neutralisation (titration)

Neutralisation reactions occur when an acid reacts with an alkali. A titration is a practical technique that allows us to accurately measure how much acid is required to neutralise an alkali (or vice versa). In this practical, you will perform a titration to find the volume of sulfuric acid that is required to neutralise 25 cm3 of sodium hydroxide solution. You will then use the volume of sulfuric acid required to calculate the concentration of the sulfuric acid.

aim

determine the reacting volume of solutions of a strong acid and a strong alkali by titration

equipment

• sodium hydroxide solution (with known concentration)

• sulphuric acid solution (unknown concentration)

• burette

• clamp and stand

• funnel

• bulb pipette & safety fillers

• indicator

setup

measure out an exact volume of sodium hydroxide solution with a bulb pipette

attach safety fillers to top of pipette and place it in solution - suck up solution into pipette until the bottom of the meniscus reaches the 25cm³ line

drop solution into conical flask

pour sulphuric acid into burette using a funnel until the bottom of the meniscus reaches the 0 line

place conical flask underneath the burette

add some pH indicator e.g. methyl orange into acid (where it appears yellow)

steps

1. first, do a rough titration to know around how much acid needs to be added

2. open the tap and swirl the flask

3. when colour change stops occurring stop titration

4. repeat, use rough titration to estimate when to add smaller volumes of acid for accuracy

5. when colour change occurs, record final volume of acid in burette

6. repeat until achieve concurrent results (results in 0.1cm³) and calculate the mean

7. can then calculate concentration of unknown solution