Science QuizTeeth test

By F. 4E

Group List Leung Chi Heng Cheung Long Hang Ho Yik Ki Chan Kan Hei

Content P.1 Purpose P.2 Hypothesis P.3-4 Experiment design P.5 Apparatus P.6 Materials P.7-8 Procedures P.9-12 Results P.13 assumption P.14-15 conclusion P.16 Error

Purpose

To determine whether toothpaste can protect teeth from decaying ;

And which toothpaste can protect teeth better.

Hypothesis

Our first hypothesis was that all toothpastes can protect teeth from decaying.

Our second hypothesis was that Colgate toothpaste could protect teeth from decaying most effectively.

Experiment design (1)

The constants in this study were:1. Number of egg(1 egg) 2. Type of egg3. Type of acids (hydrochloric and carbonic acid) 4. Concentration of acids 5. Quantity of acid (40mL)6. Quantity of toothpaste7. Amount of time to keep the teeth in acid (20 hours)

Experiment design (2)

The manipulated variables:1. Presence of toothpaste2. Type of toothpaste (Lion 獅王 , Colgate, Darlie 黑人 and Oral B )

Responding variables:1. The appearance of the tested egg’s surface2. The mass of the tested egg

Apparatus

Quantity 10 4 1 1

Item Beakers(100mL size)

Beakers(?00mL size)

Electrical balance

Hair Dryer

Quantity 4 1 4 1

Item Bunsen burners

Dry towel Safety glasses

Pile of label paper

Quantity 4 4 1 1

Item Tripod Heat-proof mat

Starter Camera

MaterialsQuantity (M)

10

Item Eggs Oral Btoothpaste

Lion( 獅王 ) toothpaste

Darlie( 黑人 )toothpaste

Quantity (M)

200mL 1 (200mL)

Item Colgate Toothpaste

Dilute hydrochloric acid (2M)

Coca-cola(carbonic acid)

Procedures (1) 1. Boil the eggs. 2. Dry the eggs with a hair dryer

and a dry towel. 3. Label the beakers with label

paper (A1, A2, B1, …, D2) 4. Mark down their appearance by

taking photos. 5. Measure the mass of eggs by the

electrical balance. 6. Put a thin layer of toothpaste on

the eggs 7. Put the eggs in beakers. 

Procedures (2) 8. Pour 40ml of hydrochloric acid on each of

them. 9. Repeat step 8 except using coca-cola

(carbonic acid).  Keep it in acid for 20 hours

10. Wash away the toothpaste. 11. Dry it up. 12. Mark down their appearance by taking

photos. 13. Measure the mass of the eggs. 14. Calculate the %change of mass of the

eggs. * Control: Repeat steps 1-14 without adding

toothpaste

Results The result of this experiment were:

(With HCl)

All the toothpaste we tested , reduced the mass losses of the eggs ,comparing with that of the egg without toothpaste.

Overall , mass loss of egg with Lion toothpaste was the least, then Colgate, and then Oral B, the most was Darlie.

Results 2

Actually,we have also used coke to test the eggs.

But it failed as we found the mass of the eggs are heavier than it was!

We think that this may be caused by the absorption of coke, as the coke contains other substances

Result comparing

Appearance changeBefore after

Assumption

The higher degree of reducing mass loss,the higher efficiency of protecting teeth.

Conclusion Our first hypothesis was that all toothpastes can protect

teeth from decaying. The results indicate that this hypothesis should be

accepted. Our second hypothesis was that Colgate toothpaste would

be the most effective at protecting teeth. The results indicate that this hypothesis should be

rejected. According to our result ,Lion toothpaste can protect teeth

better than Colgate toothpaste.

Source of Error

The surface areas of the eggs are not equal. The distribution of toothpaste on the eggs

may not be even. The eggs may absorb the acids which cause

an increase in mass.

Special Thanks

Mr Yu. Mr Lee ,the chem. lab technician. Mr Andy.Tse. Science society.

The End

Thank you for your attention!