AQA A Level Chemistry (2420) Unit 2 10th June 2016 (Resit)

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Guys for the q on the magnesium reaction do you think flames and precipitate will be sufficient? I put white ppt at first but crossed the white out in case it was the wrong colour and talked myself out of a mark

Reply 41

arronpile

Original post by Rid123

For the pair of serioisomers of C5H10, i was confused and i put the E,Z isomers for pent-2-ene, is that correct if not what was it does anyone know?

yh i put that

Reply 42

samim_s

Original post by arronpile

wasnt it conc h2so4 because its going from an alcohol to a alkene and the condition for this was reflux

Isnt h2so4 to go from an alkene not to go to a alkene

Reply 43

samim_s

For the ispmers wpuld pent-2-ene be okay? And 2-methyl-but-2ene ?

And for magnesium would magnesium hydroxide be okay mg (oh)2?

Reply 44

arronpile

Original post by samim_s

Isnt h2so4 to go from an alkene not to go to a alkene

no h2so4 is alcohol to alkene
example hydration is from ethene to ethanol
and dehydration using h2so4 is from ethanol to ethene

Reply 45

arronpile

Original post by samim_s

For the ispmers wpuld pent-2-ene be okay? And 2-methyl-but-2ene ?

And for magnesium would magnesium hydroxide be okay mg (oh)2?

magnesium has to be mgo because its in steam if i was in water h20 then mg(oh)2 is right

Reply 46

emily1414xo

Original post by samim_s

For the ispmers wpuld pent-2-ene be okay? And 2-methyl-but-2ene ?

And for magnesium would magnesium hydroxide be okay mg (oh)2?

I put Mg(OH)2 and H2, observations as white ppt and bubbles of gas, but people seem to be getting different :s-smilie:

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Reply 47

ManOfJustTin

Original post by samim_s

For the ispmers wpuld pent-2-ene be okay? And 2-methyl-but-2ene ?

And for magnesium would magnesium hydroxide be okay mg (oh)2?

For the isomer, I think they specified stereoisomers so I think you needed to put E-Z.

Not sure about the magnesium tho sorry :s-smilie:

Reply 48

emsieMC

Original post by Medibananas

It was combustion data, so isn't that reactants-products

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yeah that's what I did because it was combustion data

Reply 49

emsieMC

Original post by arronpile

magnesium has to be mgo because its in steam if i was in water h20 then mg(oh)2 is right

Yeah

Reply 50

emsieMC

Original post by davgen7

I think it has to be white solid

Reply 51

arronpile

what are disadvantages of fermentation over hydration other than its slower process

Reply 52

Rid123

Original post by emily1414xo

I put Mg(OH)2 and H2, observations as white ppt and bubbles of gas, but people seem to be getting different :s-smilie:

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I think it was mg and steam which i think is mgo and h2 giving bright white flame and white SOLID(not ppt)
Mg(oh)2 forms when mg reacts with cold water

Reply 53

Mattk1997

Original post by Rid123

For the pair of serioisomers of C5H10, i was confused and i put the E,Z isomers for pent-2-ene, is that correct if not what was it does anyone know?

I put the same

Reply 54

I like cows

Original post by emsieMC

yeah that's what I did because it was combustion data

Wasn't it formation

Reply 55

Tribex21

Original post by I like cows

Wasn't it formation

It said work out enthalpy of formation with combustion data

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Reply 56

I like cows

Original post by Medibananas

It said work out enthalpy of formation with combustion data

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So would that be reactants-products?

Reply 57

2015-atif

I wrote about titrating the AgCl with NH3, and then to see how much NH3 reacted would that be right?

Original post by I like cows

I'm pretty sure weighing the precipitate is right, not using a colorimeter.

Reply 58

SACREDHT

I also thought it should be reactants - products as i was taught to look at what time of enthalpy DATA you're actually given, and the data was combustion