# chemistry a level acidsWatch

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#1
when a strong acid dissociates,

e.g. HCl --> H(+) + Cl(-)

is Cl(-) the conjugate base then?

does Cl(-) dissociate in equal proportions to H(+)?

how is [HA] = [H(+)], if Cl(-) does dissociate in equal proportions,
wouldn't [HA] / 2 = [H(+)} instead?
0
4 weeks ago
#2
(Original post by hj!gz)
when a strong acid dissociates,

e.g. HCl --> H(+) + Cl(-)

is Cl(-) the conjugate base then?

does Cl(-) dissociate in equal proportions to H(+)?

how is [HA] = [H(+)], if Cl(-) does dissociate in equal proportions,
wouldn't [HA] / 2 = [H(+)} instead?
No, you see, according to the balanced equation: 1 mol HCl -> 1 mol (H+) + 1 mol (Cl-). Therefore, for any solution of HCl, the molar quantity of HCl is equal to that of H+, and given that the volume of the solution is constant [H+] = [HCl] using concentration = mol/volume. Equally, if you knew [Cl-] , you could determine [HCl] as their molar quantities are also equal.
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#3
okay....
yeah, that makes sense, thank you!
0
4 weeks ago
#4
Doing an access course - I understand how you get the mole/1000ml, but don't understand things like
"A glucose solution with a volume of 2.0L contains 72g glucose (C6,H12,O6). If glucose has a molar mass of 180g/mole, what is the molarity of the glucose solution?"

0
4 weeks ago
#5
1 mole of glucose weighs 180 g
How many moles weigh 72 g?

Once you find the moles, use Concentration = moles / volume
Volume must be in dm3 or L

This will give you the answer. {Molarity is number of moles in one litre (so moles/volume)}
0
4 weeks ago
#6
(Original post by flowerscat)
1 mole of glucose weighs 180 g
How many moles weigh 72 g?

Once you find the moles, use Concentration = moles / volume
Volume must be in dm3 or L

This will give you the answer. {Molarity is number of moles in one litre (so moles/volume)}
Ok, thanks. Does 0.20M sound right to u?
0
4 weeks ago
#7
(Original post by Amanda *M*)
Ok, thanks. Does 0.20M sound right to u?
Yes, it does 0
3 weeks ago
#8
(Original post by flowerscat)
Yes, it does Sorry to bother you again. I worked it out by dividing 72 by 180. But don't really understand why I did that? It seems strange to divide 72 by 180?
0
3 weeks ago
#9
You are not dividing 72 by 180. You divide 1 by 180, then multiply the answer by 72.

10 apples cost £50
How many apples can you buy for £8?

You would divide 10 by 50, to find the cost per apple, and then multiply the result by 8.

Same principle applies to your problem. Does this help?
0
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