AS Chemistry- helping each other out!

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Reply 1940

samb1234

Original post by TheonlyMrsHolmes

Does anybody know what 32 marks in the AS edexcel chemistry controlled assessment is? Is it a C?

I think that would be yes. I know that a is 37 so I reckon b is probably 34ish

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Reply 1941

TheonlyMrsHolmes

Original post by samb1234

I think that would be yes. I know that a is 37 so I reckon b is probably 34ish

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Oh well, whats done is done, I found the experience painful, I just cannot to practicals. Thankyou for replying!

Reply 1942

samb1234

Original post by TheonlyMrsHolmes

Oh well, whats done is done, I found the experience painful, I just cannot to practicals. Thankyou for replying!

Any of the practicals in particular that didnt go so well?

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Reply 1943

TheonlyMrsHolmes

Original post by samb1234

Any of the practicals in particular that didnt go so well?

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My titration one but I suspected that since I was holding my thumb under the glass pipette to stop the HCL dripping out :rolleyes:

and my non-organic. I lost 4 marks in both :eek:

AQA please add me

Ocr isa quantative; titrations? Please help

Reply 1946

ajsullivan

Hey all

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Alex

Reply 1947

alevels2k15

The first five successive ionization energies of an element, X, are shown in the tablebelow.

Ionization energy: first second third fourth fifth
Value/ kJ mol–1 590 1100 4900 6500 8100

Which ion is X most likely to form when it reacts with chlorine?
A X+
B X2+
C X3+
D X4+

HELP PLEASE! :frown:

(edited 9 years ago)

Reply 1948

frozo123

Original post by alevels2k15

I'm assuming it's B because there's a huge jump between the second and third ionisation energy.

Reply 1949

alevels2k15

Original post by frozo123

I'm assuming it's B because there's a huge jump between the second and third ionisation energy.

Yeah! the answer is B :smile:

BUT how?
i dont understand how to go about answering this question :frown:

Reply 1950

frozo123

Original post by alevels2k15

Yeah! the answer is B :smile:

BUT how?
i dont understand how to go about answering this question :frown:

well what do you know about ionisation energies atm?

Reply 1951

C0balt

Original post by alevels2k15

Yeah! the answer is B :smile:

BUT how?
i dont understand how to go about answering this question :frown:

When removing an electron from a different shell there is a big jump in ionisation energy because
- there is less shielding as there is one less full shell
- ionic radius is much smaller, shorter distance between the outermost electron and the nucleus
(- higher proton to electron ratio)
and so the attraction between the outermost electron and the nucleus is much bigger which means a lot of energy is needed to remove the electron.

In this example there is a big jump between 2nd and 3rd ionisation energy, so you would know that it is a group 2 element as there are two electrons in outer shell of a group 2 metal. Group 2 metals form 2+ ions when it reacts with chlorine.

Similarly if the jump is between 1st and 2nd IE the element is in group 1 etc.

Reply 1952

grapes12

Original post by Connor_leigh

Yeah thats what my one was on aswell. What other lessons do you do? Any other ones with ISA's i can help with?

I do chemistry, biology, English language and philosophy. I just did the practical for my resit ISA in biology where we had to paint leeks with clear nail varnish and use selotape to peel off the varnish. Then put it on a slide and count how many cells are in a row in one field of view. The practical was easy but plants are my worst part in Biology so if you know what I could revise that would be great

Reply 1953

grapes12

AQA, and yourself?
Does anyone know where I could find good revision notes on the biology ISA?

Reply 1954

username1533709

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Help.I haven't really done equilibriuma in my school,but how do I answer this question?

(edited 9 years ago)

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Reply 1955

frozo123

Original post by Kadak

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Help.I haven't really done equilibriuma in my school,but how do I answer this question?

The rate of the forward reaction is equal to the rate of the backwards reaction, therefore the concentrations of them gases remain the same basically

(edited 9 years ago)

Reply 1956

grapes12

All subjects are AQA except philosophy which is OCR

Reply 1957

Mamoona231

Anyone doing Bio or chem aqa empa ? :frown:

Reply 1958

lyricalvibe

Original post by grapes12

All subjects are AQA except philosophy which is OCR

My condolences :frown:

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Reply 1959

vuvuzela

Have a couple of questions if you could;

1) what is the significance of the alkaki being in excess when reacting with copper chloride?
2) when calcium and water react, why does the hydroxide solid not form immediately, is it because the hydroxide is only slightly soluble?

Thanks

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