13423770
Description
Flashcards by I Shouldn't be awake, updated more than 1 year ago
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Created by I Shouldn't be awake
over 6 years ago
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| Question | Answer |
| What is H? | Heat energy of a system |
| ΔH= | H(products) - H(reactants) |
| ΔfHϴ | ΔH When 1 MOLE compound formed from elements under ϴ |
| ΔfHϴ of an element | 0 |
| ΔcHϴ | One mole compound completely reacted w/ O2 under ϴ |
| ΔneutHϴ | Acid+Base = 1 MOLE H2O under ϴ |
| Effect of doubling vol. in ΔneutHϴ on T change | Double T = double E however spread over twice the volume so no change |
| How is ΔrHϴ determined from q? | q = E gained by surroundings So ΔrHϴ must be the opposite |
| What is m in reaction btw. 2 solutions? | Solution itself is the immediate surroundings So M of both |
| What is C? | 'C needed to ^ 1g substance by 1K |
| Inaccuracies w/ experimental ΔcHϴ (3) | Incomplete combustion as CO or Soot Evaporation of methanol on wick Heat loss to surounding other than water |
| Δ btw. experimental and databook | Experimental less exothermic due to less efficient energy transfer |
| How to increase accuracy (2) | Use a draught screen could minimise erros of heat loss Input O2 gas ensure complete combustion |
| Proving that a reactant is in excess in ΔrHϴ | Calculate n of limiting reagant This gives you n of excess required Calculate actual n of excess |
| Calculating ΔrH from bond enthalpies | ΔrH=ΣH(r) - ΣH(p) |
| What conditions are required when working out these reactions? | All species must be gaseous, therefore it can't be standard if say H2O is involved. Can still work out the standard, but would need to account for ΔrH of H2O(g) -> H2O(l) |
| What is average bond enthalpy | E required to break 1 mole of bonds in a gaseous molecule |
| What is DeltarH from formation? | P-R |
| What's enthalpy change of reaction from combustion? | R-P |
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