MissRose
New Member
I was wondering if in an exam you are asked to evaluate an experiment what do you write?
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Evaluate??? (1 Viewer)
- Thread starter MissRose
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felafel
Member
Validity - does the experimental procedure address the aim of the experiment?
Reliability - is the experimental procedure correct? eg. when preparing a standard solution for titration, was the volumetric flask filled so that the BOTTOM of the meniscus was in line with the mark?
Risk Assessment - blab on about Bunsen Burners - direct, indirect burning, acids, etc.
Reliability - is the experimental procedure correct? eg. when preparing a standard solution for titration, was the volumetric flask filled so that the BOTTOM of the meniscus was in line with the mark?
Risk Assessment - blab on about Bunsen Burners - direct, indirect burning, acids, etc.
MissRose
New Member
thanks
Tahnks for that..it helped alot but i still have to work on it abit more.
In regards to titration what kind of questions could we be asked?
Tahnks for that..it helped alot but i still have to work on it abit more.
In regards to titration what kind of questions could we be asked?
You could be asked about whether a properly performed titration is reliable and accurate. You could be asked about the impact on each of these of various mistakes - like filling past the graduation mark in the volumetric flask (no effect on reliability, but reduces accuracy), or of washing the burette with water (decreases both accuracy and reliability). You could be asked how they might be improved - for example, dilution can improve accuracy, as there are less moles per drop.
With respect to validity, you could be asked things like the effect of using the wrong indicator - this could render the experiment invalid, in which case it will also be inaccurate, but it would still be reliable.
You could possibly even be asked about other factors thta might invalidate an experiment - for example, when I was at school, we did a titration to determine the quantity of aspirin (acetylsalicylic acid) in a headache tablet, by titration with NaOH - the results were way off because the design of the experiment was invalid. This was becasue the tablet contained 30 mg of aspirin and 300 mg of citric acid, and of course both reacted with the NaOH.
You could also be asked about safety - there's not a huge amount to say about a titration safety wise, but you can always find something to talk about - such as with dealing with pipettes, how to avoid the risk of stabbing yourself by incorrectly putting on the pipette filler. Most indicators are not good for you as well - phenolphthalein, for example, is a powerful laxitive - so usual safety precautions to prevent ingestion, etc.
With respect to validity, you could be asked things like the effect of using the wrong indicator - this could render the experiment invalid, in which case it will also be inaccurate, but it would still be reliable.
You could possibly even be asked about other factors thta might invalidate an experiment - for example, when I was at school, we did a titration to determine the quantity of aspirin (acetylsalicylic acid) in a headache tablet, by titration with NaOH - the results were way off because the design of the experiment was invalid. This was becasue the tablet contained 30 mg of aspirin and 300 mg of citric acid, and of course both reacted with the NaOH.
You could also be asked about safety - there's not a huge amount to say about a titration safety wise, but you can always find something to talk about - such as with dealing with pipettes, how to avoid the risk of stabbing yourself by incorrectly putting on the pipette filler. Most indicators are not good for you as well - phenolphthalein, for example, is a powerful laxitive - so usual safety precautions to prevent ingestion, etc.
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