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Reply 1

Um I don't know if this is what you're looking for, but here you go:

Sulphamic acid reacts with sodium hydroxide according to the following equation:
NH2S03H + NaOH ---> NH2SO3Na + H20
A standard solution of sulphamic acid was made by dissolving 5.210g of the acid in water and making the volume up to exactly 250cm3 with more water

a) Calculate the number of moles of acid used and the molarity of the acid solution.

b) In a titration, 22.6cm3 of this acid solution were required to neutralise 25.0cm3 of sodium hydroxide solution. Calculate the molarity of the sodium hydroxide solution.

Reply 2

Widowmaker
E.g. on titration calculations and identifying salts?
E.g. you give me a situation such as, heat a compound X, a lilac flame is produced therefore it is a potassium compound, but I have to give the answer.

What level / Exam board?

Reply 3

BarelyLegal
Um I don't know if this is what you're looking for, but here you go:

Sulphamic acid reacts with sodium hydroxide according to the following equation:
NH2S03H + NaOH ---> NH2SO3Na + H20
A standard solution of sulphamic acid was made by dissolving 5.210g of the acid in water and making the volume up to exactly 250cm3 with more water

a) Calculate the number of moles of acid used and the molarity of the acid solution.

b) In a titration, 22.6cm3 of this acid solution were required to neutralise 25.0cm3 of sodium hydroxide solution. Calculate the molarity of the sodium hydroxide solution.


a) NH2S03H
5.210 grams
Molar mass = 97

No of moles = 5.210/97 = 0.0537 moles
=> 5.210/97 = (250*C)/1000
=> 5.210/97 = 0.25C
C = (4*5.210)/97 = 0.215 moldm^-3

b)
NH2S03H
V = 22.6cm3 = 0.0226dm^3
C = 0.215 moldm^-3

NaOH
V = 25.0cm3 = 0.025dm3
C = ?

At the equivalence point, the number of moles are equal.

no of moles of sulphamic acid = 0.0226*0.215 = 4.859*10^-3
=> no of moles of NaOH = 4.859*10^-3

4.859*10^-3 = 0.025C
C = 0.194moldm^-3

Reply 4

TakemetoAvalon
What level / Exam board?

edexcel AS

Reply 5

Widowmaker
a) NH2S03H
5.210 grams
Molar mass = 97

No of moles = 5.210/97 = 0.0537 moles
=> 5.210/97 = (250*C)/1000
=> 5.210/97 = 0.25C
C = (4*5.210)/97 = 0.215 moldm^-3

b)
NH2S03H
V = 22.6cm3 = 0.0226dm^3
C = 0.215 moldm^-3

NaOH
V = 25.0cm3 = 0.025dm3
C = ?

At the equivalence point, the number of moles are equal.

no of moles of sulphamic acid = 0.0226*0.215 = 4.859*10^-3
=> no of moles of NaOH = 4.859*10^-3

4.859*10^-3 = 0.025C
C = 0.194moldm^-3

Can someone check if this is correct? Question is above.

Reply 6

Widowmaker
Can someone check if this is correct? Question is above.

Yes it is correct as far as I can see.

Reply 7

oxymoron
Yes it is correct as far as I can see.

that's good, thankyou.
Do you know anything about the edexcel AS Chemistry practical?

Reply 8

Widowmaker
that's good, thankyou.
Do you know anything about the edexcel AS Chemistry practical?

Did you do enthalpy change practice? Something like measure the temperature before and after the reaction ... then draw a graph, from it you can calculate the enthalpy change?

Reply 9

Describe the effect of a nitro-substituent on directing the site of reaction in the electrophilic substitution of an aromatic compound (e.g. benzene). Rationalise that effect by considering charge stabilisation.

Reply 10

BCHL85
Did you do enthalpy change practice? Something like measure the temperature before and after the reaction ... then draw a graph, from it you can calculate the enthalpy change?

yeah I can do those experiments no probs. my teacher put a notice up in the lab saying that one experiment is a titration, (probably sodium hydroxide and an acid and methyl orange as an indicator) and the other is identifying salts.
2 hours for each practical, but i'm just swotting up on these types of practicals, common mistakes and calculations.

If there are only two practicals, will there be a planning element to these practicals at all?

Reply 11

ChemistBoy
Describe the effect of a nitro-substituent on directing the site of reaction in the electrophilic substitution of an aromatic compound (e.g. benzene). Rationalise that effect by considering charge stabilisation.

Sure those aren't A2 problems? I never covered substitution is Higher...

Reply 12

ChemistBoy
Describe the effect of a nitro-substituent on directing the site of reaction in the electrophilic substitution of an aromatic compound (e.g. benzene). Rationalise that effect by considering charge stabilisation.

read what I am typing, I am not doing that!

Reply 13

Widowmaker
read what I am typing, I am not doing that!

widomaker, where did you get your avatar? I think i might steal it :biggrin: I made mine! I can't be bothered searching...

Reply 14

TakemetoAvalon
widomaker, where did you get your avatar? I think i might steal it :biggrin: I made mine! I can't be bothered searching...

lol, I saw it quite familiar, is it in "spirited away" ?

Reply 15

BCHL85
lol, I saw it quite familiar, is it in "spirited away" ?

Yeah, that's right.. the little dudes made out of soot!

Reply 16

Please don't steal my avatar.
Can anyone give me any other practice questions?
ask me questions about safety, titrations and precautions to be taken, and identifying salts (edexcel) mainly groups 1,2 and 7.

Reply 17

Widowmaker
Please don't steal my avatar.
Can anyone give me any other practice questions?
ask me questions about safety, titrations and precautions to be taken, and identifying salts (edexcel) mainly groups 1,2 and 7.

Sorry about that :biggrin:
I'm sure you'll be fine in your practical exam. If the question is indentifying a compound , you should remember how to realise all the substance, cations, anions, gas, solid ... either by colour or smell, litmus paper, flame test, ect. Did you have the summary note of these?

Reply 18

BCHL85
Sorry about that :biggrin:
I'm sure you'll be fine in your practical exam. If the question is indentifying a compound , you should remember how to realise all the substance, cations, anions, gas, solid ... either by colour or smell, litmus paper, flame test, ect. Did you have the summary note of these?

yeah, i've made my own revision notes. I printed off the spec last week.

Reply 19

I'm trying to see if there are any more titration precautions.
Here is my list.

Ensure that solution does not go above 0 in burette.
Check for bubbles in burette and above burette tap.
Ensure tap is closed when pouring solution into burette.
Funnel must be removed from burette after solution has been poured in.
Volumetric flask must be shaken 10-15 times to ensure solution is mixed.

I'm sure there are more obvious ones. Can you think of any?