AS Chemistry- helping each other out!

can someone explain this to me please? (aqa board)
In terms of atomic structure, explain why the van der Waals’ forces in liquid argon arevery weak.

Hi could someone explain how to find the answer to this question/questions like this? Is it something to do with equilibria favouring fwd reaction due to the fact you added OH ions (and it wanted to revert back by adding more H ions? And because the fwd reaction causes yellow colour, the solution just remains yellow? Or something else




Thanks

The OH ions from the sodium hydroxide will react with the H+ on the right hand side to form H20 and therefore the H+ ions from the equilibrium is removed. Can you now see which direction the equilibrium will shift to compensate?

Could you guys help me out on structure & bonding?

I just don't understand how to work out the final shape of the molecule l, like do you guys have any tips? xx

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As you go across a period, the amount of protons increases. This increases the attraction between the outer shell electrons and the nucleus, which draws in the outer shell electrons more, making the atom smaller. The smaller the atom, the weaker the Van Der Waals forces of attraction.

Could you guys help me out on structure & bonding?

I just don't understand how to work out the final shape of the molecule l, like do you guys have any tips? xx

Posted from TSR Mobile

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This helps . This is how I do it..
So for example.. BCl3
I would find the amount of e- in central atoms outer shell in this case B (group 3 so 3)
B = 3e-
3Cl e- = (3+3 = 6e- /2 so 3 electron pairs and 3 bonding pairs, no lone pairs
if you learn the table you'll know it's trigonal planar

I'm kinda replying a bit late but you guys gave me really good advice. I'm actually doing the full alevels here biology, chemistry and maths this yr plus as physics. I've been off tsr and managed to get AS + half A2 maths, AS biology and a little bit of chemistry and physics done this week (learnt and understood, did some practice questions on topics as I learnt them, I also plan to do the papers real soon). The splitting into chapters and topics technique makes it easier to learn the stuff and seems less overwhelming. Thanks so much.

btw what's georgiam247, what's LTM?

need help in gce paper unit 1 chemistry question 16 b (ii) which is Suggest how you would mix the acid and the coral to ensure that no carbn dioxide escaped from apparatus... ive found an old TSR thread with various answers.. does this look good. what is the "perfect answer"??

From old TSR thread:

Stick coral to a bung half fill test tube with acid put bung into test tube shake or flip the other way up so they come into contact In the sealed test tube

Hi. I'm getting slightly confused over calculating the different types of enthalpy changes. I used to be OK with this, but for some reason, the way I've always used isn't getting me the right answer in this particular question.

So, my understanding:

∆H_r = ∑∆H_c (reactants) - ∑∆H_c (products)


So in a question like this:

Given the following data:

Substance	H2O(l)	CO2(g)	Ethane C2H6(g)	Ethene C2H4(g)
∆Hf/kJmol-1	-285.5	-393	-83.6	+52.0

Calculate the enthalpy of combustion of Ethane.

Would you use the equation I gave above? Or would you simply use the products - reactants formula.

Also, please can you explain why you used the particular method you did, as I believe this is where my knowledge is lacking.

On a question like this you it's always best to draw a Hess cycle for the information you've been given and the info you want to find out

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