Energy from Chemical Reactions Flashcards

1
Q

In a chemical reaction, what does Einitial refers to? And Efinal?

A

The internal energy of the reactants.

The internal energy of the products.

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2
Q

How is energy transferred between the system and the surroundings?

A

As heat or work

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3
Q

if the system is heating up, what is happening to the surroundings?

A

They are heating down

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4
Q

What does it mean that a system had work done on it?

A

That the system is compressed

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5
Q

System expansion is…

A

Negative

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6
Q

System compression is…

A

Positive

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7
Q

Work done by or on a system that expands or contracts is what?

A

Mechanical work due to the change in volume of the system.

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8
Q

If the system expands against the atmosphere then…

A

Work is done by the system

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9
Q

If the system contracts due to pressure from the atmosphere

A

Work is done on the system

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10
Q

If there is no change in volume then…

A

No work is being done

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11
Q

What do we call the work done by the expansion and contraction of gases?

A

Pressure-volume work

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12
Q

When heat moves into a system (q+), it is called

A

Endothermic process. Ex: Melting Ice

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13
Q

When heat moves out of a system (q-), it is called

A

Exothermic process. Ex: Combustion of propane

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14
Q

What is it called the measurement of heat flow?

A

Calorimetry

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15
Q

What is a calorimeter?

A

The device used to measure heat flow

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16
Q

What is the heat capacity of a substance?

A

It is the amount of heat that it takes to raise the temperature of something 1 degree Celsius or 1K.

17
Q

The larger the heat capacity…

A

The more heat it takes to raise the temperature.

18
Q

For pure substances we measure the…

A

Molar heat capacity

19
Q

Enthalpy and enthalpy changes are

A

State functions

20
Q

If during a chemical reaction, the system loses energy to the surroundings and the system expands against the surroundings, are q and w being positive or negative?

A

Both are negative because the system loses energy to the surroundings, and because there is work being done by the system on the surroundings.