Few questions (1 Viewer)

[FlyingKanga]

Hey guys, I've got this biology assessment due on the syllabus dot-point -
Identify data sources, plan, choose equipment or resources and perform a first-hand investigation to test the effect of:
-Change in Temp
-Change in pH

Two questions regarding it.
If I mix an acid and a base to get my specific pH, will this affect the reaction/result because of the additional salt produced from the reaction? If so, what would be a better way to get different pH levels?

Also, do teachers usually want the rate of reaction or the amount of O2 bubbles produced in the results?

 

[BoredofBoredofS]

The usual procedure for obtaining specific pH's is to simply find a substance that has that pH - if you mix an acid with a base, you neutralise it and form water and a salt. If you're unable to get substances with pH's, you can always try diluting the more acidic/alkaline solutions to reach the desired pH - however this is inaccurate as well. Your science lab should have solutions with varying pH's, so there shouldn't be a need to experiment to form a 'new' pH.

Regarding your other question, i'll assume that you are performing the experiment regarding catalase and hydrogen peroxide - in that case, the rate of reaction is irrelevant. After a set amount of time you record the height of the oxygen bubbles, which should provide an indication of how effective each pH was at breaking down the peroxide into oxygen. You COULD measure the rate of reaction by measuring time time it takes for the bubbles to reach a certain height, but both methods provide similar results.