# Energetics Flashcards

1
Q

Enthalpy change

A

Energy change for a reaction at constant pressure

2
Q

Standard Conditions

A

100 kPa at 298K

3
Q

Enthalpy of formation

A

the energy change for the formation of one mole of a substance from it’s elements in their standard states

4
Q

Enthalpy of combustion

A

the energy change when one mole of a substance is completely combusted in oxygen from standard states

5
Q

Enthalpy of solution

A

the energy change when 1 mole of substance is dissolved in a solution

process is known as dissolution

6
Q

How to calculate enthalpy changes in solutions

A

Use an insulator

Calculate the temperature change in K

of a known mass of water (often the total volume of the solutions involved)

7
Q

How to calculate enthalpy changes for fuels

A

Use a calorimeter

Calculate the temperature in K

of a known mass of water

8
Q

Calculating molar enthalpy changes

A

Calculate the energy change

divide by moles used

9
Q

Saturation

A

When no more solute

can be dissolved in a solvent

excess can be filtered off

10
Q

State the names and units for the following

Q= MC T

A

Q= Energy Change

M= Mass of water

C= specific heat capacity of water

T= temperature change in K

11
Q

Calculating energy change per gram

A

Calculate energy change

divide by gramms used

12
Q

Calculating energy change per gram

A

Calculate energy change

divide by grams used

13
Q

Exothermic

A

Reactions that release energy to the surroundings

-ve

14
Q

Endothermic

A

Reactions that take in energy from the surroundings

+ve

15
Q

Activation Energy

A

Minimum energy needed

for a reaction to occur (break bonds)

16
Q

Effect on catalyst on activation energy

A

Reduced

Provided an alternative pathway for reaction

Not used up in the reaction

17
Q

Mean bond enthalpy

A

The average amount of energy required to break one mole of a specific bond in its gaseous state

18
Q

what is a calorimeter used for?

A

used for measuring amount of heat involved in a chemical energy

19
Q

What is Hess’ law?

A

Enthalpy change for a chemical reaction is the same whatever route is taken from reactants to products (it is independent of route).

20
Q

How do you calculate bond enthalpy

A

sum of all the bonds broken minus the sum of all the bonds made