0
votes
0answers
6 views
what is the basicity constant and how is it calculated?
what is the basicity constant and how is it calculated?
1
vote
0answers
9 views
Questions regarding the 2008 CHEM exam 2
In the short answer section, question 6: "the value in JKmol-1 of deltaH for the reaction written is asked for. Where is this knowledge supposed to come from? Is this part of a num …
0
votes
0answers
7 views
why electrolytes they migrate to the anode to carry charges?
why electrolytes they migrate to the anode to carry charges?
2
votes
1answer
23 views
Write half equations for (S2O3) ^(2-) + (2H+) -> S + SO2 + H2O
I think it's
S2O32- + 6H+ + 4e- -> 2S + 3H20
S2O32- + H20 -> 2SO2 + 2H+ + 4e-
Which one's the oxidation and which is reduction?
Do we need states in half equations?
Also, sho …
1
vote
0answers
5 views
Why aren’t all batteries rechargable?
In a secondary cell the products of the discharge reaction stay in contact with the electrode. Hence, by adding electricity to them you can recharge them. In normal store batteries …
2
votes
1answer
18 views
A 0.20M solution of a weak acid has a measured pH of 4.0. The Ka of this weak acid is…
NOT 5x10^-4 as I had thought.
Why is this?
The actual answer is 5x10^-8
-1
votes
0answers
16 views
How does I interpret the method in this equilbrium experiment?
I do not understand the rationale behind each dot point under step two of this excerpt from an experimental method. Would someone be able to explain about how this relates to conta …
3
votes
0answers
20 views
reaction ^-2? something missing?
s203 ^2- + 2H+ <---> S + SO2 + H2O
That is an equation given in my prac booklet at school.
We are asked to write the half equations for the reaction.
Isn't that above reac …
2
votes
0answers
15 views
The ‘BLACKOUT’ prac
Has anyone done the "blackout" prac before, or know of it? I'm doing it at school and I don't understand the rationale of it.
Doesn't the whole equilibirum thing screw up the ch …
1
vote
1answer
11 views
How much water needs to be added to change the pH of 2L of vinegar from 2 to 3?
If we have 2L of pH 2 vinegar, and we want to make it pH 3, how much water do we add and why?
2
votes
1answer
39 views
Electrolysis Electrochemical Series Question?
Lithium metal is prepared by electrolysis of a molten mixture of Lithium Chloride and Potassium Chloride, write the half equations for the reactions occurring at the cathode and an …
3
votes
2answers
22 views
What do electrolytes do in batteries/cells?
What do electrolytes do in batteries/cells?
2
votes
1answer
30 views
What is numerical value for the heat of combustion of propanol?
This question was inspired from a past exam paper. See exam-spoiler for more questions of this type.
In the 2008 unit 4 Chemistry exam, there was a question which asked:
W …
1
vote
1answer
23 views
How do you determine the Ka value from a given pH?
This question was inspired from a past exam paper. See exam-spoiler for more questions of this type.
Can you determine the acidity constant with only the pH of different acids …
2
votes
1answer
8 views
‘recovering’ primary cells = recharging?
Zinc-Carbon dry cells are considered primary cells, thus non-rechargable. Meanwhile, they can 'recover' from polarisation and continued to be used indefinately, unless they are let …
