Using the results from the calculations, the first titration will use 1g of Sodium Hydroxide diluted in 250ml of distilled water resulting in the concentration being 0.1mol/dm3. The second titration will use 3g of Sodium Hydroxide Sulphate diluted in 250ml of distilled water also resulting in the concentration being 0.1mol/dm3.
Aim
The aim of this investigation is to find the unknown concentration of two solutions by titration. The first being Hydrochloric Acid (HCl) and the second being Sodium Hydroxide (NaOH). The investigation will also determine the volume need to neutralise the solution of either the acid or alkali.
Method
In this experiment the main equipment needed will be; a burette, pipette, pipette filler (25cm3), clamp stand and a conical flask.
The first titration uses Sodium Hydroxide with concentration 0.1mol/dm3 and hydrochloric acid of unknown concentration. To carry out this experiment, a 25cm3 pipette is filled up with sodium hydroxide using the pipette filler. Next the burette is filled up with hydrochloric acid solution, to the 0.0cm3 and successfully secured to the clamp stand. After this 4 drops of acid indicator should be added to the Sodium Hydroxide solution in the flask causing the transparent solution to turn a pinkish colour. The conical flask should then be placed directly under the burette enabling the hydrochloric acid solution to fall into the conical flask from the burette. Once everything is in place the tap on the burette should be opened allowing the hydrochloric acid to fall into the conical flask and mixing with the Sodium hydroxide. To be sure that the two solution are mixing together the conical flask should be rotated around to be sure of even mix. When the pinkish tone starts to become colourless the tap on the burette should be closed and opened repeatedly to allow drops of Hydrochloric acid to join the Sodium Hydroxide. Doing this decreases the chance of missing the neutralisation stage and also increases the accuracy of the reading. When the solution in the conical flask becomes colourless, the tap should be closed and a reading from the burette taken and recorded in a table. This experiment should be completed 10 times, recording a result each time.
The 2nd titration uses Sodium Hydrogen Sulphate with concentration of 0.1mol/dm3 and sodium hydroxide of unknown concentration. A 25cm3 pipette is filled using Sodium Hydrogen Sulphate and transferred to a conical flask where 4 drops of Methyl orange should be added to the Sodium Hydrogen Sulphate turning the solution red. The conical flask should be placed directly under the burette and the burette should be filled to 0.0cm3 with Sodium Hydroxide. Next the tap on the burette should be open enabling the Sodium Hydroxide to mix with the Sodium Hydrogen Sulphate. To ensure both mixture are mixing together; the conical flask should be rotated. When the solution in the conical flask starts to become colourless the tap on the burette should be open and closed repeatedly allowing small amounts of solution out until the solution in the conical flask is colourless. Once colourless the results should be recorded in a table and the experiment must be repeated until 10 results have been recorded.
Diagram to show the set-up of the titration used in this report
Image sourced from- http://en.wikipedia.org/wiki/Retort_stand
Results
1st Titration
2nd Titration
Discussion
1st Titration
By looking at the result it could be argued that the first result (21.8ml) could be an anomaly. The anomalous result could have occurred in many ways; a human error in the reading, error in the equipment. However, reviewing the titration, the conical flask and burette where not cleaned with the acid they were holding beforehand. This could mean that chemicals present in the burette or conical flask may have caused the Sodium Hydroxide using a smaller amount of Hydrochloric acid.
During the titration, measuring accuracy of the equipment have to be taken into account. The pipette has an accuracy of ±0.06cm3 meaning the accuracy of the equipment is pretty good. Next the burette has an accuracy of ±0.05cm3. The accuracy of each equipment needs to be taken into account when recording results.
From the results recorded from the first titration, it is a good set of results because research shows that it takes roughly 24ml of Hydrochloric acid to neutralise 25cm3 of Sodium Hydroxide. Therefore the results are reliable.
Sodium and Chlorine is the main ionic bond for the first titration. Sodium chloride is created when chlorine gains one atom from sodium when they both combine. Although they are both extremely reactive they create a non-reactive substance when they combine.
2nd Titration
My results from the second titration are different to the first titration, there are no clear anomalies that have been recorded in the table. This shows that the titration was quite successful as all the results recorded are similar.
Once again the accuracy of the equipment had to be taken into account. The Pipette has an accuracy of ±0.06ml meaning the accuracy of the equipment is pretty good. Next the burette has an accuracy of ±0.05cm3. The accuracy of each equipment needs to be taken into account when recording results.
In the second titration sodium displaces the hydrogen because it is a group 1 metal.
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HCL + NaOH NaCl + H2O
1 mole of HCL reacts with 1 mole of NaOH; 1:1 ratio.
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NaHSO4 + NaOH Na2 SO4 + H2O
Concentration= moles/volume.
0.025/0.0233= 1.07mol/dm3
Using the results it shows that the concentration of the hydrochloric acid used in the titration is 1.07mol/dm3.
In the second titration the unknown concentration of Sodium Hydroxide can also be worked out. The average amount of Sodium Hydroxide to neutralise 25ml Sodium Hydrogen Sulphate is 20.5cm3. Using the same equation from above, the concentration of Sodium Hydroxide can be calculated.
0.025/0.0205= 1.22mol/dm3
This result shows that the concentration of Sodium Hydroxide in the second titration was 1.22mol/dm3.
Conclusion
The aim of the 2 titrations was too find out how much concentration was in theHydrochloric Acid and Sodium Hydroxide. Another aim of the titration were to find out the amount of Hydrochloric acid took to neutralise 25cm3 of Sodium Hydroxide and the amount of Sodium Hydroxide took to neutralise 25cm3 of Sodium Hydrogen Sulphate.
In the first Titration we can use the results to find out the concentration of Hydrochloric Acid. On average it took 23.29ml of Hydrochloric acid to neutralise 25cm3 Sodium Hydroxide. To find the concentration of the Hydrochloric acid, this equation must be used.
There are some similarities between the experimental and theoretical results of both titrations. The only anomalous result in the first experiment was due to the equipment not being cleaned before the experiment. Apart from that the experiment went well and was reliable and accurate. From the experiment, the results show that it takes 23.23cm3 of Hydrochloric Acid to neutralise 25ml of sodium hydroxide and 20.5cm3 Sodium hydroxide to neutralise 25ml Sodium Hydrogen Sulphate. The experiment is easy to set up and the method is easy to follow.
Titration in industry is very important. An example of titration in industry is when the pH of juice is tested. They use titration on the juice to see if it meets the required standards of the product, also titration allows science industries to test if a product contains how many moles it actually says. Titration is only used on the prototype and then is used on every batch of product made to make sure it consistently meets the standards. Titration enables us to find the known pH and concentration of a solution.
by
joshtinsley96hotmailcouk (student)
