Energetics Flashcards

1
Q

State what s meant by enthalpy

A

The energy content of a substance measured at constant pressure

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2
Q

Exothermic reactions have a positive or negative enthalpy change?

A

Negative

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3
Q

State what is meant by enthalpy change of formation

A

The enthalpy change when one mole of a substance is made from its constituent elements with all products and reactants in their standard states under standard conditions

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4
Q

State what is meant by enthalpy change of combustion

A

The enthalpy change when one mole of a substance is burned completely in oxygen with all reactants and products in their standard states under standard conditions

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5
Q

How do you work out enthalpy?

A

q/mol

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6
Q

State what is meant by specific heat capacity

A

The energy needed to raise the temp. of 1g of a substance by 1*C

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7
Q

What is the equation to work out energy from specific heat capacity?

A
q = m x c x ^T
energy = mass x specific heat x temp.change
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8
Q

State what is meant by mean bond enthalpy

A

The average heat needed when one mole of covalent bonds are broken measured in the gaseous state at 298K and 100kPa

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9
Q

What does Hess’s law state?

A

Enthalpy change for reactions is the same regardless of the rate or route taken

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