topic 11 Flashcards
what is the symbol for a reversible reaction
–> <–
what happens in the forward reaction of a reversible reaction
initially the reactants are used up quickly but then slow as their conc. drops
what happenes in the backwards reaction of a reversible reaction
initially reactants are reformed slowly then speed up as the conc. of products increases
what is dynamic equilibrium
rate of forwards reaction equals rate of backwards reaction in a closed system, conc. of each substance remains constant
write a Kc equation for 2A + B –><– 2C + D
[A]^2 [B]
how to calculate units of Kc
cancel out top and bottom of fraction
mol dm^-3
see flash card
invert powers if units under line
what is homogeneous
all reactants and products in same state and all reactants and products in Kc
what is herterogeneous
all reactants and products in different states and dont include solids and pure liquids in Kc
2 NO2 (g) –><– 2NO (g) + O2 (g)
33.2 g NO2 heated in vessel with volume of 9.65 dm^3 at 450 degrees and 6.88g of O2 found in equilibrium mixture
calculate Kc
Initial moles
Change in moles
Equilibrium moles
see flash card
CH3COOH (l) = C2H5OH (l) –><– CH3COOC2H5 (l) +H2O
at equilibrium conc, of ethanoic acid was 1,8 moldm-3 and ethanol was 3.2 moldm-3, Kc is 3.5 calculate conc. of products
see flash card
ans= 4.49 moldm-3
what is total pressure
sum of all pressures of the individual gases (partial pressure)
SO2Cl2 (g) –><– SO2 (g) + Cl2 (g)
at equlilibrium 263 KPa of Cl2, total pressure is 714 KPa
calculate partial pressure of SO2Cl2
188K
see flash card
what is a mole fraction
proportion of gas in a mixture
how to calculate a mole fration
number of moles of gas / total number of moles of gas in the mixture
how to calculate partial pressure from mole fraction
mole fraction of a gas x total pressure in mixture
3 moles of SO2Cl2 heated, eq\uilibrium mixture contains 1.75 moles of Cl2, total pressure = 714KPa , what is the partial pressure of SO2Cl2
SO2Cl2 (g) –><– SO2 (g) + Cl2 (g)
- draw ICE table and write initial moles
- we know we have 1.75 mol Cl2 at equilibrium
- 1:1 ratio so change the same
- mole fractiom of SO2Cl2
1.25/4.75 = o.263 - work out partial pressure
0.263 x 7.14 = 188KPa
write Kp expression for
eE (g) + fF (g) –><– gG (g) + hH (g)
Kp = (pG)^g (pH)^h
——————–
(pE)^e (pF)^f
what is le chateliers principle
if a reaction is at equilibrium and is subjected to a change in pressue, temperature, or concentration, the position of equilibrium will move to counteract change
what happens to the psoition of equilibrium if you increase conc. of reactant and conc. product
increase reactant = shift right, more product
increase product = shift left, less product
what happens to the position of equilibrium is you increase pressure
shift to side with fewest number of gas particles
what happens to the position of equilibrium is you increase temperature and decrease temp
increase = shift in endothermic direction +ve
decrease = shift exothermic -ve
what happens to the position of equilibrium is you add a catalyst
nothing
