EXPERIMENT: Effect of Dissolved Carbon Dioxide on the pH of water

1725 Words Jul 20th, 2008 7 Pages
HSC BIOLOGY ASSESSMENT TASK 1 Conductor: Wissam Bardouh

HSC BIOLOGY ASSESSMENT TASK 1

MAINTAINING A BALANCE

TASK: OPEN-ENDED INVESTIGATION

Our task is to plan, choose equipment and perform a first hand investigation to demonstrate the effect of dissolved carbon dioxide on the pH of water.

DUE DATE: 21/11/07

CONDUCTOR: Wissam Bardouh

EFFECT OF DISSOLVED CARBON DIOXIDE (CO2) ON PH OF WATER

Introduction:

((Carbon Dioxide is a greenhouse gas. It is everywhere ranging from our bodies to the atmosphere. Carbon dioxide is produced in living organisms as a result of cellular respiration (glucose + oxygen -->carbon dioxide + water + energy). It occurs in high concentrations in the tissues in our body. It then diffuses in the circulatory
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The 3 remaining beakers were blown into through a straw for 2 min and step 5 was repeated for each of the beakers.

Results were tabulated and graphed.

*The dependent variable is the initial pH of the water

*The independent variable was the amount of time spent exhaling

*The constant variables were:

-amount of water used in each trial

-size of beaker in each trial

-size of straw in each trial

*The control was the beaker with water but no blowing into it

Diagram:

Safety glasses

Straw pH probe

pH probe

Stopwatch

Beakers

Limewater

Results:

TRIAL 1

TIME

CHANGE IN pH LEVEL

0 sec

8.3

40 sec

6.4

1 min 20 sec

6.2

2min

6.1

TRIAL 2

TIME

CHANGE IN pH LEVEL

0 sec

8.3

40 sec

6.7

1 min 20 sec

6.2

2min

6.1

TRIAL 3

TIME

CHANGE IN pH LEVEL

0 sec

8.3

40 sec

6.8

1 min 20 sec

6.3

2min

6.1

CONTROL

TIME

CHANGE IN pH LEVEL

0 sec

8.3

40 sec

8.3

1 min 20 sec

8.3

2min

8.3

Discussion:

After conducting the experiment it was observed that my hypothesis was answered in the sense that adding dissolved Carbon Dioxide to water will cause its pH to decrease, therefore making it acidic. It was also observed that the more time spent exhaling through a straw into the water, the lower the pH. Choosing the correct method was quite a challenge for me, as there were many ways in which this experiment could've been conducted. After researching the different methods, I chose to go with
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