F325 4

Card Set Information

Author:
JustinL
ID:
266392
Filename:
F325 4
Updated:
2014-03-14 15:18:24
Tags:
Chemistry
Folders:

Description:
OCR A
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user JustinL on FreezingBlue Flashcards. What would you like to do?


  1. What is the standard enthaply of formation?
    • The enthalpy change that takes place when one mole of a compound is formed from it's constituent elements in their standard states under standard conditions
  2. What is the standard enthalpy change of atomisation?
    • The enthalpy change that takes place when one mole of gaseous ions forms from the element in it's standard state.
  3. What is the the standard lattice enthalpy?
    • The enthalpy change that takes place when one mole of an ionic compound is formed from its gaseous ions under standard conditions.
  4. How does ionic charge affect lattice enthalpy?
    • Higher charge means greater charge density.
    • eg. Na+ and Mg2+.
    • Means the lattice enthalpy is more negative.
    • = stronger bonds formed.
  5. How does ionic size affect lattice enthalpy?
    • Smaller the ion means greater attraction between ions.
    • Smaller ions attract more strongly because their charge density is higher.
  6. Define a buffer solution.
    • A solution that resists changes in pH when small amounts of acid or alkali are added.
    • Works because of shifts in equilibreum.
  7. How does a buffer solution resist change in pH if a small amount of acid is added?
    [H+] increases.
    • Most of the H+ ions combine with the weak acid ion A- from the weak acid salt.
    • To form HA
    • This shifts the equilibreum to the left reducing the [H+] to close to it's original value.
    • Restoring pH
  8. How does a buffer solution resist change in pH if a small amount of alkali is added?
    • Most of the OH- ions react with H+ ions from the weak acid to form water.
    • Causes more HA ions to dissociate to form H+ ions.
    • The equilibreum shifts to the right meaning there is little change in [H+].
    • So the pH is restored.
  9. What the standard cell potentialbetween Cu and Zn be?
    Cu2+(aq) + 2e- ⇌ Cu (s) =0.34
    Zn2+ +2e- ⇌ Zn(s) = -0.76
    • Biggest minus smallest.
    • 0.34 --0.76 = 1.10
  10. What would the metal ion half cell look like between Cu and Ag?
  11. How is the hydrogen stored for a fuel cell?
    • Liquid under pressure.
    • Adsorbed on the surface of a solid metal.
    • Absorbed within a solid material.
  12. What is the overall reaction that takes place in a fuel cell?
    H2 (g)+ 1/2 O2 (g) → H2O (l)
  13. What is the reaction that takes place at the negative terminal of a hydrogen fuel cell?
    • H2(g) + 2OH-(aq) → H2O (l) + 2e- 
    • Most negative 
  14. What is the reaction that takes place at the positive terminal of a hydrogen fuel cell?
    1/2O2(g) + H2O(l) +2e- → 2OH- (aq) 

    Most positive 
  15. For a reaction to be feasible what must  be?
    Less than 0 
  16. What is the equation for  ?
    •  being the enthalpy.
    •  being the temperature in Kelvin. 
    •  being the enthalpy change of the system ( Sproducts - Sreactants ) 
    • Units are kJmol-1

What would you like to do?

Home > Flashcards > Print Preview