Energetics - Chapter 4 Flashcards

1
Q

What is an exothermic reaction

A

A reaction that gives out energy from the surrondings

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2
Q

What is an endothermic reaction

A

A reaction which takes energy in from the surrondings

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3
Q

What type of reaction is breaking bonds

A

Endothermic

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4
Q

What type of reaction is forming bonds

A

Exothermic

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5
Q

What is energetics

A

It is the study of heat changes during chemical reactions

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6
Q

What is temperature

A

It is a measure of the average kinetic energy of the particles in a system

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7
Q

What is heat

A

It is a measure of the total energy of all particles present in a given amount of a substance
Measured in KJ/mol

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8
Q

What is an enthalpy change

A

It is when we measure a heat change at constant pressure

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9
Q

What is a standard enthalpy change

A

It is the heat change measured under standard conditions ( 100,000Pa and a stated temperature) with all reactants and products in their standard states

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10
Q

What is standard enthalpy of combustion

A

This is the enthalpy change when one mole of an element or compound is completely burned in oxygen under standard conditions with all reactants and products in their standard states

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11
Q

What is standard enthalpy of formation

A

This is the enthalpy change when one mole of a compound is formed from its elements under standard conditions with all reactants and products in their standard states

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12
Q

What is the enthalpy of formation for any element

A

0

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13
Q

What is the equation for the heat energy change

A

q = M x C x Change in Temp

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14
Q

What technique is used to measure enthalpy change

A

Calorimetry

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15
Q

What is the first law of thermodynamics

A

Energy cannot be created or destroyed, only converted from one form to another

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16
Q

What is Hess’s Law

A

The enthalpy change at constant pressure in a reaction is independent of the route / path taken (and depends only on the initial and final states)

17
Q

What is the equation for enthalpy change

A

Total enthalpy’s of formation of products – Total enthalpy’s of formation of reactants
This can also be used for combustion data

18
Q

What is the bond dissociation enthalpy

A

The enthalpy required to break a particular covalent bond in a molecule when all species are in a gaseous state

19
Q

What is the mean bond enthalpy

A

It is the average value of the bond dissociation enthalpy of a particular type of bond in a range of different compounds