Big Manny GCSE Science Experiment: Titration
What is the purpose of titration?
The purpose of titration is to find out the concentration of a solution
Titration experiment using sodium hydroxide and hydrochloric acid
I’ve got a solution of sodium hydroxide here, and I don’t know what concentration of it is. I also have a solution of hydrochloric acid, and I know what concentration it is.
What I’m going to do first is measure out 25 milliliters of sodium hydroxide solution.
Now I’m using the glass pipette, remember you must make sure that we fill it up to the meniscus.
We have to ensure that the meniscus of the sodium hydroxide is level with the line on the glass pipette. Now we transfer the sodium hydroxide into a conical flask.
Now add some phenolphthalein indicator, now this is a pH indicator, and when it goes into a neutral or acidic solution it’s colorless, but when it’s an alkaline solution it turns pink.
So we’re going to add two to three drops to the sodium hydroxide, and it’s going to turn pink. Then we’ll just give it a little swish around like that.
Next we need to fill up our burette, so we’re going to fill up our burette and put the stand on the floor like this, and then we’re going to get our funnel and we’re going to put it into the top of the burette.
Before we begin the titration, we have to ensure that the tip of the burette is closed.
Now fill up the burette with some hydrochloric acid.
Right so when we’re filling up our burette we have to make sure that we will fill it, and we fill it to above zero line.
Now release the excess hydrochloric acid, and we’re going to get rid of the air bubbles that are formed at the bottom near the tap.
When you’re filling up the burette you have to ensure that you’re looking from eye level, this is to make sure that the meniscus of the hydrochloric acid is sitting on the line of zero of the burette.
Next put the burette back onto the table and then we can begin our titration.
Now we need to get our conical flask with the sodium hydroxide, and we put it underneath the burette, and then we slowly open our tap and we begin titrating the acid into the sodium hydroxide.
You have to make sure that as you’re titrating, you’re switching around the solution at the same time to ensure that it mixes properly.
Now as you’re titrating, every so often just close the tap and give it a little swish around and see if you see a color change.
As you get close to the end point of the titration, you have to add the acid drop by drop to make sure that you can observe when the colour changes.
Now as soon as the solution changes to colorless you must close the tap.
We can see that the solution is now colourless, this tells us that the sodium hydroxide has been neutralized by the hydraulic acid, now the volume of hydrochloric acid that we used, we can use that to calculate the concentration of the sodium hydroxide