Whos ready for the June 9th exam?

[stonecold]

If that is the only two things I stuff up, then I will gladly deduct the 2 marks and couldn't care less.  But I can't afford to be throwing away marks on stupid shit like this, as it is just going to ruin my score even more...

[iffets12345]

Yeah was wondering about organic chem states. Like if you made an ester from a pure alcohol and a pure carboxylic acid, do you write the ester as (aq) cause there's now water in there? And if it's a large ester it'll be insoluble, so do you then write it as (l)?

The worst is Na2CO3, because u need to check the question as it might be in powder form OR solution....
grr.
And once they said 50ml ethanol...but I was so used to "in solution" I wrote (aq) instead of (l).....since I only really see H20 as (l)

[vexx]

i had a practice exam marked and my teacher marked a question wrong due to sig figs, and then later took a mark off another question for sig figs (used aq instead of l on two occasions >_>)..... are people actually 100% confident the sig fig rule hasn't changed?

[stonecold]

so your saying this may not apply any more.  I just learnt it.

http://vcenotes.com/forum/index.php/topic,17173.0.html

[vexx]

so your saying this may not apply any more.  I just learnt it.

http://vcenotes.com/forum/index.php/topic,17173.0.html

apparently, i'll confirm either tomorrow or friday when i see her next about itt. hopefully not!

[stonecold]

o0o0o0o  what could it have changed to...

[kyzoo]

personally id on't really see what's so hard about significant figures...

[stonecold]

There just seems to be a lot of confusion over what the rules are...

[vexx]

personally id on't really see what's so hard about significant figures...

yeah this is what i thought- where i had never gotten them wrong before but after that exam apparently you have to use (l) in so many more reactions then just 'water' as we were told >__>
i think i've learned now so it's fine but it was just a shock haha.

[m@tty]

There just seems to be a lot of confusion over what the rules are...

What, addition rules?

Addition = keep lowest number of decimal places.

Multiplication = keep lowest number of significant figures.

That's it.

EDIT:

personally id on't really see what's so hard about significant figures...

yeah this is what i thought- where i had never gotten them wrong before but after that exam apparently you have to use (l) in so many more reactions then just 'water' as we were told >__>
i think i've learned now so it's fine but it was just a shock haha.

Care to share? I am always unsure of what state is required...

[kyzoo]

And logarithm/exponential rules.

For logarithm, the result value must have the same number of decimal places as significant figures of the input value. For exponential, result value must have same number of significant figures as the decimal places on input value.

[m@tty]

Haha, okay. Thanks. Now I see what you mean, stonecold. I have never heard of these rules before...

[kyzoo]

lmao I just laerned them 10 mins ago

[stonecold]

for exponential, by input value, it means the base yeah?
don't worry.  misread it

and yeah, i suppose this stuff is trivial and easy, but only if you've had it taught to you.
all my teachers have ever told me is go to the same number of significant figures as in the question stem...

[iffets12345]

And logarithm/exponential rules.

For logarithm, the result value must have the same number of decimal places as significant figures of the input value. For exponential, result value must have same number of significant figures as the decimal places on input value.

If it requires more than one calculation, I just keep all my figures on my calc and then put the sig figs to the smallest of the numerical values provided in the question. Is that it?