5 - Chemical Energetics Flashcards

1
Q

What happens when a bond if formed or broken

A

energy is released or absorbed

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2
Q

What is the cooling curve? Explain using exothermic reactions

A

see card
exothermic reactions : energy is released , increasing temperature and stopping cooling process

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3
Q

What kind of reaction is it :

Ca CO3(S) ————> CaO+CO2(g)

A

see card
endothermic (decomposition of calcium carbonate)

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4
Q

Melting : endo or exothermic ?

A

endo

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5
Q

boiling : endo or exothermic ?

A

endo

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6
Q

condensing : endo or exothermic ?

A

exo

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7
Q

freezing : endo or exothermic ?

A

exo

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8
Q

Subliming : endo or exothermic ?

A

endo

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9
Q

depositing : endo or exothermic ?

A

exo

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10
Q

Define Activation energy
What is its symbol?

A

The minimum energy needed for a reaction as particules collide

Ea

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11
Q

Give 2 examples of exothermic reaction

A

Combustion
Neutralisation (of an acid)

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12
Q

Give 2 examples of endothermic reaction

A

Electrolysis
Melting

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13
Q

Draw/identify an advanced Reaction pathway diagram

A

label :
- energy
- progress of reaction
- reactions
- energy/ enthalpy change
- products
- activation energy

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14
Q

How does activation energy affect a reaction?

A

If low - reaction is fast
If high - reaction is slow

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15
Q

Define Enthalpy

A

The amount of energy required to break bonds.
Different bonds have different strengths, and so have different bond enthalpies

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16
Q

How do you find the enthalpy charge (∆H) ?

A

Energy needed to break bond — energy released in making of bonds

+ = endothermic
- = exothermic

17
Q

What happens to the bonds?
reactions ——> Atoms ——> products

A
  1. bonds broken, endothermic
  2. bond made, exothermic
18
Q

What does ∆H represent?

A

Overall energy charge/ enthalpy charge

19
Q

Define endothermic reaction

A

endothermic reaction absorbes thermal energy from the surrounding, leading to a decrease in the temperature of the surrounding

20
Q

Define exothermic reaction

A

Exothermic reactions release thermal energy to the surroundings, leading to an increase in the temperature of the surroundings

21
Q

What are the conditions required for a reaction to occur?

A

When sufficient particles collide, with sufficient energy to react

If particles don’t have enough energy, they simply bounce off each other