Chaoter 19 equilibrium

Question 1

How to find kf if it’s homogenous vs heterogenous equilibrium

Why do we omit and for what? (Gas and?)

Answer 1

Homogenous = use concentrations as normal as all the same

Heterogenous = OMIT SOLID AND LIQUID BECAUSE RHEY ARE BASICSLLY CONSTANT

So heterogenous only takes into account of the gases AND AQUEOS SOLUTIONS

Question 2

What state of the concentrations must it be to work out KC?

Answer 2

Must be at EQUILIBIRUM

Question 3

How can you work out equkibkrum concentrations

Answer 3

With a mixture volume same, jus need moles and then divide shc

Write initial moles and end , find change and equate to the stocihemetirc

Question 4

How do you know where to add or subtract the moles when working out moles at EQUILIBIRUM

Answer 4

Left side = subtract, right side just add

Question 5

Even if they mention moles of water in an acid calatsyt, do you add to moles of water at the start?

Answer 5

Yes you do , any sign if that rwxgstn make sure to write it down

Question 6

How to be able to tell if a mixture truly in EQUILIBIRUM after leaving for a week

Answer 6

Jus do another mixture with same amounts as control, if after a week they show same concentrations then it probably is

Question 7

How to use titrations to work out the amount of say an acid in equilibrium after an experimental thing

Assuming there is an acid catalyst

Answer 7

You would use titrations to see how much acid is used in both

And then bare in mind the acid catalyst aswell, you can then subtract them to find

Question 8

How to work out mole fraction

Answer 8

Literally mole over total mole

Question 9

How to work out and what is partial pressure

Answer 9

Volume that contributed is promotional to moles, so partial pressure is linked with moles

Partial pressure is just the amount of total pressure individual pressure contributed

Thus it’s moles x total pressure!

Question 10

How to check your partial pressure and mole fraction correct

Answer 10

If they sum to 1 and total pressure both time

Question 11

What is k p
How to calculate

Answer 11

This is the EQUILIBIRUM constant too but using gases and partial pressures

Same as kf but using partial pressures instead

Question 12

As kp is to do with gas, what must be ignored
Compared to kc

Answer 12

Kc is aq and g

Kp only gas

Question 13

What effect changes the value of the EQUILIBIRUM constant K

Answer 13

ONLY TEMPERTAURE

It’s a constant so things like pressure and volume , concentration would still make this a constant

However the TEMPERTAURE is only thing to change the K

Question 14

What is the effect on kp or KC if you increase temp and it’s exothermi vs endothermic

Answer 14

Endothermic the Kp increases with temp

Exothermic the kp decreases with temp

(Remmeber this to do with the quantiles increasing or decreasing due to le chatelier ( of really) and so that’s how you can remember)
For example endothermic it will go forward, more product over reactant = increase

Question 15

How to explain the changes in TEMPERTAURE pressure and conc really for k, and effect on other conc or pressure

Answer 15

With TEMPERTAURE see the change in k value and then use proportions to justify

For pressure and conc, k value is THE SAME, so can justify the change in proportions as they have to equal the same k value again

Question 16

So for change in conc how can explain where equilibrium moves

Answer 16

Kc must be equal, so if product increase, now this is bigger than kc, so product must decrease and reactant increase, shift to left - which matches le Chatellier

If reactant increase, this is less then kc so reactant must decrease and predict increase, moves to right, which works out too

Question 17

What about an increase in pressure in general / decrease?

Answer 17

Increase in pressure increases the partial pressures of both reactant and product

But depending on the mole ratios it won’t be the same increase, giving a new kp which is bigger or smaller than before, unless same number of moles

As a result you say products and reactants would increase or decrease to match same kp as before

Question 18

Again summary in how to explain changes to equilibrium for K with TEMPERTAURE, and conc and pressure when temp constant

Answer 18

See new value and adjust accordingly, for k and T see new K , for conc and pressure it had ti match same kc as before

Question 19

Proper answer for changing pressure

Answer 19

KC is constant
Increasing pressure increases concentration terms more at the (top or bottom then the other)
- no longer balances so change must happen
-to return to kc
- overall effect is shift to left or right

Question 20

How to interchange between partial pressure and mole fraction

Answer 20

Mole fraction times total pressure is partial pressure
Partial pressure over oral pressure is mole fraction

And partial pressure lit jus the SEPARATE PRESSUES THEY ARE AT