So for the Ka one I got 7.21x10-3 the first time then I went full retard and thought that the Mr for the moles would not include Na as it was only HSO4-. So I crossed out that answer and redid the calculation with the same method how many marks will I lose cause I used the wrong Mr

Reply 45

Mcgreggorrrrrrrr

13

What was the H+ concentrations q, where it asked why the pH would increase ?

Reply 46

Onisparks

10

Whet was the 1.25*10^-3 the answer for?

Original post by Edexcel Are mugs

So 1.25*10^-3
100cm^3 at 1 mol
Mole fraction 0.352
0.408 for concentration
Just a frw

Reply 47

Onisparks

10

You also need to talk about washing it with distilled water and adding that to the volumetric flask as well as using a funnel.

Original post by Ninja8004

For standard solution
Step 1 - Weigh the sample and weighing boat/bottle and then weigh the weighing boat and work out the difference
Step 2 - Disolve in distilled water and use a glass rod to mix
Step 3 - Transfer to a 250cm^3 volumetric flask and invert

Reply 48

Nraza

11

how did people work out the temp, I got a gradient of -0.01V... but then got a temp of like 5899😂 how did you work it out?

Reply 49

LORD_LFC_5

13

m (gradient)= T x - 4.321x10-3, so you rearrange for T and shouldve got like 302K

Original post by Nraza

how did people work out the temp, I got a gradient of -0.01V... but then got a temp of like 5899😂 how did you work it out?

Reply 50

Nraza

11

what did people put for the dehydration of ethene MC one? because i swear they all seemed logical lol!

Reply 51

Charley T

6

MCQs I can remember. NOTE: This doesn’t imply answer (or even question I remember) is correct:
1. Which substance can be recrystallised: benzoic acid
2. Something about cell voltage (zinc copper?) +1.1V (think may be I misread)
3. H bonds in DNA: Guanine to cytosine, 3 bonds
4. Which one isn’t an electrical conductor: bonded electrons in metal (other options were a molten ionic compound, graphite & lone pairs of e- on O in water. Bonded e- in a metal was a more obvious choice to me).
5. Which has greatest first ionisation energy: He (not H sorry, typo)
6. Drying agent: CaSO4
7. nSO3: 0.4 or was it 0.6? (incorrect anyway, confused myself & gave up...)
8. Something about enthalpy of NH3 + O2: -680 ish (assumed more bonds broken = less exothermic but not convinced)
9. Question on acylation of benzene: can draw mech in 30s, stupidly opted to f*** about & give up...
10. Which of the following statements is incorrect about hydrogen halides HCl to HI: picked boiling points decrease down group
11. Give species of aspartic acid at pH 12: the one with 2 x COO- & no +NH3
13: Something about which species formed by a reaction with acidified potassium dichromate: picked the ketone
14. Table of reaction results with NaHSO4 (?) & Tollens then 4 options (alcohol, aldehyde, ketone, carbox. acid): picked the alcohol
15. Moles of H2A in reaction with NaOH (or other way around): 100cm3 of 1.0 mol dm-3

(edited 4 years ago)

Reply 52

Nraza

11

See I did do that but then I got confused with the
+c bit i thought you had to take away the E°cell
and then the weird ln (Zn2+/Cu2+) thing.. overcomplicated rearranging it :/

Original post by LORD_LFC_5

m (gradient)= T x - 4.321x10-3, so you rearrange for T and shouldve got like 302K

Reply 53

LORD_LFC_5

13

yh, should've left the +c part, sorry... it's okay pretty sure that question was designed as an overcomplicated qn and confuse people so not many people would've got it anyway, you'll be fine dw

Original post by Nraza

See I did do that but then I got confused with the
+c bit i thought you had to take away the E°cell
and then the weird ln (Zn2+/Cu2+) thing.. overcomplicated rearranging it :/

Reply 54

blueoreo

3

For the Ka question I did it right but I didn’t do H+^2 I just did the HA = A- so I got 0.19 to 2DP. I’m thinking I got 4/6 for this but so annoyed.

Reply 55

Edexcel Are mugs

9

It’s not hydrogen it’s helium

Original post by Charley T

MCQs I can remember:
1. Which substance can be recrystallised: benzoic acid
2. Something about cell voltage (zinc copper?) +1.1V (think may be I misread)
3. H bonds in DNA: Guanine to cytosine, 3 bonds
4. Which one isn’t an electrical conductor: bonded electrons in metal
5. Which has greatest first ionisation energy: H
6. Drying agent: CaSO4
7. nSO3: 0.4 or was it 0.6? (incorrect anyway, confused myself & gave up...)
8. Something about enthalpy of NH3 + O2: -680 ish (assumed more bonds broken = less exothermic but not convinced)
9. Question on acylation of benzene: can draw mech in 30s, stupidly opted to f*** about & give up...
10. Which of the following statements is incorrect about hydrogen halides HCl to HI: picked boiling points decrease down group

Reply 56

LORD_LFC_5

13

most of them i got apart from, 4, which i can't remember the answer for. 5 was defo He not H and 8 was definitely -1340kJmol-1

Original post by Charley T

MCQs I can remember:
1. Which substance can be recrystallised: benzoic acid
2. Something about cell voltage (zinc copper?) +1.1V (think may be I misread)
3. H bonds in DNA: Guanine to cytosine, 3 bonds
4. Which one isn’t an electrical conductor: bonded electrons in metal
5. Which has greatest first ionisation energy: H
6. Drying agent: CaSO4
7. nSO3: 0.4 or was it 0.6? (incorrect anyway, confused myself & gave up...)
8. Something about enthalpy of NH3 + O2: -680 ish (assumed more bonds broken = less exothermic but not convinced)
9. Question on acylation of benzene: can draw mech in 30s, stupidly opted to f*** about & give up...
10. Which of the following statements is incorrect about hydrogen halides HCl to HI: picked boiling points decrease down group

Reply 57

Edexcel Are mugs

9

also lone pairs in water don’t conduct

Original post by Charley T

MCQs I can remember:
1. Which substance can be recrystallised: benzoic acid
2. Something about cell voltage (zinc copper?) +1.1V (think may be I misread)
3. H bonds in DNA: Guanine to cytosine, 3 bonds
4. Which one isn’t an electrical conductor: bonded electrons in metal
5. Which has greatest first ionisation energy: H
6. Drying agent: CaSO4
7. nSO3: 0.4 or was it 0.6? (incorrect anyway, confused myself & gave up...)
8. Something about enthalpy of NH3 + O2: -680 ish (assumed more bonds broken = less exothermic but not convinced)
9. Question on acylation of benzene: can draw mech in 30s, stupidly opted to f*** about & give up...
10. Which of the following statements is incorrect about hydrogen halides HCl to HI: picked boiling points decrease down group

Reply 58

jakehill_01

8

He has highest first ionisation energy

Original post by Charley T

MCQs I can remember:
1. Which substance can be recrystallised: benzoic acid
2. Something about cell voltage (zinc copper?) +1.1V (think may be I misread)
3. H bonds in DNA: Guanine to cytosine, 3 bonds
4. Which one isn’t an electrical conductor: bonded electrons in metal
5. Which has greatest first ionisation energy: H
6. Drying agent: CaSO4
7. nSO3: 0.4 or was it 0.6? (incorrect anyway, confused myself & gave up...)
8. Something about enthalpy of NH3 + O2: -680 ish (assumed more bonds broken = less exothermic but not convinced)
9. Question on acylation of benzene: can draw mech in 30s, stupidly opted to f*** about & give up...
10. Which of the following statements is incorrect about hydrogen halides HCl to HI: picked boiling points decrease down group