How Much Titration Does the Sodium Hydroxide React With Hydrochloric Acid

The Purpose of this experiment is to find out how much NaOH is needed to neutralize the amount of HCl. This experiment will be done by slowly adding the hydrochloric acid into the flask of HCl and phenolphthalein. The result is known through the appearance of pale pink while neutralizing and recorded the volume of NaOH to find out titration.

Background

Analyte is the unknown concentration substance which is find out through titration technique, that is used to slowly add known concentration solution, reaches neutralization.

Beside that, indicator is needed to identify the change color when meet approximate the pH like as phenolphthalein during the reaction of two colorless substances such as NaOH and HCl. End point, which neutralize between acid and base, is appeared base on the indicator.

Other attentions, these are titre and equivalence point. Firstly, the term is based on the burette bring the titrant to reach end point.Secondly, the term is based on the point in the titration where the titrants is added enough to neutralize the analyte and the mole of titrant is equal to the mole of analyte.

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Salt and water will be produced by the reaction between NaOH and HCl, calculate the concentration by this equation:

NaOH(aq) + HCl(aq) -> NaCl(aq) + H2O(aq)

Equation:Concentration(M) = Moles(mol) / Volume(L)

Hypothesis

Through the experiment, the solution will have pale pink at the end and the volume of the NaOH needed is similar with the volume of HCl because they have ratio 1:1, so the mole may be similar.

Assuming, the concentration of HCl is about 1M and the concentration of NaOH is about 1M, similar HCl

Variable

Independent Variable: The volume and concentration of NaOH

Dependent Variable: The neutralization of the reaction

Control Variable: The volume of HCl and unknown concentration solution

Error controlled:

There are some error that can occur. Firstly, the addition of NaOH is too much so the result is inaccurate. Secondly, the concentration is not enough because the students using many thing to measuring. Finally,The reaction happen before titration, so every equipment should be cleaned clearly before doing experiment. They will be fixed by carefully and done step by step.

Procedure

1. 25ml of HCl is measured by a measuring cylinder and is added to a conical flask. A few drops of phenolphthalein is added to the solution as well
2. A funnel is used to fill NaOH in the burette until it reaches zero mark. A beaker is used to store any excess acid if any
3. NaOH is then added to the HCl solution in small volume and the solution is swirled after addition. This process continues until the solution turns pale pink and result is recorded.
4. After the volume of NaOH is known, a new set of NaOH with that known volume is added to 25ml of HCl to produce a neutral solution
5. The solution is then evaporated down to half of the volume by using an evaporating dish on a gauze over a Bunsen burner
6. The solution is then left on the crystallising dish to produce a white crystalline solid

Observation And Data

Volume of NaOH added to HCL. Both with known concentration:

Run 1 Run 2 Run 3

Final Volume (mL) 42 40.5 40.5

Initial Volume (mL) 0 0 0

Titre (mL) 42 40.5 40.5

Mean titre (mL) 41

In run 1 and 2, physically, when NaOH is added the solution turn to dark pink. But in run 3, it turns to pale pink.

Volume of NaOH added to H2SO4 which has unknown concentration

Run 1 Run 2 Run 3

Final Volume (mL) 28.8 30.8 30

Initial Volume (mL) 0 0 0

Titre (mL) 28.8 30.8 30

Mean titre (mL) 29.8

In run 1,2 and 3, physically, when NaOH is added, the solutions turns from colorless to pale pink

Analysis

Base on data above, NaOH is around 29.8 mL and 41 mL that neutralize the xM H2SO4 and 1M HCl while the indicator phenolphthalein make change pale pink when meet basic , respectively. Because the basic after neutralization changes the pH number of solution, phenolphthalein change color.

As for H2SO4, its unknown concentration can be calculated by formula:

M1 x V1 = M2 x V2. M1 is the concentration of H2SO4, V1 is the volume of H2SO4, M2 is the concentration of NaOH and V2 is the volume of NaOH. Volume is in Litre.

M1 x V1 = M2 x V2 => M1 x 0.025 = 1 x 0.0298 => M1 = 1.192 mol/L.

Beside that,the concentration of HCl is 1.64 mol/L.

Conclusion

The concentration of HCl is quite different from my hypothesis which identify it will be 1M. Additional, the concentration of 1.192 mol/L H2SO4 is used for neutralizing 1M of NaOH. But it can not be compared without hypothesis existed.

The results could be inaccurate due to the exactly in volume. The color of titrated solution should be pale pink, but 2 over 6 my trial is dark pink by adding NaOH so fast. If I would do experiments again, I would carefully titrate the solution to pale pink for exactly calculating.

Titration is very useful in real life such as determine the concentration of chemical substances in blood or medicine for developing new medicine . In addition, it helps in the food industry in order to balanced the used chemical in production.

Reference

1. Stubbings, J. (2019). Titration Techniques Chemistry Tutorial. [online] Ausetute.com.au. Available at: https://www.ausetute.com.au/titrtech.html [Accessed 25 March 2019].
2. Chemguide.co.uk. (2019). acid-base indicators. [online] Available at: https://www.chemguide.co.uk/physical/acidbaseeqia/indicators.html