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iGCSE AQA Chemistry 8402 - 14th May 2015 Post exam discussion

Post-discussion on the AQA iGCSE Chemistry Paper 1 on 14th May 2015,

Why do nanoparticles need to be used in small amounts??

If there are other threads on this exam, please let me know,
Thanks

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Reply 1

loros

Because they have a large surface area to volume ratio

Reply 2

liv1111

what did you put for the water one? i can't remember the exact question, but it was something along the lines of 'what observations are mae when ... is added to water'

Reply 3

loros

Original post by liv1111

what did you put for the water one? i can't remember the exact question, but it was something along the lines of 'what observations are mae when ... is added to water'

The one about ammonia and taps? I thought it formed a white precipitate bu im not too sure

Reply 4

ssh555

Original post by liv1111

what did you put for the water one? i can't remember the exact question, but it was something along the lines of 'what observations are mae when ... is added to water'

Which one there was once about what do you observe when it reacts with one thing i forgot what it was but magnesium gets smaller and there's effervescence. The sodium hydroxide and aluminum one was a white precipitate is formed and i wrote about what happens in excess?

(edited 8 years ago)

Reply 5

liv1111

Original post by loros

The one about ammonia and taps? I thought it formed a white precipitate bu im not too sure

yeah i put a white precipitate too :smile:

Reply 6

liv1111

Original post by ssh555

yeah i put those answers too

Reply 7

liv1111

how did you all find the aqa igcse chemistry exam?

Reply 8

kingspaniard

Original post by loros

Because they have a large surface area to volume ratio

Yes! I put that!

Reply 9

loros

Original post by liv1111

yeah i put those answers too

Is effervescence and hydrogen gas produced count or not? Damn im so worried :s-smilie:

Reply 10

JGray99

what did people put for the last question on alcohols?

Reply 11

ssh555

Original post by loros

Is effervescence and hydrogen gas produced count or not? Damn im so worried :s-smilie:

I guess so in the questions I did before that was an accepted answer so hopefully yes.

Reply 12

sunnyrays07

Original post by JGray99

what did people put for the last question on alcohols?

I put something along the lines of more carbon atoms so more forces and therefore harder to overcome

Reply 13

sunnyrays07

How did you all work out the energy change one? Did you times the joules by the moles or divide it?

Reply 14

JGray99

Original post by sunnyrays07

How did you all work out the energy change one? Did you times the joules by the moles or divide it?

I multiplied them but it was meant to be divide as it was J/mole so it was something like 198947 i think

Reply 15

sunnyrays07

Original post by JGray99

I multiplied them but it was meant to be divide as it was J/mole so it was something like 198947 i think

I multiplied it too! But everyone divided it :frown:

What did you get for the empirical formula?

Reply 16

piggypenguin

Original post by sunnyrays07

I put something along the lines of more carbon atoms so more forces and therefore harder to overcome

I got that question completely wrong i think :frown:

i realised afterwards but it was the longer the chain is the stronger the forces between the molecules and so the more energy needed to overcome them and so the higher the boiling point but im not sure

Reply 17

carpefrickindiem

I got something like 3:1:3 for the empirical formula

Reply 18

username1955053

Original post by loros

Is effervescence and hydrogen gas produced count or not? Damn im so worried :s-smilie:

Your concept is right, however "hydrogen gas" is not something you'd see. You would have to say bubbling would be present as a result of hydrogen gas being produced because the question asked what can be seen during the reaction.