5 - Chemical Energetics Flashcards
What happens when a bond if formed or broken
energy is released or absorbed
What is the cooling curve? Explain using exothermic reactions
see card
exothermic reactions : energy is released , increasing temperature and stopping cooling process
What kind of reaction is it :
Ca CO3(S) ————> CaO+CO2(g)
see card
endothermic (decomposition of calcium carbonate)
Melting : endo or exothermic ?
endo
boiling : endo or exothermic ?
endo
condensing : endo or exothermic ?
exo
freezing : endo or exothermic ?
exo
Subliming : endo or exothermic ?
endo
depositing : endo or exothermic ?
exo
Define Activation energy
What is its symbol?
The minimum energy needed for a reaction as particules collide
Ea
Give 2 examples of exothermic reaction
Combustion
Neutralisation (of an acid)
Give 2 examples of endothermic reaction
Electrolysis
Melting
Draw/identify an advanced Reaction pathway diagram
label :
- energy
- progress of reaction
- reactions
- energy/ enthalpy change
- products
- activation energy
How does activation energy affect a reaction?
If low - reaction is fast
If high - reaction is slow
Define Enthalpy
The amount of energy required to break bonds.
Different bonds have different strengths, and so have different bond enthalpies
How do you find the enthalpy charge (∆H) ?
Energy needed to break bond — energy released in making of bonds
+ = endothermic
- = exothermic
What happens to the bonds?
reactions ——> Atoms ——> products
- bonds broken, endothermic
- bond made, exothermic
What does ∆H represent?
Overall energy charge/ enthalpy charge
Define endothermic reaction
endothermic reaction absorbes thermal energy from the surrounding, leading to a decrease in the temperature of the surrounding
Define exothermic reaction
Exothermic reactions release thermal energy to the surroundings, leading to an increase in the temperature of the surroundings
What are the conditions required for a reaction to occur?
When sufficient particles collide, with sufficient energy to react
If particles don’t have enough energy, they simply bounce off each other
