sketch a graph to show how the value of the rate constant varies with temperature. I drew a curve but in the mark scheme its not allowed. (jan08 q6b) :confused:

Reply 784

lamalas600

1

Original post by shuaib786

When adding H+ ions into a buffer solution, the equilibrium shifts to the right hand side.
When adding OH- ions into a buffer solution, the equilibrium shifts to the left hand side.

Please can someone correct me here or confirm it right.

Opposite way round, when adding OH- shifts to the right, as it reacts with the acid producing more reactants

Reply 785

callmenighthawk

2

Original post by sconter

makes no sense, if it increases exponentially a graph would be a curve

if the graph were a natural log graph then it would be a straight line.

two possible things :

the axis on the temperature scale isn't uniform, meaning a straight line would indicate exponential increase
the graph is a natural log graph

temperature does increase exponentially with k

Reply 786

Doctor.

OP

12

Original post by g00d4u

what does this mean???
"increases (exponentially) allow straight line but not curve" help
its about how rate constant varies with temperature

Original post by sconter

makes no sense, if it increases exponentially a graph would be a curve

That's what I I was thinking lol

Original post by g00d4u

sketch a graph to show how the value of the rate constant varies with temperature. I drew a curve but in the mark scheme its not allowed. (jan08 q6b) :confused:

It's a curve, anything that suggests otherwise is stupid!

Reply 787

shuaib786

2

Original post by lamalas600

Opposite way round, when adding OH- shifts to the right, as it reacts with the acid producing more reactants

lol, so they both shift to the right then???

Reply 788

lamalas600

1

Original post by shuaib786

lol, so they both shift to the right then???

When adding H+ if shifts to the left (reacts with A-) producing more product

Reply 789

shuaib786

2

Original post by lamalas600

When adding H+ if shifts to the left (reacts with A-) producing more product

Im kinda confused, explain question 3 e) from jan 2012??

Reply 790

small'un

Original post by shuaib786

When adding H+ ions into a buffer solution, the equilibrium shifts to the right hand side.
When adding OH- ions into a buffer solution, the equilibrium shifts to the left hand side.

Please can someone correct me here or confirm it right.

when adding either H+ or OH-, equilibrium shifts to the right

(when you have an basic buffer: weak base and salt when strong acid added
NH3 + H2SO4 >< NH4+ + HSO4- if you add OH- to that, it reacts with the NH4+ reducing the concentration of that, so equilibrium displaces to the right, if that makes sense?)

Dont know if my equations are correct but i hope the principle helps

Reply 791

a_patel93

Original post by Bubbles94

CHEM5 will be alright i think.. but CHEM4 was terrible...
be careful about resitting CHEM4.. its so difficult to revise alongside CHEM5.. and if you put too much attention on CHEM4.. you could mess up CHEM5, and we only get one shot at CHEM5 :/

i agree with that. havent touched chem5 haha. i flopped chem 4 in jan, got me 70% chem5 is impossible for me. i got a solid E in the jan 12 paper chem 5 practise LOOOOOL! with UMS conversions.. :s-smilie:

Reply 792

Doctor.

OP

12

Original post by small'un

when adding either H+ or OH-, equilibrium shifts to the right

(when you have an basic buffer: weak base and salt when strong acid added
NH3 + H2SO4 >< NH4+ + HSO4- if you add OH- to that, it reacts with the NH4+ reducing the concentration of that, so equilibrium displaces to the right, if that makes sense?)

Dont know if my equations are correct but i hope the principle helps

Your equations make sense :smile:

Reply 793

lamalas600

1

Original post by shuaib786

Im kinda confused, explain question 3 e) from jan 2012??

I'm wrong sorry made a mistake, How do i access jan 2012 :smile:

?

Reply 794

username911781

Can some one explain the marking points when H+ or OH- ions are added to a buffer solution please. (I.e. when they ask for the qualitative description with eqm stuff in the mark scheme).

Reply 795

shuaib786

2

Original post by lamalas600

I'm wrong sorry made a mistake, How do i access jan 2012 :smile:

?

here 3 e) plzzz???

AQA-CHEM4-QP-Jan12 (2).pdf846.0KB

AQA-CHEM4-W-MS-Jan12.pdf207.7KB

Reply 796

shuaib786

2

Original post by small'un

when adding either H+ or OH-, equilibrium shifts to the right

(when you have an basic buffer: weak base and salt when strong acid added
NH3 + H2SO4 >< NH4+ + HSO4- if you add OH- to that, it reacts with the NH4+ reducing the concentration of that, so equilibrium displaces to the right, if that makes sense?)

Dont know if my equations are correct but i hope the principle helps

Thanks and thanks for the example to.

Reply 797

small'un

Original post by kontemptXD

Can some one explain the marking points when H+ or OH- ions are added to a buffer solution please. (I.e. when they ask for the qualitative description with eqm stuff in the mark scheme).

If adding OH- it reacts with the acid formed [conjugate base] (whatever is given in the question, it will usually tell you to write the equation before)

If adding H+, it reacts with the base formed [conjugate acid] (same for this)

So the equilibrium displaces to the right