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A few basic Chemistry Qs (Mod 1+2)..HELP!

If anyone could please please help me, I'd really appreciate it! Got my exam on thursday :frown:

True or false?
1. Increase in pressure of a gas, increases concentration?
2. Le Chatelier principle affects yield produced, nothing to do rate?

3. What is the colour of aqeous chlorine? (green?) Aqeous fluorine?

4. Does AgF form? (When AgNO3 is added) or does it just stay as NaF for example? Would that be why it is colourless or no change in colour occurs when AgNO3 is added? If AgF does exist, is it soluble in NH3?

5. Why, in group 7, when more electrons down the group, why does this increase the boiling point?

6. Which molecules are diatomic?

Thank you!!

Reply 1

Whywhywhy

Sugaray

If anyone could please please help me, I'd really appreciate it! Got my exam on thursday :frown:

1. False
2. False
3. Green, and the other one I don't think you need to know
4. Prediction: soluble
5. Greater VDW's forces = stronger bonds between molecules
6. A lot

Reply 2

Sugaray

Whywhywhy

1. False - why?
2. False - why?
5. Greater VDW's forces = stronger bonds between molecules - why does more electrons = more VDWs?
6. A lot - is there any way to tell how?

Thanks

Reply 3

Barny

Sugaray

More electrons are being added, and these have to be accomodated in more principle energy levels, which are further from the nucleus, meaning that the atom is bigger - bigger VDW forces

Reply 4

Sugaray

imasillynarb

More electrons are being added, and these have to be accomodated in more principle energy levels, which are further from the nucleus, meaning that the atom is bigger - bigger VDW forces

Ok thanks

Any idea why these are wrong?
1. Increase in pressure of a gas, increases concentration?
2. Le Chatelier principle affects yield produced, nothing to do rate? - when equilibrium shifts it doesn't have any say on rate of the reaction does it? Thanks :biggrin:

Reply 5

z!D4N

imasillynarb

More electrons are being added, and these have to be accomodated in more principle energy levels, which are further from the nucleus, meaning that the atom is bigger - bigger VDW forces

not necessarily... it's the increase in number of electrons which increases the chance of temporary dipoles per unit time, hence VDW forces increases.

Reply 6

daydream

Sugaray

Ok thanks

actually i think 1. is right. pressure is caused by collisions on the surfaces and between molecules.. so increasin pressure means unit per volume is greater so concentration is lerger

Reply 7

Dan_Crew

1. Yes

2. On reaching equiblirum if the system is altered the postion of equilbrium will move to appose the change.

3. Green, Yellow

4. A cream precipitate would be formed.

5. Beacuse the atomic radi of the elemnts is increasing due to a greater nucleaur charge.

6. The halogens (group7)

6. Oxygen, Fluorine, Clorne, Iodine

Thank you!!

Reply 8

supreme

Sugaray

If anyone could please please help me, I'd really appreciate it! Got my exam on thursday :frown:

True or false?
1. Increase in pressure of a gas, increases concentration?

2. Le Chatelier principle affects yield produced, nothing to do rate?

3. What is the colour of aqeous chlorine? (green?) Aqeous fluorine?

4. Does AgF form? (When AgNO3 is added) or does it just stay as NaF for example? Would that be why it is colourless or no change in colour occurs when AgNO3 is added? If AgF does exist, is it soluble in NH3?

5. Why, in group 7, when more electrons down the group, why does this increase the boiling point?

6. Which molecules are diatomic?

Thank you!!

1. The effect of increasing the pressure of a gas is the same as increasing the concentration of a solution

2. If a factor which affects the position of equilibrium is altered, the equilibrium changes and shifts in the direction which tends to reduce (and oppose) the change.

Remember that catalyts work on both the forward and reverse reactions, they have no effect on the position of equilibrium but they can increase or reduce the rate at which equilibrium is reached.

3. yellow (i am not 100% sure on this)

4. See attachment

5. more VDW forces => higher bp

6. the halogens

distinguishing between halide ions.jpg102.0KB

Reply 9

Sugaray

supreme

Thanks for that scan! :biggrin:

And thanks everyone for all the help!

Reply 10

Barny

supreme

Seems youve got the same revision guide as me :smile:

Reply 11

FidoDiDo

Sugaray

If anyone could please please help me, I'd really appreciate it! Got my exam on thursday :frown:

1.True Concentration is used for liquids .. Pressure used for gases
2.True if a change occur in a system of equilibrium .. Microscopic process takes place to oppose this change[ didnt mention rate ]
3.aqeous flourine i assume pale yellow
5.Well becuz there is an increase in polarisability .. i.e its easier for the electron cloud to be distorted to form a dipole .. so the Vand der waal forces are stronger
6.Non-metallic elements of group 7 - 6 - 5

Reply 12

A0307

I see your questions have already been answered, but I always found this useful:

Reply 13

FidoDiDo

calumc

I see your questions have already been answered, but I always found this useful:

LoooL .. Could it be More usefull :biggrin:

Reply 14

supreme

imasillynarb

Seems youve got the same revision guide as me :smile:

Lol but it is scary as I can see the pages in my mind. :eek:

Reply 15

supreme

Sugaray

Thanks for that scan! :biggrin:

And thanks everyone for all the help!

Reply 16

zombie

supreme

Lol but it is scary as I can see the pages in my mind. :eek:

Lol, I do that in the exam - I start picturing the page of stuff I have to remember and I can actually see the sentences right there... wierd, but I spose it happens after staring at a page for hours on end!

Reply 17

A0307

FidoDiDo

LoooL .. Could it be More usefull :biggrin:

That particular version is slightly less useful than it at first appears.

I have no idea where I got it from, probably revising for chemistry or something.