Questions -- pretty much on every frikkin thing >_>"

[lauzy358]

Well, it's about time I started my own questions thread xp I have heaps, haha.


A mixture of NO and NO₂ was prepared by reacting copper with nitric acid. The mixture of gases was passed through water, which removed the NO₂, leaving the NO. This gas was then passed through concentrated sulfuric acid. In this last step sulfuric acid was acting as:
answer was dehydrating agent

Could someone please show me the reaction for the last step? So, NO + H₂SO₄ --> ?

Thanks!<3

[bec]

Is it just, NO(aq) ----H₂SO₄--> NO(g) ? (someone confirm?)

[Pandemonium]

that is correct bec.

[lauzy358]

..oh. *facepalm* thanks, it's obvious now you're pointed it out x.x

A student calibrated a solution calorimeter containing 100mL of water using electrical apparatus. The specific heat capacity of water is 4.18 J/C/g. Assuming that the student's measurements were reliable, which calibration factor is most likely for a well-insulated calorimeter?
A 240 J/K
B 480 J/K
C 960 J/K
D 1418 J/K

._.

[Mao]

calibration factor is the energy required to raise the contents by 1 degree Celsius (equivalent to 1K)

hence, to raise 100mL of water by 1 degree Celsius, you will need

[lauzy358]

edit. sry just went over that calibration thing again, the answer's meant to be 480 J/K. I get what you're saying Mao, but is the answer 480 because you have to account for the heat energy used to heat up the components of the calorimeter too?
---

omfg the simplicity of my questions is starting to embarrass me.
oh well, here's another:

it's electrolysis.
half reaction at negative electrode/cathode:
Cu²⁺_(aq) + 2e^- --> Cu_(s)

half reaction at positive electrode/anode:
2H₂O_(l) --> 4e^- + 4H⁺_(aq) + O_2(g)

After electrolysis has been continued for a long time, it is observed that a gas is being evolved from the negative elctrode. Write the half reaction for the process responsible for the evolution of the gas.
answer's 2H₂O_(l) + 2e^- --> H_2(g) + 2OH^-_(aq)

Why can't it be 2H⁺_{(aq) + 2e^-} --> H_2(g)? it's got a higher E⁰... and H⁺ was being produced at the positive electrode anyway.

Kinda of sleepy so excuse typos and things.
thanks<3

[Glockmeister]

Probably cause it's not being produced at the negative electrode I would think.

[onlyfknhuman]

How do u convert from  J/C to J/K?

[Collin Li]

Per Celcius and Per Kelvin are the same thing. Celcius is just a translation away from Kelvin, the scale is the same.

[lauzy358]

Probably cause it's not being produced at the negative electrode I would think.

since it's all in one cell, can't the H+ migrate to the negative electrode & be consumed though?

[lauzy358]

The two questions below apply to this diagram-
[img=http://img339.imageshack.us/img339/2636/chem1wr9.th.jpg][img=http://img339.imageshack.us/images/thpix.gif]

The question was a "pick the right statement" thing and the following statement was incorrect, why?
Current passes from tin electrode to silver electrode through the external circuit.

---

The potential difference of the cell can be increased by,
answer - Increasing the Ag+ ion concentration

How does that work? I don't get how you could increase the potential difference...unless you changed the metal being used...

edit. another question just occurred to me~

electrolytic reaction of I- and Cu2+...
H2O can't react in preference to Cu2+ because O2 is required, right? or is O2 and H2 just taken for granted to be always present, since they're just in the atmosphere and the cells aren't airtight... ... ._x

[lauzy358]

Does the pressure of the reaction mixture decrease by 50% as the reaction proceeds in the forward direction?
I said yes but the answers didn't have the same opinion =T

[onlyfknhuman]

how does the pressure decrease as a reaction proceeds logically doesnt make sense at all O_O i thought that pressure always remained constant, unless stated otherwise from something external. And that the only thing that changes during a reaction is the reaction rate due to the consumption of reactants, and wether if its exothermic or endothermic. If its exothermic it will increase the rate as it gives off heat. And endo it wont as it absorbs heat.

[shinny]

Does the pressure of the reaction mixture decrease by 50% as the reaction proceeds in the forward direction?
I said yes but the answers didn't have the same opinion =T

Not sure if this is the reason, but I think it's because only the PARTIAL PRESSURES of each reactant change, not the net pressure of the reaction system.

[azn_kiwi91]

Does the pressure of the reaction mixture decrease by 50% as the reaction proceeds in the forward direction?
I said yes but the answers didn't have the same opinion =T

Not sure if this is the reason, but I think it's because only the PARTIAL PRESSURES of each reactant change, not the net pressure of the reaction system.

Isnt the reason because the sulfur is in liquid state? ie. only the oxygen and SO2 affect the pressure, so as one is consumed, the other is produced?