Le Chatelier's Principle

Question 1

What is Le Chatelier’s Principle?

Answer 1

(1) For a system at dynamic equilibrium, (2) if a change is made to the condition, (3) the position of the erquilibrium will shift (4) to counteract the change

Question 2

When should you use Le Chatelier’s Principle?

Answer 2

when predicting how a dynamic equilibrium will respond to change

Question 3

What is the temperature rule of Le Chatelier’s Principle?

Answer 3

an equilibrium reaction will respond to counteract a change in temperature by shifting to RELEASE ↑ or CONSUME ↓ heat by favouring either the EXOTHERMIC ↑ or ENDOTHERMIC ↓

Question 4

What do endothermic reactions do?

Answer 4

they consume energy from their surroundings,

Question 5

What do exothermic reactions do?

Answer 5

they emit or expel heat into their surrondings

Question 6

Using L.C.P, how will a system respond when the temperature goes up?

Answer 6

the system will try to get rid of heat to lower the temp→ does this by favouring the endothermic reaction → which makes the system cooler by consuming heat

Question 7

Using L.C.P, how will a system respond when the temperature goes down?

Answer 7

the system will try to get more heat to increase the temp→ does this by favouring the exothermic reaction → which makes the system hotter by emitting heat

Question 8

Which reaction is favoured to increase the temperature?

Answer 8

the exothermic reaction

Question 9

Which reaction is favoured to decrease the temperature OR consume heat?

Answer 9

the endothermic reaction

Question 10

What is nitrogen dioxide?

Answer 10

NO₂ (g)

Question 11

What is dinitrogen tetroxide?

Answer 11

N₂O⁴ (g)

Question 12

What is the product and reactant in your nitrogen dioxide and dinitrogen tetroxide

Answer 12

reactant: nitrogen dioxide or 2NO₂
product: dinitrogen tetroxide or N₂O⁴

Question 13

What is the state of the substances in the 2NO₂ ⇆ N₂O₄ reaction?

Answer 13

gas

Question 14

What does “the equilibrium shifts to the left” mean?

Answer 14

the equilibrium shifts to the left = the reactants are now predominantly on the left

Question 15

What does “the equilibrium shifts to the right” mean?

Answer 15

the equilibrium shifts to the right = the reactants are now predominantly on the right

Question 16

What are the reactants and products when heating cobalt chloride hexahydrate?

Answer 16

reactants: CoCL₂ · 6H₂O (s)
products: CoCl₂ (s) + 6H₂O (g)

Question 17

What happens to the states in the “heating cobalt chloride hexahydrate” reaction?

Answer 17

goes from solid CRYSTAL reactants to solid and gaseous products

Question 18

What is the net ionic equation of heating cobalt chloride hexahydrate?

Answer 18

CoCL₂ · 6H₂O(s) ⇆ CoCl₂ (s)+ 6H₂O (g)

Question 19

What physically and visually happens when you heat cobalt (II) chloride?

Answer 19

the FORWARD or ENDOTHERMIC reaction is favoured → increases the concentration of the hydrated form of cobalt ion → solution turns blue

Question 20

What physically and visually happens when you cool cobalt (II) chloride?

Answer 20

the REVERSE or EXOTHERMIC reaction is favoured → increases the concentration of the dehydrated form of cobalt ion → solution turns pink.

Question 21

Is the forward or reverse reaction exothermic in the CoCL₂ · 6H₂O(s) ⇆ CoCl + 6H₂O (g) reaction?

Answer 21

reverse is exothermic

Question 22

Is the forward or reverse reaction endothermic in the CoCL₂ · 6H₂O(s) ⇆ CoCl + 6H₂O (g) reaction?

Answer 22

forward is endothermic

Question 23

What colour is the reactant CoCL₂ · 6H₂O(s) (hydrated cobalt chloride)?

Answer 23

pink

Question 24

What colour is the product CoCl₂ (s) (dehydrated cobalt chloride)

Answer 24

blue

Question 25

What is the name of CoCL₂ · 6H₂O(s)?

Answer 25

cobalt chloride hetrahydrate

Question 26

What happens to colours in the CoCL₂ · 6H₂O(s) reaction?

Answer 26

a visual change where the crystals go from pinkish/reddish to blue-ish

Question 27

What is the net ionic "iron thiocyanite and varying concentrations of ions" reaction?

Answer 27

Fe³⁺ (aq) + 3SCN⁻ (aq) ⇆ Fe(SCN)₃ (aq)

Question 28

Are the reactants or products favoured at standard conditions in the iron thiocyanate and varying concentrations of ions?

Answer 28

the reactants

Question 29

What is the colour of Fe(NO₃)₃ (aq) or net ionic-ly Fe³⁺?

Answer 29

yellow

Question 30

What is the colour of KSCN or net-ionic-ly 3SCN⁻ (aq)?

Answer 30

clear

Question 31

What is the colour of Fe(SCN)₃?

Answer 31

blood red

Question 32

What is the state of the reactants and products in the iron thiocyanite reaction?

Answer 32

Fe³⁺+ 3SCN⁻ ⇆ Fe(SCN)₃

Question 33

What happens if you increase the concentration of a substance using L.C.P?

Answer 33

the equilibrium will shift and the system will start to favour the reaction that uses up the extra/increased substance as a reactant.

Question 34

What happens if you decrease the concentration of a substance using L.C.P?

Answer 34

the equilibrium will shift and the system will start to favour the reaction that makes the decreased substance as a product.

Question 35

In what state can you not find the concentration of a substance?

Answer 35

Liquid and solid

Question 36

If everything in a system is equal, what does changing the amount of a solid substance do to the equilibrium?

Answer 36

nothing. Changing the amount of a solid does not affect the equilibrium

Question 37

If everything in a system is equal, what does changing the amount of a liquid substance do to the equilibrium?

Answer 37

nothing. Changing the amount of a liquid does not affect the equilibrium

Question 38

What is the unit of concentration?

Answer 38

moles per litre

Question 39

How does L.C.P apply to concentration?

Answer 39

if you change the concentration of a reactant or product by ADDING or REMOVING some, the equilibrium will shift to favour the reaction that USES UP or PRODUCES the same reactant or product to return the concentration to normal

Question 40

What colour is nitrogen dioxide?

Answer 40

brown

Question 41

What colour is dinitrogen tetroxide?

Answer 41

clear

Question 42

What are the two ways that pressure can be increased in a system?

Answer 42

1) pumping more gas (of the same concentration) into the system 2) reducing the volume of the system

Question 43

How can you decrease pressure in a system?

Answer 43

by increasing the volume

Question 44

The space that gas takes up depends on the number of what?

Answer 44

MOLES. less moles = less volume = less pressure more moles = more volume = more pressure

Question 45

What units is pressure measured in?

Answer 45

kilopascals

Question 46

What do coefficients have to do with moles?

Answer 46

The coefficients tell you how many moles of the substance are in the reaction. THere are 2 moles of 2NO₂ (g) present and 1 mole of N₂O₄.

Question 47

What is the net ionic equation of nitrogen dioxide to dinitrogen tetroxide?

Answer 47

2NO₂ (g) ⇆ N₂O₄

Question 48

What happens when you apply L.C.P to pressure?

Answer 48

an INCREASE or DECREASE in pressure will shift the equilibrium and force the system to favour the reaction that USES UP/CONVERTS the substances with the most moles or PRODUCES the substances with the most moles. E.g, 2 moles of gas will become 1 mol

Question 49

What happens if you increase the pressure using L.C.P?

Answer 49

the equilibrium will shift and the system will start to favour the side that uses the higher mole gas as a reactant, converting more moles into less moles

Question 50

What happens if you decrease the pressure using L.C.P?

Answer 50

the equilibrium will shift and the system will start to favour the side that uses the lower mole gas as a reactant, converting less moles into more moles

Question 51

Pressure and volume only affect what type of reactants or products?

Answer 51

gaseous