Entropy

Shell Wood
Flashcards by Shell Wood, updated more than 1 year ago
Shell Wood
Created by Shell Wood about 8 years ago
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A-Levels thermodynamics Flashcards on Entropy, created by Shell Wood on 05/26/2013.

Resource summary

Question Answer
What happens to the temp increase when a solid transitions into a liquid? The temp remains the same until the transition is complete. ΔHfusion = energy to melt
What is ΔH? Enthalpy change
what is Δs? change in entropy
How do you work out the Δs? Δs = Ʃ products - Ʃ reactants Ʃ = sum of
what is more likely to disperse energy 1) gas 2) solid 1) Gas
What is this ΔG = ΔH - TΔs Gibbs law to work out the feasibility of a reaction occuring
Is this reaction feasible ΔG = +ve value Explain your answer No Value has to be 0 or lower for a reaction to be feasible.
Is this reaction feasible ΔG = -ve value Explain your answer Yes Value is lower than 0 so is feasible to suggest it will work
Explain what the terms mean ΔG = ΔH - TΔs ΔG = Gibbs law - feasibility of reaction ΔH= Enthalpy change T = Temp of reaction in Kelvin Δs = Change in entropy
Is an endothermic reaction likely to be feasible? Explain your answer NO Likely to give a positive ΔG value as it takes in more energy than it releases. This means it is not very good at dispersing energy
Is an exothermic reaction likely to be feasible? Explain your answer Yes Likely to give a negative ΔG value. Exothermic reactions give out more energy than they take in and so are good at dispersing energy.
what does ΔG = O mean? Reaction is at equilibrium reaction is feasible
What are the units for a ΔG value? J mol-1 K-1
Define Entropy The entropy of a substance at a temp is a measure of the total amount of energy that had to be a dispersed within the substance.
If energy is added to the following systems how can it be dispersed. 1) atom 2) molecule 3) bonds 1) An atom can disperse energy by promoting electrons to higher enrgy orbitals. 2) Molecules can move more and faster. 3) bonds can vibrate.
What is the value of absolute 0 in kelvin? - 273
Why does more energy have to be added a gas to raise the temperature 1 degree than for a solid? 1) Gas particles are already energised and moving around. 2) More energy is being dispersed by the gas so more has to be added. 3) Solids can't move well and so disperse energy less causing faster temp increases
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