Alot of chem questions! (1 Viewer)

[kiniki]

Hi guys, didn't know what subforum to put this thread in since these are mainly prelim questions.

I'm looking over some experiments I failed to hand in yr 11 and i just realised I can't answer half the questions...


1) If 100ml of 1.0M H2S04 reacted w/ 100ml of 1.0M NaOH or 1.0M KOH solutions, how would the amount of heat compare with that obtained for the reaction of the alkali solutions with 100ml of 1.0M solutions of HCl and HNO3 solutions as measured in this experiment? Explain your reasoning.

2) The enthalpy of neutralisation of antimonic acid H7Sb06 is -55 kJ mol ^ -1
What can you conclude about the chemical behaviour of antimonic acid from its enthalpy of neutralisation?
2i) Write a balanced thermochemical equation for the complete neutralisation of this acid with NaOH

3) With the aid of reaction profile and reactant energy distribution diagrams explain how catalysts are able to accelerate the rates of reactions according to the collision theory

4) Compare the enthalpy of fusion for water determined in the prievous experiment with the enthalpy of vaportisation of water calculated in this exp. Account for the differences in the magnitudes of these 2 enthalpies.



I've got some results and calculations and stuff if anyone wants them, but these questions are asking for my knowledge...

I look at these and go absolutely 'WTF AM I READING' I have no idea how to calculate enthalpies nor do i understand any of the aforementioned questions..
I'm not asking you to do my homework since I really really want to go well in chemistry this year..

Help

 

[flaminwaffle]

you definitely didnt have enough knowledge to answer q1 in year 11. hec, it might take till the end of this topic before you actually understand it. your teacher shouldnt have given it to you.

however, i did study enthalpy in year 11. it is basically the energy stored within a reaction.

ill give you an example.
i know that the reaction HCl (l) -> H+(aq) + Cl-(aq) is exothermic. (This is the reaction when HCl acid is dissolved in water)
let's say for example sake that the left side of the reaction has 100joules of energy. that is, the energy within and between the atoms of HCl is 100joules. this is its 'enthalpy'. let's say the right side of the reaction has an enthalpy of 80 joules. Thus, when you dissolve HCl in water, the left side has an excess of 20 joules of energy. This energy must go somewhere, and is released to the environment as the form of heat. This is the actual reasoning behind why the reaction is exothermic, because it RELEASES those extra 20 joules of energy.

The opposite is true for endothermic reactions, where the left side has a lower enthalpy than the right side of the reaction.

your teacher may be able to explain better than me. but i look at question 2 onwards and i go 'wtf', and i got a b6 in chemistry. those are not hsc style questions, so dont stress too much over them.