Finding Out How Much Acid there is in a solution.

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By Osman Khan

Lee 12



Conical Flask

Clamp Stand

2 x 100cm3 Beakers

Distilled Water

Sulphuric Acid

Methyl Orange Indicator

Sodium Carbonate

Glass Rod

Filter Funnel

250cm3 Volumetric Flask

Weighing Scales


Pipette Filler

Quantities of Chemicals

  • 2.65g sodium carbonate
  • 3 drops of methyl orange indicator
  • Add as much sulphuric acid as is needed to neutralise the sodium carbonate/water solution


  1. Weigh out 2.65g of sodium carbonate and place this in a 100cm3 beaker. Rinse out the pot in which the sodium carbonate was weighed in using distilled water and pour this into the beaker also (this ensures all of the solid will go in the beaker and reduce experimental inaccuracy).
  2. Pour distilled water into the beaker until there is 50cm3 of water into the beaker and then, using a glass rod, stir the contents until the solid has fully dissolved.
  3. Using a filter funnel transfer the solution from the beaker into a 250cm3 volumetric flask, ensuring none is spilt. Rinse the beaker using distilled water and pour this into the volumetric flask also. After this has been done rinse the funnel also to ensure all the solution entered the flask.
  4. Add water to the volumetric flask until the solution is approximately 1cm3 away from the graduation mark. Once this has been done make the level up to this mark by using a pipette, ensuring the meniscus is just touching the graduation mark. Stopper then flask and invert it a few times to ensure the solution is properly mixed
  5. Using a pipette and pipette filler draw 25cm3 of the solution from the volumetric flask and transfer this to a conical flask. Once this is done add 3 drops of methyl orange indicator to the conical flask also.
  6. Clean the burette by running some sulphuric acid through it (including the jet) and then, using a clean, dry 100cm3 beaker and a funnel, fill the burette with sulphuric acid.
  7. Record the volume of the initial burette reading to the nearest 0.05cm3 and then add the sulphuric acid, in small volumes, to the conical flask containing sodium carbonate. Each time sulphuric acid is added to the conical flask, swirl the flask to ensure the contents mix properly. Do this until you have identified that the pH level of the solution in the conical flask is neutral. Record this volume to work out the volume of acid which has been added to the conical flask.
  8. This first titration is a rough one, designed to give an idea of the approximate amount of acid and alkali required for the solution to become neutral. Do several more titrations until the readings are within 0.1cm3 of each other
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Justification of Quantities of Materials being used

        Due to the fact that the concentration of the sulphuric acid is between 0.05 and 0.15 moldm-3 I will make the sodium carbonate 0.1 moldm-3 for convenience. Above I have stated that I will use 2.65g of sodium carbonate. I have derived this from the following calculations:

Molecular Mass Na2CO3         = (23 x 2) + 12 + (16 x 3)

                                = 106

Therefore 1 mole of Na2CO3 is 106g

I require 0.1 mole so        = 106 / 10

                        = 10.6g

Therefore 10.6g will be dissolved in 0.25dm3 so there ...

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