What'd people get for the pH buffer ratio question (I got 36/5 I've got no idea)
And what'd people get for the % iron in the alloy (I think mine was between 17 and 20)

Reply 25

AA55

Original post by LOu0reo

What'd people get for the pH buffer ratio question (I got 36/5 I've got no idea)
And what'd people get for the % iron in the alloy (I think mine was between 17 and 20)

i think i got around 18 but wht did u get for enthalpy of c-h bond

Reply 26

choco1234

Original post by LOu0reo

What'd people get for the pH buffer ratio question (I got 36/5 I've got no idea)
And what'd people get for the % iron in the alloy (I think mine was between 17 and 20)

i got 8% for the iron :/ how did u do it?

Reply 27

choco1234

Original post by AA55

i think i got around 18 but wht did u get for enthalpy of c-h bond

i got like +341 i think

Reply 28

bw8376

What topics were the longer questions on?
Any predictions for what will come up next?

Reply 29

smiggs

Same

Original post by choco1234

i got 7.13...

Reply 30

choco1234

did people say that the titre increases when using hcl instead of sulfuric acid?

Reply 31

AA55

Original post by choco1234

did people say that the titre increases when using hcl instead of sulfuric acid?

yes thats what i wrote but i was unsure what ecell value to use chlorine or H+

Reply 32

choco1234

Original post by AA55

yes thats what i wrote but i was unsure what ecell value to use chlorine or H+

me too - i used the cl but not sure if its right

Reply 33

AA55

Original post by bw8376

What topics were the longer questions on?
Any predictions for what will come up next?

what came up:
electrochemical cells
enzymes
buffers, pH
group 2
titrations
amino acids

Reply 34

AA55

Original post by choco1234

me too - i used the cl but not sure if its right

i forgot which one i chose but that whole question i hated i hate electro chemical cells sm

Reply 35

choco1234

what values did everyone get/what did everyone do for the yield and conc of naoh question?

Reply 36

amythestx

Original post by choco1234

what values did everyone get/what did everyone do for the yield and conc of naoh question?

for yield i think i got 80% i did moles of the product whatever it was over moles of the reactant
for the naoh one i cant remember but something like 0.02? u had to use kw = conc h+ x conc oh-

Reply 37

choco1234

do you guys think grade boundaries will be lower considering paper was defo harder than past papers? like 75 for A* instead of like 85 or something?

Reply 38

choco1234

Original post by amythestx

for yield i think i got 80% i did moles of the product whatever it was over moles of the reactant
for the naoh one i cant remember but something like 0.02? u had to use kw = conc h+ x conc oh-

did same thing! i got 80% and 0.288 for conc cos you use the ph to work out h+ conc and then do 10^-14 divided by h+ conc i think!

Reply 39

gwall3r2005

Original post by Awesomehole3333

Not bad test. Struggled with pH ratio question though

I think it was using the healthy blood pH and the salt:acid ratio to calculate the Ka of the acid.
Then use this Ka in a separate equation for the acidosis blood and that pH to calculate the salt:acid ratio :smile: