Making a Standard Solution of Sodium Carbonate
Outline of procedures: to prepare a standard solution of sodium carbonate and carry out a series of titrations to determine the concentration of hydrochloric acid.
Standard solution experiment
Finding the concentration of a chemical
A solution of known concentration is called a standard solution.
Hazardous substances being made or used.
Nature of hazards
Quantities being used
Control measures and precautions
Wear lab coat and goggles.
Any non-chemical hazards and precautions to be taken
Any spills to be wiped immediately
Disposal of residues.
Done by Technician
* weighing bottle
* glass rod
* wash bottle
* filter funnel
* volumetric flask
* teat pipette
* conical flask
To prepare a standard solution first I will calculate the mass of solute needed. Then I will carefully weigh out the mass of solute, dissolve it into the water and transfer the solution into a volumetric flask. This is a flask of known volume. When the level of liquid in the flask reaches the graduation mark on the neck of the flask I will know the volume of the liquid in the flask. I will then add distilled water to top off the solution to the graduation mark.
A standard solution can only be made from a pure solid which is stable in air therefore I will have to make a solution of sodium hydroxide and then find its concentration. I will do this by titrating it against an acid of known concentration.
Also you cant make a standard solution of hydrochloric acid as when you open the bottle hydrogen chloride escapes into the air so I will have to find the concentration of HCL by titrating it against a standard alkali.
The steps I will take to complete this experiment are as follows.
To make 250cm3 of 1.00mol/l solution of sodium carbonate I will use the following measurements:
Mass of 1.00 mol of Na2CO3 = 106g
Mass of Na2CO3 needed to make 1.00 l of a 0.100mol/l solution = 10.6g
Mass of Na2CO3 needed to make 250cm3 of a 0.100mol/l solution = 2065g
Mass of weighing bottle = 9.277g
Calculated mass of anhydrous sodium carbonate = 2.65g
Mass of weighing bottle + solid = 11.93 g
(i) With a clean dry spatula I added anhydrous sodium carbonate to the weighing bottle using a top pan balance until the weighing bottle and contents reached the combined mass that I had calculated.
(ii) I then poured 100cm3 of distilled water into a clean beaker and carefully tipped the sodium carbonate into the beaker.
(iii) I then used a wash bottle to wash out all the solids out of the weighing bottle and then stirred the contents of the beaker using a clean stirring rod until all the solids had dissolved.
(iv) I then poured the contents of the beaker into the volumetric flask using a filter funnel and pouring it down the glass rod to avoid splashing.
(v) I then used a wash bottle to wash out any remaining solution out of the beaker and poured it into the volumetric flask. I then used a teat pipette to add distilled water to make the solution reach the graduation mark before putting the stopper on it and shaking it gently.
(i) I poured the solution into a conical flask and added three drops of indicator.
(ii) I then measured 25cm3 of hydrochloric acid using a pipette and then slowly poured it into the conical flask which already contained the sodium carbonate solution I had made earlier and indicator.
(iii) I stopped when the solution turned pink and measured the level of HCL left in the pipette.
(iv) Then repeated these steps three times to get a fair result
Final burette reading
Initial burette reading
Na2CO3 + 2HCL –> NaCl + H2O + CO2
Mols of Na2Co3 = 0.0025
Ratio = 1:2
Mols of HCL = 0.005
Concentration of HCL = 0.238mols/dm3
Standard solution of sodium carbonate: Conclusion
In this experiment, I was able to find out the concentration of a chemical through many experiments.
This experiment was carried out under conditions similar to those in an industrial process but there were a couple of differences which include the number of chemicals available to us which hampered our chances of experimenting with different types of chemicals. I think this experiment was a success because I achieved my goal and learned a lot from it.