Chemistry Project – Titration

Charis Chan(1)

Shita Chan (2)

Angela Chau(3)

Carol Hung (13)

Joey Wong (34)

The Problem Through this experiment, we want to compare the lemon juice and the fresh lemon juice which one is better buy.

Name and cost of the brands of the produces to be investigated

Brand Cost($)Lemonade CCLemon 17.9Fresh lemon / 2.5/one

Apparatus and materials

Apparatus and materials Number

Beaker (200ml) 2

Glass rod 2

Phenolphthalein 1 bottle

Sodium hydroxide 2 bottle

(0.1M & 1M)

Burette 1

Pipette 2

Pipette filler 1

Conical Flask 2

stand and clamp 2

measuring cylinder 2

Safety Precaution• Make sure the burette keep safely in the stand and clamp before doing

titration • Wear safety gloves while performing the experiment

Procedure [Lemonade (CC Lemon) & Fresh Lemon]

1. Run down of the titration of lemonade (CC Lemon)

NaOHStand and Clamp

Pipette

1. Wash the burette with distilled water. Then, use NaOH to wash the burette.

2. Place 25.0 cm3 of lemon juice in a conical flask. Add 2 drops of phenolphthalein to the flask.

3. Phenolphthalein becomes colourless in an acid4. Place NaOH solution in a

burette.

5. Run the NaOH solution from the burette until the colour of phenolphthalein

just change from colourless to red.

6. Calculate the volume of the NaOH solution required to neutralize the citric acid in the lemon juice.

7. Repeat the experiment for several times.

Run down of titration of Fresh lemon: 1. Wash the burette with distilled water. Then, use NaOH to wash

the burette.

2. Place 25.0 cm3 of fresh lemon juice in a conical flask. Add 2 drops of phenolphthalein to the flask.

3. Phenolphthalein becomes colourless in an acid.4. Place NaOH solution in a burette.

5. Run the NaOH solution from the burette until the colour of phenolphthalein just change from colourless to red.

6. Calculate the volume of the NaOH solution required to neutralize the citric acid in the fresh lemon juice.

7. Repeat the experiment for several times.

Results (Table form):

Lemonade (CC Lemon)Burette reading (cm3)

Titration 1st 2nd 3rd 4th

Final reading 14.1 28.4 43.1 58.1

Initial reading

0.2 14.1 28.4 43.1

Fresh Lemon Juice

Burette reading (cm3)

Titration

1st 2nd 3rd 4th

Final reading 14.2 27.4 41.2 54.7

Initial reading 0.1 14.2 27.4 41.2

After the experiment, calculated the mean number of

mole of citric acid used in the experiment of two type of

the lemon juice

1. Lemonade – CC Lemon

•The volume of NaOH:

[(28.4-14.1)+(43.1-28.4)+(58.1-43.1)] ÷3=(14.3+14.7+15) ÷3=14.7cm3

•No. of mole of NaOH = 0.1 x (14.7 ÷1000)=0.0147 mole

•No. mole of citric acid in 25 cm3 = 0.0147 mole

2. Fresh Lemon Juice • The volume of NaOH :[(27.4-14.2)+(41.2-27.4)+(54.7-41.2)÷3=(13.2+13.8+13.5) ÷3=13.5 cm3• No. of mole of NaOH = 0.135 mole• No. of mole of citric acid in 25cm3 = 0.135mole

Calculated the money need to use for each mole of the

type of the lemon juice

1. Lemonade - CC LemonThe cost of lemonade used in the experiment:$17.9 x (1/5)=$3.58

Price/mole:$3.58/0.135=$27/mole

2. Fresh Lemon JuicePrice/ mole:$2.5/0.135=$18/ mole

The type which has a lower price per one mole, which

means it is better buy.

Conclusion

• By comparing the fresh lemon juice and lemonade, one mole of fresh lemon juice ($18) is better buy than one mole of lemonade ($1218).

Reflection:

• We may have some error for the initial reading and the final reading, because we didn’t read the meniscus through eye level.

• We should filter the fresh lemon juice at home but not at the laboratory because this waste a lot for time.

Difficulties

• It is difficult to choose whenther we should use 0.1M or 1.0M NaOH to titrate with the critic acid.

• We don’t know how much critic acid we need to prepare for the experiment because we afraid that there is not enough solution for the experiment.

• As the result, fresh lemon is better buy.

THE END