u2: constant calculations

Question 1

what can be used to find K eq

Answer 1

• concentration (mol/L)
• pressure of gas

Question 2

when do you use Kc

Answer 2

when all molar concentrations of prod’ts and reactants are known

Question 3

when do you use Kp

Answer 3

when reactants and products of equilibrium are all gases

Question 4

ideal gas law

Answer 4

PV = nRT
- P: pressure
- V: volume (L)
- n: moles
- R: 8.314
- T: temp in K, +273.15

Question 5

how do you get to molar concentration from ideal gas law?

Answer 5

1. rearrange: P/RT = n/V
2. we know M = n/V
3. thus, M = P/RT

Question 6

convert between Kp and Keq equation

Answer 6

Kp = Keq (RT)^∆n

Question 7

change in moles

Answer 7

∆n = (c+d) - (a+b)
- where a, b, c, and d are stoichiometric coeffs

Question 8

wht’s a mole fraction?

Answer 8

• total pressure in system = sum of pressures of each gas
• if given decimal mole fractions, multiply by total pressure to get partial pressures of each

Question 9

when is equilibrium constant a constant ratio?

Answer 9

only when the system is in equilibrium

Question 10

reaction quotient

Answer 10

• Q
• ratio when system not at equilibrium
• if Q = Keq, then rxn at equilibrium

Question 11

when do you use Q vs. Keq

Answer 11

• Q: when system not at equilibrium
• Keq or Kc: when system at equilibrium

Question 12

Q > Keq

Answer 12

• too many products
• equilibrium will shift left

Question 13

Q < Keq

Answer 13

• too many reactants
• equilibrium will shift right