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pH experiment (2 Viewers)
- Thread starter *ccs*
- Start date
Kyroth***
Member
I did dry ice and data loggers. I had it for my trial too!
There are only so many pracs they can ask for for bio, and thats one of the better ones, cos its and actual PRAC prac, where you can have an actual method, not like "look through the microscope and record what u see".
I'm more worried about chem with pracs. *shudders*
There are only so many pracs they can ask for for bio, and thats one of the better ones, cos its and actual PRAC prac, where you can have an actual method, not like "look through the microscope and record what u see".
I'm more worried about chem with pracs. *shudders*
stu_jacks88
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I had it for my trial as well, but we had to write out both the blowing through the straw one, AND the calcium carbonate/sulfuric acid one. Bastards. i only did the calcium carbonate one for the actual test.
Oso
Biotechnician in Training
Did anyone remember to do a risk assesment?
The_highwayman
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did it ask for it? i thought it just asked for method, variables and reliability?
i did the blowing into a straw one
Variables: independent - Carbon dioxide
Dependent: pH of water
Method: Blah blah
Reliability: tested in lime water
used a control.
damn, i should have said i repeated it 20 times. XD
i did the blowing into a straw one
Variables: independent - Carbon dioxide
Dependent: pH of water
Method: Blah blah
Reliability: tested in lime water
used a control.
damn, i should have said i repeated it 20 times. XD
Oso
Biotechnician in Training
Teachers at my school who are HSC markers told us, that even if they don't ask for one that you should give one, 'cause it's gonna be in the marking criteria.
MiniT
Merlin The Sorcerer
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I did the bubbling expired air into a test tube one. I basically wrote that you first bubble expired air in a test tube of lime water to confirm that CO2 is present. Then you set up 2 tt with equal amounts of tap water and add 2 drops of universal indicator. Bubble expired air into one and compare the colour change. Repeat the experiment many times for reliability. Variables are the size of the test tubes, the amount of time you bubble for, the amount of water etc etc.
The_highwayman
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Please read two posts above your post.Bboymot said:
Alternatively, here is the link to save you some scrolling
http://community.boredofstudies.org/showpost.php?p=1979116&postcount=26
Hold on!Bboymot said:
Proving that exhaled air contains CO2 is how you ensure the VALIDITY of the experiment, i.e. that the experiment tests what it is actually supposed to measure. So you breathe into limewater=turns milky. Therefore exhaled air has CO2.
However, the question asked for the REALIBILITY of the experiment, i.e. the repeatability of the experiment. So you show it is reliable if you repeat it a few times and the same result occurs. So it is RELIABLE. You should also have a tight control on variables (such as those described in your method) so that if the experiment were carried out by someone else the same result would occur.
Reliability and validity are completely different things. An experiment can be valid without being reliable or reliable without being valid.
What did I do? I mentioned breathing into limewater at the beginning of my prac but I put in brackets that this was for validity.
At least that's how I interpreted the question.
