Gas Emission from an Alka-Seltzer Tablet

Concentration

The Collision Theory

The collision theory explains why surface area can affect the speed (rate) of a reaction. When the particles collide more often in a certain, reactions speed up. A chemical reaction only works if the atoms (or molecules) are colliding.

The effect of surface area

* When a solid lump is cut into smaller pieces its surface area is increased and its rate of reaction increases.

* In a lump of material, the particles do not collide very often; therefore the rate is slow.

* With a powder, lots of particles are exposed and the rate can be very, very, fast.

Diagram of Apparatus

Method

We set out the experiment as in the diagram. Then I got the measuring tube and filled it completely with water placing my hand over the top I then place it into the water not letting any escape. I placed the end over the collecting tube. I then took the conical flask, which in I placed 100cm³ of water, this was room temperature. (This was for the room temperature experiment). I then got an Alka-Seltzer tablet opened the packet and places it into the conical flask placing the bung in and starting the stop clock. When the gas from the tablet had finished pushing all the water from the measuring tube I stopped the clock and wrote down the time in my book. I did each experiment three times so that an average could be found. I repeated the experiment for 40ºC, 60ºC and 80ºC each time taking tree readings and taking the average.

When these four experiment were done I decided to look at surface area, so I took an Alka-Seltzer tablet and cut it in half, took another and cut it into quarters, another which I crushed into powder. I repeated the experiment with each of these different surface areas using 100cm³ of water at room temperature and took down the results.

Predictions

I predict that the whole Alka-Seltzer tablet will produce gas fairly quickly at room temperature as the temperature increases so will the rate of reaction and the rate that the gas gas is produced. When the tablet is cut into smaller pieces and the surface area is increased the rate the reaction takes place will be faster and will produce the gas much quicker.

Results

Temperature

2

3

Average

Room temp. 20ºC

45.65s

44.84s

46.38s

45.62s

40ºC

2.68s

7.56s

7.75s

9.33s

60ºC

5.43s

5.12s

4.78s

5.11s

80ºC

4.46s

4.43s

4.93s

4.94s

Tablet Size

2

3

Average

Whole tablet

55.01s

56.57s

56.60s

56.06s

Crushed tablet

37.76s

35.65s

36.07s

36.16s

Half

44.43s

43.12s

43.50s

39.32s

Quater

39.05s

38.76s

40.15s

39.32s