Chemistry: Post your doubts here!

[krishnapatelzz]

Cn any1 pls tell me if group 4 is removed frm da syllabus? (Ge/Sn/Pb etc)

yea it is removed/ it is not there in 2017 http://www.cie.org.uk/images/164502-2016-2018-syllabus.pdf check out the new syllabus .

 

[3abder7man]

Salam everyone

Can anyone please explain why the answer is A?

 

[DragonCub]

Salam everyone

Can anyone please explain why the answer is A?

Use Le Chatelier's Principle for this question.

Le Chatelier's Principle dictates the equilibrium position to shift to one side (product or reactant), in order to counter any effect from changes in state (temperature, pressure, etc.).
In this case, the "state" that has changes is the pressure, which decreases.
Therefore, the equilibrium position needs to go in a direction that tends to raise the pressure back up. So which direction will it go?

Looking at the equation, we can see that 2 mol of reactant turns into 1 mol of product - there is a general decrease in molar amount along the reaction.
This means the forward reaction acts to lower the system's pressure, thus the backward raises it up.

Therefore, the equilibrium position shall shift towards the reactant side, and will make the mixture even more dark brown.
However, the initial state is already dark brown, so there is no visible change.

 

[Bhaijan]

Please explain Question 5(b), Is this a Ligand exchange reaction?

 

[Thought blocker]

Please explain Question 5(b), Is this a Ligand exchange reaction?
View attachment 61747

This topic is removed from the syllabus.

 

[krishnapatelzz]

Please explain Question 5(b), Is this a Ligand exchange reaction?
View attachment 61747

this topic is removed , please check the syllabus before solving any paper before 2016 http://www.cie.org.uk/images/164502-2016-2018-syllabus.pdf

 

[Thought blocker]

this topic is removed , please check the syllabus before solving any paper before 2016 http://www.cie.org.uk/images/164502-2016-2018-syllabus.pdf

You can give it a try if you wanna. xD

 

[krishnapatelzz]

You can give it a try if you wanna. xD

hahahah no

 

[student2]

whats the vol. capacity of syringe?
n does any1 know whn to use a syringe n whn a downward displacement?

 

[Thought blocker]

whats the vol. the capacity of a syringe?
n does any1 know when to use a syringe n when a downward displacement?

In context to paper 5, you can take any sensible volume of the syringe during experiment according to the given situation.
We use gas syringe to measure the amount of gas produced in some experiment.
Check this : https://socratic.org/questions/why-can-hydrogen-be-collected-by-the-downward-displacement-of-water

 

[student2]

Cn any1 pls help me with ths? I dont understand ths
(s11_qp_41)( Q8, c)

 

[Thought blocker]

View attachment 61756

Cn any1 pls help me with ths? I dont understand ths
(s11_qp_41)( Q8, c)

M + 2 peaks are of similar height. 1:1 ration, thus X should be bromine.
If you wanna know more about this, click here.

 

[yamna121]

[QUOT

Two equilibria are shown below.

reaction I 2X2(g) + Y2(g) gives 2X2Y(g)
reaction II X2Y(g) gives X2(g) + 1/2Y2(g)

The numerical value of Kc for reaction I is 2.

Under the same conditions, what is the numerical value of Kc for reaction II?

Why is the answer 1/root2???

 

[Thought blocker]

[QUOT

Why is the answer 1/root2???

?

 

[yamna121]

?

the answer to this question is 1/squareroot of 2 . how did we get that??

 

[Thought blocker]

the answer to this question is 1/squareroot of 2 . how did we get that??

 

[yamna121]

View attachment 61766

okhh!!!!, thanks alott and means alot!!!!

 

[Keshani Privinsha]

Phosphorus forms a compound with hydrogen called phosphine, PH
3
. This compound can react
with a hydrogen ion, H
+
.
Which type of interaction occurs between PH
3
and H
+
? (9701/12/m/j/15)

 

[Keshani Privinsha]

Metaldehyde, (CH
3
CHO)
4
, is used as a solid fuel for camping stoves. The equation for the
complete combustion of metaldehyde is shown.
(CH
3
CHO)
4
(s) + 10
O
2
(g)
→
8CO
2
(g) + 8H
2
O(l)
= standard enthalpy change of combustion.
Which expression will give a correct value for the enthalpy change of formation of metaldehyde?

 

[Keshani Privinsha]

When 3.00
g of an anhydrous nitrate of a Group II metal is decomposed, 1.53
g of gas is
produced.