AQA AS level maths questions

Given the increase in the amount of mathsquestions in the new AQA AS level specification, does anyone havemore complex maths questions related to the exam? i.e:

•

ideal gas equation

•

equilibrium constant questions - I've heard about quadratic Kcquestions, but have been unable to find any

•

advanced titrationquestions

•

harder Hess cycle and enthalpy questions

•

etc.

Any sources would be greatly appreciated,many thanks.

Reply 1

Ano123

Original post by alexw2150

Given the increase in the amount of mathsquestions in the new AQA AS level specification, does anyone havemore complex maths questions related to the exam? i.e:

•

ideal gas equation

•

equilibrium constant questions - I've heard about quadratic Kcquestions, but have been unable to find any

•

advanced titrationquestions

•

harder Hess cycle and enthalpy questions

•

etc.

Any sources would be greatly appreciated,many thanks.

Kc for the equilibrium below is 10 at 450 K. If 1 mole of the ester is mixed with 5 moles of water and the mixture allowed to reach equilibrium, how many moles of each species will be present at equilibrium?
HCOOCH3(g) + H2O(g) ⇌ HCOOH(g) + CH3OH(g)
Have a go at this Q.

Reply 2

alexw2150

Original post by Ano123

Would it be:

HCOOCH3: 0.024 moles

H2O: 4.024 moles

HCOOH : 0.976 moles

CH3OH: 0.976 moles

Reply 3

Ano123

Original post by alexw2150

Would it be:

HCOOCH3: 0.024 moles

H2O: 4.024 moles

HCOOH : 0.976 moles

CH3OH: 0.976 moles

Looks good. That's what I got. Ive got a hard redox one of you want to have a go at it.

Reply 4

alexw2150

Original post by Ano123

Looks good. That's what I got. Ive got a hard redox one of you want to have a go at it.

If possible, that would be great

Reply 5

Ano123

Original post by alexw2150

If possible, that would be great

A sample of solid ethanedioic acid (

\text{H}_2\text{C}_2\text{O}_4 \cdot 2\text{H}_2\text{O}

) has been contaminated with potassium ethanedioate (

\text{K}_2\text{C}_2\text{O}_4 \cdot x \text{H}_2\text{O}

). A 1.780 g sample of this mixture was made up to a 250 cm3 solution with distilled water. A 25 cm3 sample was titrated against 0.100 mol dm-3 sodium hydroxide, requiring 17.35 cm3. Another 25 cm3 sample was acidified with sulphuric acid and titrated against 0.0200 mol dm-3

\text{KMnO}_4

solution, requiring 24.85 cm3. Calculate

x

\text{C}_2\text{O}_4^{2-}

→

2\text{CO}_2 + 2\text{e}^-

.
May the Lord have mercy on your soul.
In all seriousness if you can do this you can do any question that there will be in an exam on titrations. (I advise you to write out the half equations first)

(edited 7 years ago)

Reply 6

Sniperdon227

Original post by alexw2150

Would it be:

HCOOCH3: 0.024 moles

H2O: 4.024 moles

HCOOH : 0.976 moles

CH3OH: 0.976 moles

Assuming you do alevel maths, did you not end up with a quadratic equation and therefore two values of x because I did x= 0.9763 and 5.69 from this how did you determine to choose 0.9763, and then obviously subtracting this from 1 and 5 respectively

(edited 7 years ago)

Reply 7

Sniperdon227

Cant do the ethandioic acid question ive got the moles I just dont know what to with them, Ive got two equations H2c2o4 + Naoh balanced and Mno4- + c2o42- balanced

Reply 8

alexw2150

Original post by Sniperdon227

Yes, you get 2 values. However, As you only start with 1 mole of HCOOCH3, if the value for x is 5.69, then you would end up with a negative amount of moles of HCOOCH3. (It can be phrased that x<1)

I have yet to get round to the other question yet, I've had physics revision to do.