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Edexcel Chemistry A2 Unit 5 ~ Wednesday 19th June 2013 (Now Closed)

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Reply 1900

orange94

Is chem 5 a replacement paper or was that only maths for edexcel

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Reply 1901

Weaselmoose

Original post by posthumus

Ah okay I see how it works ! :smile:

So if I have volume of 32.32313242

uncertainty is 32.000000005 ??? :tongue:

Uncertainty of a burette is +-0.05, so percentage uncertainty with one reading is ( (0.05 x 2) / 32.32414242 ) x100 =0.309 %(3sf)

Reply 1902

AS01

Original post by Weaselmoose

Uncertainty of a burette is +-0.05, so percentage uncertainty with one reading is ( (0.05 x 2) / 32.32414242 ) x100 =0.309 %(3sf)

isnt it 0.005?

Reply 1903

posthumus

Original post by Weaselmoose

Uncertainty of a burette is +-0.05, so percentage uncertainty with one reading is ( (0.05 x 2) / 32.32414242 ) x100 =0.309 %(3sf)

Oh I made an exagguration here :frown:

What if there's a burette which gave me such an accurate volume, then wouldn't it's uncertainty be +-00.000000005

Reply 1904

Weaselmoose

Original post by AS01

isnt it 0.005?

All the burettes I've ever used have been to the nearest 0.1 which means that their uncertainty is +-0.05

Reply 1905

AS01

Original post by Weaselmoose

All the burettes I've ever used have been to the nearest 0.1 which means that their uncertainty is +-0.05

lol yeah just realised that :colondollar:

Reply 1906

Weaselmoose

Original post by posthumus

Oh I made an exagguration here :frown:

What if there's a burette which gave me such an accurate volume, then wouldn't it's uncertainty be +-00.000000005

Haha technically yes but it's very unlikely that they'll give you one like that in the exam - calculations might be minute!

Reply 1907

posthumus

Original post by Weaselmoose

Haha technically yes but it's very unlikely that they'll give you one like that in the exam - calculations might be minute!

I see thanks :biggrin:

I should really stop getting carried away... I need to learn the basics within then next few hours ! :tongue:

Reply 1908

posthumus

Do I need to learn how to name transition metals with oxidation state less than zero?

Reply 1909

Weaselmoose

Original post by posthumus

I see thanks :biggrin:

I should really stop getting carried away... I need to learn the basics within then next few hours ! :tongue:

Haha same but my brain feels so frazzled!

Reply 1910

Mallika

Does nitrous acid react with HCl to produce a diazo compound with all amine groups or only those bonded to benzene?

Reply 1911

orange94

Hope the paper is super duper great in an ideal world :smile:

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Reply 1912

iwantopas19

I feel like I dont know a single thing... :/

Reply 1913

orange94

Original post by iwantopas19

I feel like I dont know a single thing... :/

Go to bed relax the paper in the morn will jigg your memory

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Reply 1914

iwantopas19

Original post by orange94

Go to bed relax the paper in the morn will jigg your memory

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no time. only 3 hours left..and i still have to learn.. :/ I hate chem.

Reply 1915

posthumus

Original post by iwantopas19

no time. only 3 hours left..and i still have to learn.. :/ I hate chem.

Same here

good luck!

Reply 1916

iwantopas19

Original post by posthumus

Same here

good luck!

thank you ! :smile:

BEST of luck :smile:

Reply 1917

Gnome :)

Hooray pre-exam insomnia -_-

Lying in bed watching Khan academy videos instead haha...
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Reply 1918

randyaloul

I can't sleep at all and I have to be up by 4 and a half hours ;_;
Can someone help clear my doubts regarding percentage errors? For example if they said a thermometer to the nearest 0.1, will the accuracy be +\- 0.05?

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Reply 1919

posthumus

Original post by randyaloul

If you would get a result of lets say 14.3 for example accuracy will be 0.5

0.05 is for a burette.... because you could get a reading of 24.94 for example