Post by: Collin Li on June 05, 2008, 08:35:18 pm
Every paper has 1 mark for significant figures, and 1 mark for states. This means you can only lose 1 mark maximum, due to incorrectly doing your significant figures or states, but for those seeking to obtain these marks - don't fret. They only check one question to decide whether you pick up the mark or not. It is usually indicated by the question that says "express your answer to the appropriate number of significant figures" or "show all states." That will be the question they check for states, and they won't care about anything else, unless you state absurd amounts of significant figures.
A common concern regarding significant figures:
You only use the lowest number of significant figures out of all the numbers used in the calculations. So if a question tells you there are 0.5 grams of flowers and the question is about something else, it has no bearing on your significant figures.
Rounding
Many people ask this: do I round at each step, or do I round at the very end? Round at the very end - despite what the solutions suggest. The solutions are lazy! Round at the very end, it is the correct thing to do. I know that there are examples of the VCAA examiner reports doing it the lazy way, but the truth is that the examiner reports come out much later, and the examiners are marking from a different source as their solutions. If you save all the digits in your calculator, you can't go wrong.
Feel free to ask questions or add more here.
Post by: iamdan08 on June 05, 2008, 08:36:28 pm
Post by: cootcoot on June 07, 2008, 02:19:40 pm
Post by: Mao on June 07, 2008, 07:45:12 pm
nope =\ otherwise we'ld all be doing the stoic questions and storing the values on our calculatorscientific calculators cant store I dont think?
but no, cannot pick up anything during reading time.
Post by: polky on June 07, 2008, 08:35:08 pm
Post by: AppleXY on June 07, 2008, 08:40:33 pm
Post by: shinny on June 07, 2008, 09:17:23 pm
Post by: cara.mel on June 07, 2008, 10:38:16 pm
Post by: tiancaiyimu on June 08, 2008, 02:45:07 am
1. type value in
2. press shift
3. then the RCL button
4. lastly press any button that has the red letters above (7 options avalible, cant store in e)
Post by: Collin Li on August 12, 2008, 05:00:59 pm
well yeh ild advise all of u to learn how to store (if ur calc can do it) coz it comes in handy for keeping the exact values of numbers for each question as u should be. particularly comes in handy in those questions where u burn hydrocarbons and have to continuously restart ur calculations since u gotta find n(C), n(H), m(C) etc, then back to n(C); its not a linear calculation like the type u do in titrations at all, so yeh, storing does come quite useful
Yeah, but use Ans whenever possible for speed. Usually if you're clever you can work Ans into your next line, rather than storing (which is a bit cumbersome, IMO)
It comes in handy if you're like me and just can't be bothered with writing out 6.02E23 or other constants. =)
Yep, I do this, especially for Physics. I also use this in combination with my cheatsheet which tells me which letters on my calculator correspond to which constant. It's much safer dividing by
for those who dont know how to store values on their sci calc (casio fx-82AU) , all you have to do is this:
1. type value in
2. press shift
3. then the RCL button
4. lastly press any button that has the red letters above (7 options avalible, cant store in e)
"Type value in" will lose you one or two decimal places. I think calculators store an extra digit or two "behind the screen." What I do with this calculator is, once I have the answer I want, I press "Ans", then "=", then press SHIFT-RCL (STO) and finally picking one of the pink letters above.
Post by: pg88 on September 10, 2008, 10:55:51 pm
Question - If I use the periodic table and grab a value of that, I would have to round to that number of sig figs right (suppose that the figs there are the smallest) because my teacher was really unclear and inconsistent about that
Post by: Mao on September 11, 2008, 10:52:56 am
Post by: merlin on September 11, 2008, 09:29:05 pm
Post by: Mao on September 11, 2008, 09:42:35 pm
well, they are not suppose to
Post by: cara.mel on September 12, 2008, 02:09:14 pm
Post by: merlin on September 18, 2008, 01:00:10 pm
Quote
Significant figures and states
Every paper has 1 mark for significant figures, and 1 mark for states. This means you can only lose 1 mark maximum, due to incorrectly doing your significant figures or states, but for those seeking to obtain these marks - don't fret. They only check one question to decide whether you pick up the mark or not. It is usually indicated by the question that says "express your answer to the appropriate number of significant figures" or "show all states." That will be the question they check for states, and they won't care about anything else, unless you state absurd amounts of significant figures.
I've seen some questions that say 'u are not required to show states', so does that mean questions such as:
'write the overall reaction', mean u need to show states or else u lose 1 mark?
Post by: bec on September 18, 2008, 02:37:57 pm
A couple of questions - I've read the study design but I'm still unclear about how much we need to know about specific equations. How did everyone else interpret it?
For example, if we studied sulfuric acid will we need to know the equation that produces superphosphate, for fertiliser? Or, would we need to know the exact reactions that take place in alkaline cells, etc?
Post by: Collin Li on September 18, 2008, 06:28:52 pm
For example, if we studied sulfuric acid will we need to know the equation that produces superphosphate, for fertiliser? Or, would we need to know the exact reactions that take place in alkaline cells, etc?
Using a bit of logic, I think it is almost impossible. The question on your chemical of choice will be generic. They cannot corner you into writing the equation of sulfuric acid's role in fertiliser production, because it wouldn't be applicable to say, ethene.
As far as I know, you do not need to know the exact reactions that take place in the plethora of cells that you're presented. The textbooks aren't consistent with which ones they cover, nor does the study design specify which ones should be covered. I would focus more on fuel cells (a new dot point arose on the advantages and disadvantages of them), and if anything, the lead-acid secondary cell, perhaps.
Post by: pfftlah on October 27, 2008, 10:38:22 pm
it's doubtful they'd ask us to recall something specific about these different types of cells, right?
Post by: pinchies on October 30, 2008, 08:09:21 am
Post by: NGUB on November 06, 2008, 05:09:04 pm
Post by: shinny on November 06, 2008, 05:14:37 pm
Post by: NGUB on November 12, 2008, 07:28:25 pm
Post by: Matt The Rat on November 12, 2008, 07:34:00 pm
Post by: Collin Li on November 12, 2008, 08:01:01 pm
Can i ask sth to comfirm, so we only need to choose 1 chemical to study right??? LIKE IF I CHOOSE SULFURIC ACID, I DON'T EVEN NEED TO KNOW THE OTHER ONE RIGHT?? LIKE I DON'T EVEN NEED TO LOOK AT THEM??? OR NOT???
You only need to know 1 chemical. There will be the same one question for every chemical - it will apply be generic enough to apply to any chemical.
Post by: NGUB on November 13, 2008, 07:04:35 am
Post by: Blakhitman on January 26, 2010, 10:25:21 pm
Significant figures and states
Every paper has 1 mark for significant figures, and 1 mark for states. This means you can only lose 1 mark maximum, due to incorrectly doing your significant figures or states, but for those seeking to obtain these marks - don't fret. They only check one question to decide whether you pick up the mark or not. It is usually indicated by the question that says "express your answer to the appropriate number of significant figures" or "show all states." That will be the question they check for states, and they won't care about anything else, unless you state absurd amounts of significant figures.
OMG, is this still the same now? I am so relieved reading this, I always make a mistake with this.