AQA AS Chemistry UNIT 1: ISA Revision

how hard was the biology one? and your allowed to know that its a titration but nothing more, thats all i know anyway hehe

jesus why can't i do this question, someone please give it a shot hahaha i think its really easy just had a head fail

7 The table below shows some information about three sulfamic acid based de-scalers.
De-scaler
Sulfamic acid content



Dip-to-Clean
3.5 % by mass

0.7 £Price/100 cm3

Clean It
1.5 % by mass
0.40 £Price/100 cm3

Lose that Scale
9.8 % by mass
2.20 Price/100 cm3

Use the data in the table to determine which de-scaler offers the best value for money, based on sulfamic acid content.

im assuming its just a basic percentage question its from the 2007 specimen chem3t paper if you can't understand what I'm asking Q7

Also if anyone looks at question 5 could someone tell me how to do it? i know its hard to without actual values

do we need to know anything on unit 2?

Gah was bare hard! 26/30 (plus full marks in your practicals) only equals 48/60 UMS! I fear i've only got about 26 :s

R88ney please do you have any past electricity physics and biology ISA papers, or the 2011 chem ones for titration? If you have anything for AS at all ill be grateful!!

Original post? Mine too

My ISA test is next week :/ What stuff are we supposed to revise / know about? my teacher has barely mentioned anything?

Calculations obviously, what about the written part...is it just knowing about safety/how to improve accuracy??

Thanks

how did your ISA go ? ive got it next week any tips?

Sorry mate, we can't divulnge any information regarding the REAL ISA PAPER. However, we can only help you with your revision/ any help required answering a PAST ISA question, or a ISA question in general.

I got 40/50 on the ISA...

could I still get an A overall in chem AS??

(I reckon for unit one exam I've got a B and an A for unit 2)

I'm sorry if it's a stupid question... just didn't want to lose 10 whole marks

That's not a stupid question AT ALL.
You would need to know the exact UMS score to be 100% sure.
Nonetheless, we can still get a good approximate:
Unit 1: 80/100 UMS = A
Unit 2: 110/140 UMS= A
Unit 3: 36/60 UMS= C - 40/50 RAW Marks. (Basing it on last year's Raw marks to UMS conversion)
Total (80+110+36)= 226/300 = B -> You would need to get a superb UMS score in Unit 2 (about 124-134), taking that into consideration, you most likely have gotten a B)
= 240/300 UMS= A
Many students from my school have who gotten an A/B in unit 1 seem to have done worser in unit 2 with B/C's (last year's students anyway), so If your dead certain that you smacked the unit 2 test then you might have gotten an A, but B is a good approximate to make.

ISA's always lower people's grades, stupid grade boundaries!

Thank you for taking the time to work all that out !

You do 2 ISAs in AS and only one of them is put through right?
Yes
so if I got a B in the unit 2 ISA then that could be put forward and I'd be more likely to get an A overall...
Yes

Do you reckon that would be enough to give me a high enough mark at AS so that in A2 I can try to get an A*?
As long as you get an A overall in AS, then you have the same chance as everybody else to get an A* in A2.
You have to get 270/300 (90UMS Unit 3: A*, 130 UMS Unit 4: A*, 50 UMS ISA: A-> or anything equivalent), and at minimum 240/300 in AS- Grade: A. Which means, you get an A* as an A-level overall grade (same rule applies for biology, physics, maths and pretty much all A-level subjects).

Usually People who get like 290/300 UMS in AS, are almost guaranteed to get an A as a A-Level overall grade (only need 190/300= High C in A2 to get A Overall), but don't stand any advantage with there AS grade in having a higher chance of getting an A* (as you still have to get 270/300).