Report

Aim

Concentration is the abundance of a constituent divided by the total volume of a mixture. This experiment explores how concentration affects the speed of a chemical reaction or the rate of reaction.

Hypothesis

The higher the concentration of the vinegar, the faster the rate of reaction. The lower the concentration of the vinegar, the slower the rate of reaction.

Background

When baking soda and vinegar is put together, something new is created. Baking soda and vinegar react chemically because one is a base and the other is an acid. Baking soda is a basic compound called sodium bicarbonate. Vinegar is a diluted solution that contains acetic acid. The reaction between these two reactants generates carbon dioxide gas. Just like carbon dioxide bubbles in a carbonated drink, the carbon dioxide rises to the top of the mixture. This creates the bubbles and foam you see when you mix baking soda and vinegar. Does the concentration of vinegar affect the rate of reaction?

Method

Prepare the materials according to the list above.
Add 100 mL of vinegar into conical flask A.
Add 75mL of vinegar and 25mL of water into conical flask B.
Add 50mL of vinegar and 50mL of water into conical flask C.
Insert 10g of baking soda into three balloons.
Place a balloon on each of the conical flasks.
Lift all three balloons at the same time to pour the baking soda into the vinegar solutions.
Observe the changes in the size of the balloons.

Discussion

In this experiment, the changing factor, vinegar concentration in each conical flask, indicates the effects of concentration on the rate of reaction. As shown in the image above, the blue balloon has been filled with the most carbon dioxide (product of vinegar and baking soda). The carbon dioxide in the balloons indicates the rate of reaction – the more carbon dioxide is produced, the higher the rate of reaction. Other than the concentration of vinegar in the conical flasks, everything else is kept constant to ensure a fair experiment so errors can be prevented. Through this experiment, it is shown that the higher the concentration of vinegar, the higher the rate of reaction as more carbon dioxide is produced.

Conclusion

The higher the concentration, the quicker the rate of reaction. The lower the concentration, the slower the rate of reaction. The balloon with a lesser concentration of vinegar increased in size slower than the balloon with higher concentration as carbon dioxide is less due to the reaction rate.

Yes, our hypothesis was supported by the results. The increase in the rate of reaction due to higher concentration is because of the greater chance of reactant particles colliding within the same amount of time, thus the frequency of success between particles increases. With more successful collisions, the rate of reaction increases.

find a .pdf file of the report here

Concentration

Materials

Vinegar 225mL
Baking soda 30g
Spatula
Glass watch
Weighing scale
3 balloons
3 conical flasks
Stopwatch/timer

Variables

Independent: Concentration of vinegar solution
Dependent: Size of balloon
Controlled:
- Amount of vinegar solution
- Amount of baking soda
- Time taken to complete the experiment
- Type of balloon
- Type of baking soda
- Timer/stopwatch used

Safety

If you accidentally spill water, wipe out the water as soon as possible and seek help from supervising parents/guardians if necessary. This is because someone could slip.
If vinegar or solutions enter eyes, nose or mouth, seek help from a parent to rinse with water immediately.
Handle solutions with a lot of care.
Wear covered shoes and aprons.
Do not walk barefooted.

Results

Conical flask A (which has 100mL vinegar) caused the balloon to increase the most in size. Conical flask B (which has 75mL vinegar and 25mL water) caused the balloon to increase the second most in size, and conical flask C caused the balloon to increase the least in size.