Edexcel IGCSE Chemistry 18th May/June 2017 Thread

what did people get for the compounds that went through the filter paper? I got water and magnesium sulfate but other people are saying that sulfuric acid went through the filter paper.

yeah I said water and mgso4 too

Reply 121

anniewannie

1

I said sulphuric acid

Reply 122

Hlwilson2000

Original post by comu

what did you guys put for the last question?

What was this question on?

Reply 123

BerylTheBird

5

Original post by Darwinion

Don't think so. If you put 7 as final answer you score full marks anyway even without showing any working. You always do on the marks schemes I've seen.

*sighs* I'm not too sure about that Astatine ionic equation too. What did u get ?

(edited 6 years ago)

Reply 124

Darwinion

12

I said Water and MgSO4 as well.... but I very nearly did put sulfuric acid as that would be present if the acid was in excess and all the magnesium reacted. But the question didn't say that anything was in excess either way.

If that magnesium was in excess you'd have filtered that out already and it wouldn't be present in the filtrate. So I went with that route.

It was a 2 mark question... and it may be that it's one of those "any 2 from... 3 options" as they are theoretically both correct.

(edited 6 years ago)

Reply 125

comu

6

Original post by Hlwilson2000

What was this question on?

why does rate increase with temp one other reason than the one they gave you

Reply 126

weirdperson7878

1

why was

Original post by anniewannie

I said sulphuric acid

why would it be sulfuric acid?

Reply 127

Darwinion

12

Original post by weirdperson7878

why was

why would it be sulfuric acid?

If acid was in excess and all the Mg had reacted then there would be acid left over. But the question didn't say that any of the reactants were in excess or gave any indications of masses/volumes.

Reply 128

ITSJDOG

Paper was quite confusing sometimes, anyways does anyone have an idea as to what the topics will come up in the second paper?

Posted from TSR Mobile

Reply 129

JJ16

3

Original post by daniel185

My answer was that you should use the glass rod to feel if crystals have been formed - wasn't confident with the answer though

If crystals form, it's to know that the solution is saturated, because the rod is colder than the hot solution, so crystals form on it.

Reply 130

JJ16

3

Original post by comu

why does rate increase with temp one other reason than the one they gave you

Higher percentage have energy > Ea, so there are more successful collisions with sufficient energy.

Reply 131

Darwinion

12

Original post by JJ16

Higher percentage have energy > Ea, so there are more successful collisions with sufficient energy.

Yeah I mentioned increase in kinetic energy as temp.increased... so the collisions are more likely to be over the activation energy. Not sure I explained it well enough to get all 3 marks though, as I literally scrawled it in the last 2 mins. haha

Reply 132

BerylTheBird

5

What was all about that question with the energy graph and u had to draw a line and label the energies or somthin' ?

Reply 133

DavoGCSE

3

Think that was overall a good paper, I reckon I got around 110/120, these are all the ones (that I can remember) that I'm not sure about, can someone help me out and let me know if my answers are correct or if not, what the right answers are:

Questions I wasn't sure about and my answers:
1. Why was the solution heated up - to evaporate some of the water to form crystals
2. Why did she dip the rod in the solution - to check if crystals were forming so she would know when to take it off the heat
3. What were the two compounds (both questions like this, one for sulfate test and one for salt [after being filtered]) - Iron hydroxide + sodium sulfate and H20 + MgSO4
4. Why was the HCl added - to remove impurities/contamination from chloride ions
5. What colour is NH4Cl as a solid and solution - C (white and colourless)
6. Why is the iron ore-iron reaction a redox one - Fe is losing oxygen so is being reduced (oxidising agent) and C is gaining oxygen so being oxidised (reducing agent)
7. Why was the iron powder rather than solid - surface area blah blah
8. Why was the iron mixes with water - because it couldnt react on its own with the oxygen air so the water allows it to react with oxygen, as if providing a surface for the reaction to take place on (pretty much just blagged)

Also, I'm pretty sure the calculation answers were x=7, 22.2% and 9kg

Reply 134

Catlover0161

9

Yo anyone have unofficial mark scheme please? :P

Reply 135

Jimmyfox

2

Original post by DavoGCSE

Think that was overall a good paper, I reckon I got around 110/120, these are all the ones (that I can remember) that I'm not sure about, can someone help me out and let me know if my answers are correct or if not, what the right answers are:

Questions I wasn't sure about and my answers:
1. Why was the solution heated up - to evaporate some of the water to form crystals
2. Why did she dip the rod in the solution - to check if crystals were forming so she would know when to take it off the heat
3. What were the two compounds (both questions like this, one for sulfate test and one for salt [after being filtered]) - Iron hydroxide + sodium sulfate and H20 + MgSO4
4. Why was the HCl added - to remove impurities/contamination from chloride ions
5. What colour is NH4Cl as a solid and solution - C (white and colourless)
6. Why is the iron ore-iron reaction a redox one - Fe is losing oxygen so is being reduced (oxidising agent) and C is gaining oxygen so being oxidised (reducing agent)
7. Why was the iron powder rather than solid - surface area blah blah
8. Why was the iron mixes with water - because it couldnt react on its own with the oxygen air so the water allows it to react with oxygen, as if providing a surface for the reaction to take place on (pretty much just blagged)

Also, I'm pretty sure the calculation answers were x=7, 22.2% and 9kg

Do you think if I put 7.15 I would lose a mark?

Reply 136

Jimmyfox

2

Would I lose a mark for the Moles question if I put 7.15?

Reply 137

Tatsien

13

Hey, about the last question I'm pretty sure the other reason is because it was an endothermic reaction, since bonds are broken, so more energy can be absorbed from its surroundings, breaking the bonds easier, therefore having a faster rate if reaction.

Reply 138

Darwinion

12

For the iron mixing in the water... I just said that water was needed for the reaction to take place. I couldn't think of anything more technical to say about it. And it was only a 1 mark question. Would that be enough to get the mark?