Day 6 (Jan 11) Notes

Question 1

Exothermic Reactions

Answer 1

if energy is given off the reaction is said to be exothermic. Exothermic reactions feel hot.

reactants have more energy than products
ΔH= negative

Question 2

Endothermic Reactions

Answer 2

If energy is taken in the reaction is said to be endothermic. endothermic reactions feel cold.

reactants have less energy than the products.
ΔH= positive

Question 3

Hess’s Law

Answer 3

All chemical bonds have energy associated with them. when bonds form energy is given off. When bonds break energy is taken in.

Question 4

Since we cannot mensure energy in a substance we need a reference point in order to compare bond energres.
Overall changes can be calenlated butt energy of particular bonds cannot be calculated.
All elements in their standard state are assigned ero energy

Question 5

Enthalpy (H)

Answer 5

the total amount of energy contained by an substance or group of substances
H= the energy involved in a reaction

Question 6

There are a number of ways to calculate change in enthalpy

Answer 6

If H= negative the reaction is exothermic
If H= positive the reaction is endothermic