VCE Chemistry Question Thread

[Buddster]

When working through a question, do I round to appropriate sig figs at each step, or just for the final answer? In most cases, it shouldn't matter, but what is the correct way of doing it? Similarly, do I use a rounded value for the next step in my calculation, or just use the full (as many decimal places as possible) value on my calculator?

Thanks!

Best way IMO:
Write only in sig figs, but use full value in calculator

[sweetiepi]

When working through a question, do I round to appropriate sig figs at each step, or just for the final answer? In most cases, it shouldn't matter, but what is the correct way of doing it? Similarly, do I use a rounded value for the next step in my calculation, or just use the full (as many decimal places as possible) value on my calculator?

Thanks!

Hey!

Always display the unrounded number in working, right up to the final step (although it is fine to go 1.23456... (unit) ). Just remember to use the correct number of sig figs in your final answer!

With calculator use, alslways, always, always use the unrounded figure, to reduce error!

Edit: beaten by Buddster

[Jakeybaby]

When working through a question, do I round to appropriate sig figs at each step, or just for the final answer? In most cases, it shouldn't matter, but what is the correct way of doing it? Similarly, do I use a rounded value for the next step in my calculation, or just use the full (as many decimal places as possible) value on my calculator?

Thanks!

Usually sig figs are only allocated marks for your final answer, so whatever you write previous to that should not lose any marks. I personally write out more decimal places that what are required from the question, that's the best way that I find.  However, it is important to always use the full values from your calculator, i.e. rather than typing in 5.13521..., use the "Ans" key, this will increase the accuracy of your answers.

[keltingmeith]

See, in working, I like to round off at every step. That way it serves as a reminder of what my lowest number of sig figs is.

Eg, 2.102+3.5=5.6
5.6*2.111=12
12/2.512=4.7

In this case, if I didn't round off to 2 at every step, I might've forgotten that my answer should've been 2 sig figs. Use full values in your calculator, though, as everyone above said.

[peanut]

Thanks everyone! I understand it now

Another quick question, is my answer incorrect or equivalent to the suggest answers?

What is the condensed formula of the hydrocarbon? (see attachment)
I wrote CH3C(CH3)(CH3)(CH2)4CH3 but the answer is (CH3)3C(CH2)4CH3

What about CH3C(CH3)2(CH2)4CH3?

[keltingmeith]

Thanks everyone! I understand it now

Another quick question, is my answer incorrect or equivalent to the suggest answers?

What is the condensed formula of the hydrocarbon? (see attachment)
I wrote CH3C(CH3)(CH3)(CH2)4CH3 but the answer is (CH3)3C(CH2)4CH3

What about CH3C(CH3)2(CH2)4CH3?

As far as I'm concerned, they're all equivalent. The answer they gave might be the most correct because it's the most condensed, though.

[Jakeybaby]

Thanks everyone! I understand it now

Another quick question, is my answer incorrect or equivalent to the suggest answers?

What is the condensed formula of the hydrocarbon? (see attachment)
I wrote CH3C(CH3)(CH3)(CH2)4CH3 but the answer is (CH3)3C(CH2)4CH3

What about CH3C(CH3)2(CH2)4CH3?

I personally don't agree with the suggested answer.
I would suggest that the answer would be:

CH₃C(CH₃)₂(CH₂)₄CH₃
My understanding is that the two CH₃ groups should be enclosed in parentheses after the carbon atom to which they are attached.

[pap0007]

hi all! i just got the results for my chemistry subject as i picked up the unit 3 and 4 in year 11 and i was wandering if this was the raw score that i got or the scaled score?

[Buddster]

hi all! i just got the results for my chemistry subject as i picked up the unit 3 and 4 in year 11 and i was wandering if this was the raw score that i got or the scaled score?

RAW, you find out scaled when you get your ATAR

[homosapien]

Hi guys
Im a bit stuck on how to prepare for chem and all my other subjects for next year in terms of writing notes
in yr 11 i did bio as a 3/4 and didn't do much prep before hand but did my notes as i went throughout the year
but this year Id like to start doing a bunch of question and learning content and writing notes to be prepared for this year
Now i want to hand write my notes and I would begin writing them using my textbook and other notes I have but as I learn the content when I go back to school there will be things I want to add or things Ill want to rewrite in a different way whichhh i cant really do since Im not typing them. Also I'm not sure if i should write my notes following the order of the textbook or follow the study design or follow the order of stuff we do at school.
Sorry for this confusing question but I would really appreciate any tips on how you are preparing for next year and how you are approaching notes
Thanks heaps!!

[deStudent]

The answers didn't give answers for these explain questions, so I'm not sure if what I wrote is actually correct.

Do my answers actually answer the question? http://m.imgur.com/a/NiKIw Cheers friends.

[Gogo14]

1. Really confused as to why I lost a mark for sig figs here.
http://imgur.com/Htz7jk6
2. What do u do in this question where there are no concordant titres (there is no three which lie within 0.1 ml of each other
http://imgur.com/h8Hnwwj

[sweetcheeks]

Really confused as to why I lost a mark for sig figs here.
http://imgur.com/Htz7jk6

The answer should be to 3 significant figures just like yours is. Do you happen to know how many significant figures was in the proper answer?

[Gogo14]

The answer should be to 3 significant figures just like yours is. Do you happen to know how many significant figures was in the proper answer?

Just editted my post to include another question. No I dont know the answer, but another student got the same as me and got the marks. Is this a marking error?

[sweetcheeks]

I assume it is a marking error, there should be 3 sig figures in the answer. As for your titration question, I would have just chosen the 3 closest values. Concordant values are one of those contentious areas, some people say 0.10mL and others 0.20mL difference is acceptable.