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Edexcel gcse chemistry- how did you find it?

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0.7 - 0.42 to get 0.28 (mass of oxygen)

0.28 / 16 = 0.0175 (O)
0.42 / 24 = 0.0175 (Mg)
Then divide each by the smallest (but since they're the same just divide by themselves)
0.0175 / 0.0175 = 1 (O)
0.0175 / 0.0175 = 1 (Mg)
Ratio is therefore 1:1
So it's therefore MgO

yasss but how did you describe the experiment and stuff?

Reply 41

Penguin_S

I wrote 1/1837 and I think that's right but they will accept 1/2000 as well

Posted from TSR Mobile

Reply 42

glowanti

Original post by Heardmanator

For the last one I talked about heating magnesium to get MgO and then did the empirical formula but because Oxygen is diatomic and they were all in the same ratio, you just had to multiply all of them by two to get 2Mg + O2 -> 2MgO to get the formula for it

Reply 43

username2174765

Original post by Penguin_S

I wrote 1/1837 and I think that's right but they will accept 1/2000 as well

Posted from TSR Mobile

anything below 1/5000 they will accept

Reply 44

glowanti

Original post by vik_k1

I put 1/1837 as relative mass of an electron. Will I get a mark for that because apparently it's 1/2000???

Posted from TSR Mobile

I put 1/1836

Reply 45

username2174765

Original post by caitlinford3

oh???? then maybe i didn't lose 3 marks LOL

yeah because it just said 'a' experiment it didn't say like using a crucible or bell jar, like the C1 paper said when it said using "paraffin"

Reply 46

glowanti

Original post by KeziaKarunwi

yasss but how did you describe the experiment and stuff?

I know I lost marks on this bit but I said about putting the magnesium ribbon, with the measured mass, in a bell jar and then measuring the mass after it had reacted with an unknown about of oxygen, then measuring the mass of the oxidised magnesium and from this working out the mass of oxygen. I know I lost marks though and that there was other ways of doing it!

Reply 47

Heardmanator

Original post by caitlinford3

Yep I understand that it's MgO but oxygen doesn't just travel around by itself so there was O2 which meant you had to put a two in front of the MgO and the Mg to balance the equation

Reply 48

Penguin_S

I got this for the pcl3 covalent bond question but my friend said that it was pcl2...? What did you guys get?

Reply 49

KeziaKarunwi

Original post by caitlinford3

I put 1/1836

i just said negligible i hope thats okay

Reply 50

sapphire79

Original post by Penguin_S

I got this for the pcl3 covalent bond question but my friend said that it was pcl2...? What did you guys get?

I got this too :smile:

Reply 51

glowanti

Original post by Penguin_S

I got this for the pcl3 covalent bond question but my friend said that it was pcl2...? What did you guys get?

it was phosphorus trichloride, so three chlorines, so you were right

Reply 52

glowanti

Original post by chrlhyms

yeah because it just said 'a' experiment it didn't say like using a crucible or bell jar, like the C1 paper said when it said using "paraffin"

very true, I just didn't realise my experiment was legit hahaha

Reply 53

KeziaKarunwi

Original post by Penguin_S

I got this for the pcl3 covalent bond question but my friend said that it was pcl2...? What did you guys get?

that's right its pcl3 - I didn;t draw the shells because my teacher taught us they were irrelevant but okay

Reply 54

L0st45

I absolutely loved that exam! The to six markers were godsends I thought - the calculation questions were wonderful and I thought, in general, that paper was fantastic. So happy! :biggrin:

Reply 55

Fez_Shabbir

Original post by caitlinford3

Very easy, last 6 marker was weird

Easy???? :0

Reply 56

Fez_Shabbir

Is a period going down or across and what do you reckon it is for a C grade?

Reply 57

L0st45

Original post by caitlinford3

I put 1/1836

I stated it exactly how it was in the revision guide - 1/1840. I did put in brackets underneath my answer 'negligible' as well though.

Reply 58

KeziaKarunwi

Original post by Fez_Shabbir

Is a period going down or across and what do you reckon it is for a C grade?

it goes down x

Reply 59

glowanti

Original post by Heardmanator

Yep I understand that it's MgO but oxygen doesn't just travel around by itself so there was O2 which meant you had to put a two in front of the MgO and the Mg to balance the equation