that acid 1 acid 2 question (1 Viewer)

annabackwards

<3 Prophet 9
Joined
Jun 14, 2008
Messages
4,670
Location
Sydney
Gender
Female
HSC
2009
This^^^

Whether it's valid for the question or not is another thing =p
Aha i wrote both. Well i just wrote the equation on the side but the words "Potassium acetate" was on the lines so i should be alright.

Gah i can't remember which acid i said was more concentrated >.<"
 

ashllis92

Member
Joined
Sep 27, 2009
Messages
289
Gender
Female
HSC
2009
By the shape of the titration curve for acid 2 could you assume it was diprotic? It started steep and then tapered off, not smooth like acid 1 suggesting two protons donated.

This would make it a strong, concentrated diprotic acid such as sulfuric?
The question said that both acids were monoprotic...
 

Shoom

Member
Joined
Aug 26, 2008
Messages
695
Gender
Undisclosed
HSC
N/A
I said ACID 1 was stronger then acid 2, shown by the lower pH on the graph, then I defined how we know if an acid is strong or eak, then I said its possible to have a strong and dilute acid and a weak but concentrated acid.
 

ashllis92

Member
Joined
Sep 27, 2009
Messages
289
Gender
Female
HSC
2009
I didn't think that HF even fully dissociated so how can it be strong?
 

paige92

New Member
Joined
Feb 24, 2008
Messages
2
Gender
Female
HSC
2009
oh btw guys, the question said explain the difference in strength and concentration, i.e. identify that acid 1 was stonger than 2 but less concentrated than 2 and hence explain what that meant in terms of acid 1 having more molecules ionised in soln (strength), but acid 2 having more acid molecules per volume of water (concentration)...well thats what my chemistry teacher said and hes a senior hsc marker...
 

Abdo_1

New Member
Joined
Mar 15, 2009
Messages
4
Gender
Male
HSC
2009
Yeah I put the salt as CH3COOK, The first acid was stronger as it had a steeper titration curve, the second was weaker as it had a shallower titration curve. The first was more dilute because it took less to neutralise than the second because it was further left.
its not about the steepness of the titration curve, its by finding the equivalence point.
a strong acid and strong base always have an equivalence point at a pH of 7.
thats how you could tell its a strong acid. i think that was acid one, the one with the 'steep' curve.
 

Abdo_1

New Member
Joined
Mar 15, 2009
Messages
4
Gender
Male
HSC
2009
oh btw guys, the question said explain the difference in strength and concentration, i.e. identify that acid 1 was stonger than 2 but less concentrated than 2 and hence explain what that meant in terms of acid 1 having more molecules ionised in soln (strength), but acid 2 having more acid molecules per volume of water (concentration)...well thats what my chemistry teacher said and hes a senior hsc marker...
yes thats the answer pretty much.
and you could find the concentration of hydrogen ions because at 20mL the pH was 2 (by memory) and [H+]=10^-pH
 

mR sinister

Member
Joined
Nov 24, 2008
Messages
127
Gender
Male
HSC
2009
This is how i done that question.
First you look at the intial pH of both acids, i.e BEFORE the titration.

1 had a ph of 2, and the other of about ~1.2 or smthing.

then you use the formula [H+] = 10^-pH
To find the [H+] concentration. Obviously the acid which had ~1.2 pH was more concentrated.
however that acid was weaker than the one with the pH value of 2. you could tell this by just looking at the graph and comparing the times its took to reach equivalence point.

And hence that's why i wrote KCL as my salt.
 

chuboy

Member
Joined
May 14, 2009
Messages
121
Location
Northern NSW
Gender
Male
HSC
2009
This is how i done that question.
First you look at the intial pH of both acids, i.e BEFORE the titration.

1 had a ph of 2, and the other of about ~1.2 or smthing.

then you use the formula [H+] = 10^-pH
To find the [H+] concentration. Obviously the acid which had ~1.2 pH was more concentrated.
however that acid was weaker than the one with the pH value of 2. you could tell this by just looking at the graph and comparing the times its took to reach equivalence point.

And hence that's why i wrote KCL as my salt.
Acid 1 was a less dilute, strong acid. Acid 2 was a more concentrated, weak acid. The volume of KOH showed which was more dilute/concentrated, the pH showed whether an acid was strong or weak. As KOH is a strong base, only a strong acid would have neutralised at pH 7.

Unfortunately, your salt is wrong too. KCl would form from potassium hydroxide and hydrochloric acid. You were asked to name a salt from an acid similar to acid 2. Acid 2 was a weak acid.
 

mR sinister

Member
Joined
Nov 24, 2008
Messages
127
Gender
Male
HSC
2009
Acid 1 was a less dilute, strong acid. Acid 2 was a more concentrated, weak acid. The volume of KOH showed which was more dilute/concentrated, the pH showed whether an acid was strong or weak. As KOH is a strong base, only a strong acid would have neutralised at pH 7.

Unfortunately, your salt is wrong too. KCl would form from potassium hydroxide and hydrochloric acid. You were asked to name a salt from an acid similar to acid 2. Acid 2 was a weak acid.
thats, what i ment woops, wrote it the other way round

but yes i used the wrong salt :burn: STUPID ME
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top