Chemistry - Practical Report

[Jakeybaby]

Hi Guys,

 I know that this is SACE but no one on here is from South Australia so thought that this was the best place to post to get the sufficient help.

I just completed a practical today regarding a Galvanic Cell, see attached documents.

I was just wondering if anyone had any ideas on any potential errors that could have occured? Looking for those A+ errors which are above the standard errors which are regularly mentioned.
Currently some of the errors which I have other than the standard C level ones:
- Ambient Temperature Changes = Affect in Voltage
- Inaccurate Dilution ==> Inaccurate Concentration

Any other ideas to answer any of the remaining sections from errors down on the marking scheme would also be greatly appreciated!

Thankyou!
Jake

[zsteve]

Yes, the Nernst equation is used to predict cell voltage away from standard conditions.

- Contamination if applicable? (we used this in analytical chem pracs, e.g. titrations all the time)
- H2CO3 (Carbonic acid) present in water (from atmospheric CO2). This might have some effect on your reaction or titration results.

I haven't taken the time to read through the information in detail, but hopefully the above might be applicable, or give you some inspiration.

At least in VCE, teachers are really just looking for an awareness of errors, so the point is to find SOME errors, rather than finding 'A+ errors' which are so esoteric that no-one will think of them.

[Jakeybaby]

I would appreciate any feedback on the new document which I have uploaded, this is the updated copy of my practical report.

[jakesilove]

I would appreciate any feedback on the new document which I have uploaded, this is the updated copy of my practical report.

Hey! Not a problem

I think you could probably expand on the controlled variables. Things like temperature, beakers etc. are all things that should be kept constant as well. You've definitely noted the important ones, but it's always useful to show that you've thought a bit beyond what most students will have.

I don't know how methods are taught in SA, but generally you're supposed to write in past tense. This just makes it easier to follow, and is standard scientific practice. So, instead of

1.   Rinse both 100mL beakers with the distilled water provided.

you could write

1.   Both 100mL beakers were rinsed thoroughly with distilled water.

This may not be relevant to your assignment, but just in case it is I thought I would let you know!

You might want to use a calculation for step 15. where you dilute the substance. C1V1=C2V2 will be your friend there. You can definitely write out calculations at the end (eg. use a subheading called "calculations") and then in the method say something like "refer to Calculation #1". Looks super sciencey.

In your results table, whilst its obvious that your average is also in Volts, it doesn't explicitly say so. Teachers can be brutal about this sort of thing, so watch out for that.

I would probably used as the x-axis units on your graphs, but that's not too much of a problem. Definitely like that you've used two graphs!

Your discussion is really good. I would recommend subheadings; particularly "Accuracy, Reliability and Validity" as this is really the important stuff. That will depend on what your teacher really wants though.

If you wanted to extend yourself, I wonder whether you could find an equation that DOES let you predict voltage in non-standard conditions, and see if your data roughly fits with that equation (it will). The Nernst equation comes to mind; definitely not necessary, but possibly a good way to impress your teacher.

Great response overall! Let me know if you want me to take a look at anything else.

Jake

[Jakeybaby]

Hey! Not a problem

I think you could probably expand on the controlled variables. Things like temperature, beakers etc. are all things that should be kept constant as well. You've definitely noted the important ones, but it's always useful to show that you've thought a bit beyond what most students will have.

I don't know how methods are taught in SA, but generally you're supposed to write in past tense. This just makes it easier to follow, and is standard scientific practice. So, instead of

1.   Rinse both 100mL beakers with the distilled water provided.

you could write

1.   Both 100mL beakers were rinsed thoroughly with distilled water.

This may not be relevant to your assignment, but just in case it is I thought I would let you know!

You might want to use a calculation for step 15. where you dilute the substance. C1V1=C2V2 will be your friend there. You can definitely write out calculations at the end (eg. use a subheading called "calculations") and then in the method say something like "refer to Calculation #1". Looks super sciencey.

In your results table, whilst its obvious that your average is also in Volts, it doesn't explicitly say so. Teachers can be brutal about this sort of thing, so watch out for that.

I would probably used as the x-axis units on your graphs, but that's not too much of a problem. Definitely like that you've used two graphs!

Your discussion is really good. I would recommend subheadings; particularly "Accuracy, Reliability and Validity" as this is really the important stuff. That will depend on what your teacher really wants though.

If you wanted to extend yourself, I wonder whether you could find an equation that DOES let you predict voltage in non-standard conditions, and see if your data roughly fits with that equation (it will). The Nernst equation comes to mind; definitely not necessary, but possibly a good way to impress your teacher.

Great response overall! Let me know if you want me to take a look at anything else.

Jake

Thankyou for this feedback, really appreciate it!

I had just copy & pasted my method from the task that we had to complete before the practical, I had changed it to past tense but yet I didn't upload the new document.

Thanks again for you help!

[keltingmeith]

Alright, so Jake may have hit some of the same points, but it was a little annoying to jump between the two - so if we hit the same point, that just means you really should change it. Overall, it's a good report, regardless of how much red you see - if I saw something that didn't need changing, I didn't touch it, pretty much. (with the exception of the end, because it just got too long and repetitive...) And one note I didn't add in: use your English writing skills!! (are you doing English, on that point...? Because you do SACE, yeah?) Just because they're different subjects, that doesn't mean they shouldn't interact.