ACIDS, ALKALIS AND TITRATIONS - CHEMISTRY

What colour does litmus paper turn according to pH?

0-6 red, 7 purple, 8-14 blue

What colour does phenolphthalein turn in acidic/alkaline solution

Acidic - colourless

Alkaline - pink

What colour does methyl orange change in acidic/alkaline solutions

Acidic - red

Alkaline - yellow

How do you use universal indicator?

Add the indicator to the solution and compare the colour formed to a chart

What are acids?

Acids are proton donors and a source of H+ ions. They have a pH of less than 7

What are alkalis

Alkalis are soluble bases. An alkali is a source of hydroxide ions and has a pH greater than 7.

What are acid-base reactions?

Acid-base reactions are neutralisation reactions. The acid donates protons which are accepted by the base

What do titrations find?

Exactly how much acid is needed to neutralise a quantity of alkali (or vice versa)

How do you conduct a titration?

1. Use a Pipette and a Pipette filler, add some alkali to a conical flask, along with 2/3 drops of indicator

2. Fill a burette with the acid. Do this below eye level

3. Using the burette, add the acid to the alkali bit by bit

4. Regularly swirl the conical flask

5. The indicator changes colour when all the alkali has been neutralised

6. Record the volume of acid used to neutralise the alkali.

7. Repeat this process to make sure your results are reliable