Unit 2 : Practical ScientificProcedures and Techniques
Assignment A : Keeping up the standards
Introduction :
Titration is the process of determining the concentration of an acid or base by using a known
opposite solution.
Burette is used for an accurate mass of solutions, in this case Hydrochloric acid.
A graduated bulb pipette will be used for accurate measurements taken when transferring
solutions into containers.
Conical flask is used for the reaction to take place safely, and where Sodium Hydroxide will
be, mixed along with Phenolphthalein indicator.
There will be an additional beaker, this will be labelled as the waste beaker. In here you will
put the waste of Hydrochloric acid, Sodium Hydroxide and anything else that is used.
A white piece of paper will help you read the meniscus and the value it is at, this will be
handy when writing up your notes on your experiment.
A white tile will help you see the colour of the solution (pink) turn colourless better.
A clamp and stand will hold the burette and a funnel will help to pour the HCl into the burette
easier.
The application of titration in real life is that titration is used in laboratories in order to find out
the concentration of an unknown solution. Examples can vary from, laboratory medicine,
development of new pharmaceuticals, chemical food content, determining unknown
concentrations in liquids such as blood and ageing of food such as cheese and wine.
A neutralisation reaction is when an alkali and an acid react together in order to make salt
and water. The neutralisation reaction that takes place in the conical flask is between
Sodium Carbonate and HCl, this is an acid base reaction. This means that a double
displacement reaction takes place due to the results of Sodium Carbonate and Hydrochloric
acid being mixed together. The results would consist of Na₂CO₃, H₂O and CO₂. In this
reaction, water is a byproduct of the neutralisation reaction.
In the first stage the word equation would be Na₂CO₃(aq) + HCl(aq) →
NaHCO₃(aq) + NaCl(aq). This is due to the first indicator, phenolphthalein as it
can detect the change which is associated to NaHCO₃.
However in the second stage we add a different indicator, methyl orange as this
can detect the change which is associated with NaCl. The word equation would
be NaHCO₃(aq) + HCl(aq) → NaCl(aq) + CO₂(g) + H₂O(l).
, Unit 2 : Practical ScientificProcedures and Techniques
Assignment A : Keeping up the standards
The pH curve is a graph which describes the relationship between the concentration of the
H+ ions and the pH of a solution. These are mainly useful when understanding the structure
of acids and bases in solutions. When running acid into an alkali the pH will fall and become
steep, whereas when running alkali into the acid the pH will rise above the equivalence. The
graphs below are able to show an explanation of the pH curve.
Running acid through alkali.
Running alkali through acid.
The indicators used in titration are Phenolphthalein indicator and Methyl orange indicator.
When carrying out the experiment of NaHCO₃ you will be required to use the
phenolphthalein indicator as it is the most suitable and will respond to the pH change when
forming NaHCO₃.
When carrying out the experiment of NaCl, you will be required to use the methyl orange
indicator as it is the most suitable and will respond to the pH changes when forming NaCl.
Concentration is the amount of solute there is in a specific volume of the solvent.
And the equation is : concentration = number over moles divided by volume.
Concentration is measured in mol.dm-3.
Hazard Risk Prevention What to do incase of an
accident
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