To Preparation and Standardization of 0.1 N HCl utilizing sodium carbonate (also comprehended as washing soda, soda ash, and soda crystals) as the primary standard (Acid-base titration).
Prerequisites for preparation and standardization of 0.1 N HCL:
Glasswares: Burette, stand for burette, a conical flask, volumetric pipette to makeup volume, beaker, volumetric flask, funnel, glass rod, washed bottle, etc.
Chemicals: Concentrated HCl, sodium carbonate (Na2CO3), methyl orange indicator, etc.
Principle:
To titrate the hydrochloric acid solution a methyl orange indicator can be used against the sodium carbonate solution. When titrating a slightly acidic solution with a weak base, the endpoint is also slightly acidic. When a weak acid is titrated with a strong base, the solution is somewhat alkaline because the salt produced is partially hydrolyzed.
The reaction of sodium carbonate with hydrochoric acid is following:
Na2CO3(aq) + 2HCl(aq) → 2NaCl(aq) + CO2(g) + H2O(l)
CO32-(aq) + 2H+(aq) → CO2(g) + H2O(l)
In an acid-base titration process, the portion of acid becomes chemically equivalent to the quantity of base present. The solution becomes neutral when a strong acid and a strong base are titrated concurrently.
How to prepare 0.1 N HCl:
To prepare 0.1 N HCL, Dilute 8.50 ml of HCL with distilled water to make up the volume to 1000 ml.
How to prepare 0.1M Na2CO3 solution:
To prepare 0.1M Na2CO3 solution, Take 1.06 gm of sodium carbonate and well mixed in 50 ml of distilled water in a given volumetric flask, and properly mix it to get dissolved and finally make it up to 100 ml volume.
Titration procedure:
- Make sure all the glassware should be cleaned properly before use as per standard laboratory procedure.
- Rinse the burette with distilled water before its use, also rinse with a small portion of titrant solution to avoid contamination of the solution.
- To remove the air bubble from the burette, Take the solution of titrant in a clean and dry beaker then fill the burette using the funnel, and finally set the reading to zero.
- Now by using a pipette, transfer the 5 ml of prepared solution of sodium carbonate (Na2CO3) and pour it into a conical flask. now add one or two drops of methyl orange indicator drop by drop.
- Now Start the titration by addition of Hydrochloric acid (HCL) drop by drop followed by stirring continuously, until the solution turns pale pink.
- Now take the solution and Boil it until the color turns yellow again, then cool and titrate similarly until a faint pink color is no longer impacted by boiling.
- Repeat the titration process three times to get a better result and same time take the reading from the pipette. Calculate the mean to find out the normality of the HCL solution.
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Calculations for 0.1N HCL:
N x V = wt. / eq. wt. x 1000
Where,
N denoted for normality of HCl to be calculated
V denoted the volume of HCl used
Wt. is denoted for the weight of Na2CO3
eq. wt is denoted for equivalent Weight of Na2CO3
Result:
The prepared HCl solution was discovered to have the following strength:_____N.
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