equations Flashcards
(24 cards)
Q: What is the equation for moles when using mass?
Moles = mass / molar mass (n = m / M)
Q: What is the equation for moles when using concentration and volume?
Moles = concentration × volume (n = c × V in dm³)
Q: How do you convert cm³ to dm³?
Divide by 1000 (cm³ ÷ 1000)
Q: What is the ideal gas equation?
pV = nRT
Q: In the ideal gas equation, what are the units for pressure?
Pascals (Pa)
Q: In the ideal gas equation, what are the units for volume?
m³ (cubic metres)
Q: What is the value of the gas constant R?
8.31 J mol⁻¹ K⁻¹
Q: What is the equation for percentage yield?
% yield = (actual yield / theoretical yield) × 100
Q: What is the equation for atom economy?
Atom economy = (mass of desired product / total mass of reactants) × 100
Q: How do you calculate empirical formula?
Divide each element’s mass or % by its Ar, then divide by the smallest value
Q: What is the general equation for enthalpy change using bond enthalpies?
ΔH = Σ(bond enthalpies of reactants) − Σ(bond enthalpies of products)
Q: What is the equation for q in calorimetry?
q = mcΔT
Q: In q = mcΔT, what is ‘m’?
Mass of the solution in grams
Q: In q = mcΔT, what is ‘c’?
Specific heat capacity (usually 4.18 J g⁻¹ K⁻¹ for water)
Q: What is the equation linking enthalpy change per mole?
ΔH = q / n
Q: What is the expression for Kc?
Kc = [products]ⁿ / [reactants]ⁿ (for a given balanced equation)
Q: What is the unit of Kc?
Depends on the number of moles in the balanced equation
Q: What is the expression for Kp?
Kp = (P_products)ⁿ / (P_reactants)ⁿ
Q: In Kp, what are the units of pressure?
Typically atmospheres (atm) or Pascals (Pa)
Q: How do you calculate rate of reaction from a concentration-time graph?
Rate = gradient (Δy / Δx)
Q: What is the units of the rate constant k?
Depends on the overall order of the reaction
Q: How do you calculate percentage uncertainty?
(uncertainty / measured value) × 100
Q: How do you calculate total uncertainty in a titration?
Add individual uncertainties from burette readings
Q: What is the general ionic equation for a neutralisation reaction?
H⁺(aq) + OH⁻(aq) → H₂O(l)
