Energy calculations Flashcards
1
Q
What is an exothermic reaction?
A
A chemical reaction that releases heat to its environment.
It will have a negative HΔ value
2
Q
What is an endothermic reaction?
A
A chemical reaction that absorbs heat from its environment.
It will have a positive HΔ value
3
Q
What are SLC conditions? (5)
A
- temp 25°C
- 1 mol substance involved
- concentrations of 1M
- heat released/ absorbed= kj
- pressure 100 kpa
4
Q
What is enthalpy?
A
Total energy stored in a substance. It can’t be directly measured so a change in heat is used to so the change in enthalpy.
5
Q
What is the enthalpy equation?
A
HΔ= H products - H reactants
6
Q
What are the key features of a thermochemical equation?
A
- if coefficient is doubled so it ΔH
- if reaction is reversed ΔH sign changes
- coefficient=mol ΔH=kj
- +ve/-ve ΔH indicates weather endo/ exothermic
7
Q
What is gas pressure?
A
Particles exert a force by colliding with walls of container. Each collision adds to all others creating a continuous force called pressure.
