Hydrochloric Acid + Sodium Hydroxide Sodium Chloride + Water
Or
HCl + NaOH NaCl + H2O
Method
In this section the following techniques would be used to complete the experiment to a satisfactory standard to provide the results. However there are many safety points that must be addressed, these are:
Keep your hair tied back to prevent the acid from burning your hair.
Wear safety goggles to prevent splashes from each of the solutions getting in your eyes.
Wear suitable clothing that will not be able to touch the solutions and this will be able to save the clothing and your skin because of the acid corroding the skin. A good example of clothing that could be used in this experiment is a lab coat.
The experiment was constructed using the following equipment:
1 x Bunsen burner
1 x Tripod
1 x Wire gauze
1 x Burette
2 x Conical flasks
1 x heatproof mat
3 x measuring glasses
1 x crucible
1 x measuring tube
1 x small funnel
1 x pH indicator
1 x solution of Hydrochloric Acid
1 x 25cm3 of sodium hydroxide
The following instructions are to successfully complete the experiment:
Begin by preparing your burette, your buret should be conditioned and filled with titrant solution. You should check for air bubbles and leaks, before proceeding with the titration.
Take an initial volume reading and record it in your notebook. Before beginning a titration, you should always calculate the expected endpoint volume.
Prepare the solution to be analysed by placing it in a clean Erlenmeyer flask or beaker
Use the buret to deliver a stream of titrant to within a couple of cm3 of your expected endpoint. You will see the indicator change colour when the titrant hits the solution in the flask, but the colour change disappears upon stirring.
Approach the endpoint more slowly and watch the colour of your flask carefully. Use a wash bottle to rinse the sides of the flask and the tip of the buret; to be sure all titrant is mixed in the flask.
As you approach the endpoint, you may need to add a partial drop of titrant. You can do this with a rapid spin of a Teflon stopcock or by partially opening the stopcock and rinsing the partial drop into the flask with a wash bottle.
Make sure you know what the endpoint should look like. If you think you might have reached the endpoint, you can record the volume reading and add another partial drop. Sometimes it is easier to tell when you have gone past the endpoint.
When you have reached the endpoint, read the final volume in the buret and record it in your notebook.
Subtract the initial volume to determine the amount of titrant delivered. Use this, the concentration of the titrant, and the stoichiometry of the titration reaction to calculate the number of moles of reactant in your analytic solution.
Then repeat the experiment about 3 times to give a more accurate result.
Then when the average has been found. First calculate the weight of the crucible then calculate the weight of the crucible with the solution.
Then boil out the water of the solution then the sodium chloride should be left.
Then wait for the crucible to cool down.
Then weigh the crucible to find out how much salt there is.
Subtract the first weight of the crucible with the overall weight of the crucible to leave the total weight of the sodium chloride.
Results
The results for the experiment are as follows:
The reaction between the hydrochloric acid and the sodium hydroxide has resulted in water plus sodium chloride (This is found as mainly common table salt).
First weight of crucible 46.29
The time taken for the two substances to become neutral has been recorded three times with an average taken to give a more accurate result.
These results are as follows:
Measurement of hydrochloric acid to turn the sodium hydroxide neutral
1st experiment 12.3 ml3
2nd experiment 11.8 ml3
3rd experiment 11.4 ml3
Total 35.5 ml3
Average 11.83 ml3
(Total amount of experiments dived by how many experiments preformed)
Weight of crucible plus solution = 87.07 ml3
Weight of crucible plus salt = 46.59g
Weight of salt = 0.30g
The titration of the solution can be recorded into what strength of mol can be used to successfully neutralise the solution. This can be worked out into the following using algebraic terms.
N = amount of substance
C = concentration of solution
V = volume of solution
This is a two-step process looking at the use of both solutions
N (NaOH) = 2 x 25 = 0.05mol
100
N (HCl) = 2 x 11.83 = 0.24mol
100
So working down to a simple expression it would turn out to be that 25cm3 of NaOH contains 0.05mol of NaOH. While 1 cm3 contains 0.05mol divided by 25 = 0.002mol of NaOH.
Overall if I wanted to find out how much molar there is in 1 dm –3 (This basically means 1 litre) you would calculate 0.05 * 1000 = 2mol
25
Conclusion
Overall the experiment could have been improved by including the use of a thermometer to measure the reaction between the two solutions.
The experiment went well and the stronger calculations were easy to work out when the right results were shown.
Overall the experimental hypothesis was proven to be successful without any problems to cause the results to be contaminated. The explanation of the titrant I believe has been fully explained to show people how to do this experiment without any scientific knowledge and allow them to get similar results to the ones found in the results page.
However the experiment could of gone a lot better if the temperate of the room was a bit lower to rule out any tampering of the experiment. I am pleased with the overall results and I would like to do the experiment again with the additional equipment to help get use to the scientific area and atmosphere once again.
Bibliography
Science for dummies 1997 – Auteur Cole
Class notes – J. Long 2003
- the information about the pH scale and relevancey
