Friday, 11 February 2011
9:12 AM
Aim: To investigate the conductivity of different pH levels.
Introduction:
The pH is a figure which indicate the acidity or alkalinity of a solution on the scale of 0-14. The midpoint on the scale is 7 which is neutral, water is neither acidic or basic. Numbers below 7 would indicate that the solution is an acid and the lower the number the more acidic it is. The same goes for alkaline solution, numbers above 7 indicate that the solution is a base and the higher the number the more basic it is. Acids and bases both contain ions of the element hydrogen which allows us to measure the pH of a solution. A change of one pH unit changes the hydrogen ion concentration by a factor of ten. For example, a solution of ph1 has ten times more hydrogen ion concentrations than a pH2 which means that a solution of pH1 has one million more times hydrogen ion concentrations than a pH7. Conductivity is the ability to conduct an electric current, if there are more hydrogen ion concentrations then more electricity would flow through because travels through water faster.
Variables:
Independent- pH levels of baking soda and salt
Dependent- ampere and voltage
Materials:
- Connecting wires
- Power supply
- DC ammeter
- DC voltmeter
- Two beakers
- Deionised water
- Baking soda
- Salt
Risk assessment:
The risk involved in this experiment include spilling the solution onto yourself , as it may be harmful to your skin. To prevent this from happening, be careful when you're handling the beaker.
Discussion:
Through the resultant data it can be seen that though the basicity of the solution is a factor which will increase the conductivity of the water. Though this is the case, on a closer examination of the results and graphs it is evident that it is not the pH of the water which
contributes to the conductivity, as it can be seen that the pH of 8 with 3 teaspoons of salt and the pH of 8 with 1/3 teaspoons of sodium bicarbonate has different conductivity. As the salt solution has the higher rate of ions in the solution compared to the sodium bicarbonate solution. The amount of
solvent or ions which has been placed into the deionized water is the component of the circuit which will increase the conductivity of the circuit. Furthermore, the increase in both the graphs is also evidence that the ions in the solution will also contribute to the conductivity of the water. Which
hence, concludes that due to the results with the same pH having different conductivity rates it is evident that it is due to the amount of substances in the solution as when there was no solute in the solution (deionized water there was no current flowing through.
However, through the experiment ran smoothly, many errors have crept up. As shown the method galvanized rods were missing and could have caused corrosion in the metal alligator clips. This would have hindered the results as the corrosion might have provided extra resistance and more ions in
the water. However, the data presented showed that each pH level of salt to the same pH level of Sodium Bicarbonate had distinctly higher current flow than the other which could not have been achieved with a minimal rusting effect. Furthermore, the use of universal indicator could have been detrimental to our results as the data was qualitative data with no exact number this could have
meant that the solutions were at different pH levels than the ones recorded. Finally, the use of a teaspoon instead of measuring the compounds was a mistake as it was not an exact number causing errors which were not extremely fatal as the results are too far apart to be consider the ____ to be wrong.
Conclusion:
Conclusion – the aim was successfully achieved with gained information. It was achieved as the examination of the basicity of water was established concluding that the more basic the solution was the more conductive it was, as the solution would contain more ions in it, for example, pH 10 in the salt solution had 200A flowing through it and the pH 10 sodium bicarbonate solution had only 30A. And h
And hence, from this we can also conclude that the more acidic the solution was the more conductive it would be as well
