkalis-and-titrations
 

Comments 4

Guest - Helen Rashbrook on Thursday, 16 April 2020 07:14

Hi Dave I am getting ready

Hi Dave I am getting ready
David Fowkes on Thursday, 16 April 2020 08:43

Excellent. See you at 1500

Excellent. See you at 1500
magnus miller on Thursday, 16 April 2020 11:24

All of my things are ready.

All of my things are ready.
magnus miller on Thursday, 16 April 2020 14:56

I added 72ml of vinegar diluted to make it a light reddish colour. Then I added 40ml of sodium hydrogen bicarbonate and it looked the same as it did before.

I added 72ml of vinegar diluted to make it a light reddish colour. Then I added 40ml of sodium hydrogen bicarbonate and it looked the same as it did before.
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Sunday, 09 August 2020