14.3
When can you neglect x in equilibrium?
if the change (x) is small compared to any initial concentration
whats the difference between Kc and Kp?
Kc is the equilibrium constant given as a ratio between concentrations of products and reactants while Kp is the equilibrium constant given as a ratio between the pressure of products and reactants
what is Le Châtelier's principle ?
it states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to reestablish an equilibrium
what is daltons law of partial pressure?
the total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual component gases
What's a buffer?
the equilibrium concentrations are [Br2] = 2.3 x 10–3 M, [Cl2] = 1.2 x 10–2 M, [BrCl] = 1.4 x 10–2 M. Write the equilibrium expression and calculate Kc for this reaction.
Kc = [BrCl]2 /[Br2][Cl2]
(1.4 ⇥ 102)2 (2.3 ⇥ 103)(1.2 ⇥ 102) = 7.1
if K>1 reaction 1 product or reactant favored ?
the reaction is product favored
if the pressure increases which way would the reaction shift?
the equilibrium will shift to the side where their is less moles in order to reestablish equilibrium
What is the total pressure of a mixture of oxygen and helium if they were 0.20 atm and 25.0 atm respectively
P total = p oxygen + P helium
P total = 25.2 atm
when is a buffer at max capacity?
when the concentration of the weak acid and its salt or weak base and its salt are equal
for example: 0.5 M carbonate and 0.5 M bicarbonate ions
Given that the concentration of CL2 and PCl3 is 0.40 find K eq At equilibrium knowing that the concentration of PCl5 is 0.224
I 0.40 0.40 0
C -0.224 -0.224 +0.224
E 0.156 0.156 0.156
Keq= [0.224] / [0.156] [0.156] = 9.20
If reaction (1) K=1 x 10^8 and Reaction (2) K=1 x 10 ^6
Can we conclude which one is faster ?
No, we cannot the value of K and the time it takes for the reaction to take place are not directly related
in a exothermic reaction what would happen if the tempreture increases
the reaction will shift left to make more products in order to reestablish equilibrium, since Q>K
The total pressure of that sample was 5.00 atm and at that same temperature the pressure of the water vapor wass 0.50 atm what would the partial pressure of the hydrogen gas be?
Pressure H = P water vapor - P total
Pressure H = 5.00 - 0.50 = 4.50 atm
Would 100ml of 1.0M of HCL + 5-ml of 1.0M of NAOH be a max buffer ?
No since Buffers cannot be made from a strong acid and a strong base, This is because they ionize completely and if they are added in equal amounts they will neutralize eachother
consider the reaction 2NO2(g) ←> N2O4 (g) Kc= 1.15 where The concentration of NO2 = 0.05 find the concentration of the products
I .05 0
C -2x +x
E 0.05 +x
1.15= x / 0.05
x= 2.9 x 10^-3
do coiefficeints affect the equilibrium expression
yes
K= [C]^c [B]^b / [A]^a [D]^d
what would happen if you added reactants to the reaction
the reaction will shift right to make more products in order for Q to get closer and closer to K
The mole fraction of oxygen is 0.147 calculate the partial pressure of oxygen if the atmospheric pressure is 760 Torr
P oxygen = ( X oxygen)(P total)
(0.147)(760)
Pressure of oxygen = 593 Torr = 0.8 atm
Calculate the mass of ammonium, chloride needed to buffer 250ml of 2.0M to a ph of 10.00( ka= 5.5 x 10^-10)
pH = pKₐ + log([A⁻]/[HA]).
10.00= 5.5 x 10^-10 + log(2.0/ammonium)
Concentration of ammonium needed= 0.36 M
Cl2 gas undergoes homolytic cleavage into chlorine atoms at 1100.Kp is 1.13 x 10-4. If a sample with an initial Cl2 gas pressure of 0.500 atm reached equilibrium, what is the total pressure in the flask?
I 0.5 0
C -x +2x
E 0.50 -x +2x
1.13 x 10-4 = 2x2/0.50 therefore x= 3.7 x 10-3
0.500 - 3.74x10-3+ 2(3.74x10-3) = 0.504atm
Does Kc change with a change in concentration?
The equilibrium concentrations of reactants and products may vary, but the value for Kc remains the same, because the ratios stay constant
if Q<K which direction will the reaction shift
The reation will shift right and make more products inorder to restablish equilibrium
If a gas is collected over water, what corrections need to be made when calculating the volume of the dry gas at STP?
The pressure of the gas collected can be calculated by subtracting the pressure of the water vapor from the total pressure
What makes a buffer ineffective