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CHEM114 > Thermodynamics Block 3 > Flashcards

Thermodynamics Block 3 Flashcards

1
Q

What is thermodynamics?

A

Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy.

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2
Q

Define heat.

A

The energy transferred due to a temperature difference.

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3
Q

Define work.

A

Depends of pressure and volume can increase pressure, volume or both.

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4
Q

Define temperature.

A

A measure of the average kinetic energy of particles in a system.

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5
Q

Define energy.

A

Something has energy if it has the capacity to do work or to produce heat (or both). After doing work or producing heat, it has less energy

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6
Q

What is the first law of themrodynamics

A

Energy can be converted from one form to another, but it cannot be created or destroyed. Also called the law of conservation of energy.

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7
Q

When did the study of thermodynamics begin?

A

In the early 1800s due to the industrial period.

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8
Q

What can heat tell us?

A

About making and breaking chemical bonds.

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9
Q

Greater kinetic energy = what?

A

The more particles will move around.

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10
Q

Difference between temperature and heat?

A

Heat and temperature are related to each other, but are different concepts. Heat is the total energy of molecular motion in a substance while temperature is a measure of the average energy of molecular motion in a substance. temperature does not depend on the size or type of object.

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11
Q

What are the units for temperature?

A

Celsius, or Kelvin temp scale

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12
Q

True or False, The size of Kelvin and Celsius are the same.

A

True!

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13
Q

Define the system.

A

The object or collection of objects that is being studied

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14
Q

Define the surroundings.

A

Everything outside the system that can exchange energy with the system.

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15
Q

What is the unit for energy?

A

Joule (J) we usually use Kilo Joules which is 1000 Joules. The old unit was calories (Cal)

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16
Q

What is the symbol for heat?

A

q and the unit is J Joules

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17
Q

What does exothermic mean?

A

When heat is transferred from the system to the surroundings. q(system) is -ve and q(surroundings) is +ve

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18
Q

What does endothermic mean?

A

When heat is transferred from the surroundings to the system. q(system) is +ve and q(surroundings) is -ve

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19
Q

Is melting ice exothermic or endothermic?

A

Endothermic.

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20
Q

Is freezing water exothermic or endothermic?

A

Exothermic

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21
Q

Is setting concrete exothermic or endothermic?

A

Exothermic

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22
Q

Is dissolving NaCl in water endothermic or exothermic? (Conc solution gets cold)

A

Endothermic

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23
Q

Is dissolving LiCl in water endothermic or exothermic? (Conc solution gets hot)

A

Exothermic

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24
Q

Is iron rusting endothermic or exothermic?

A

Exothermic

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25
Q

What is heat capacity?

A

The ratio of the heat energy absorbed by a substance to its increase in temperature.

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26
Q

What does delta T stand for?

A

Temperature change. Final - initial temperature

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27
Q

What does Cs stand for?

A

The specific heat capacity of a material.

28
Q

What is specific heat capacity?

A

The heat required to raise the temperature of the unit mass of a given substance by a given amount (usually one degree). 1g by 1K or 1C

29
Q

What is the heat of fusion?

A

The enthalpy of fusion of a substance, also known as heat of fusion is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid, at constant pressure.

30
Q

What is the heat of vaporisation?

A

The heat of vaporization is defined as the amount of heat needed to turn one gram of a liquid into a vapor, without a rise in the temperature of the liquid.

31
Q

What is the heat of sublimation?

A

The molar heat (or enthalpy) of sublimation is the amount of energy that must be added to a mole of solid at constant pressure to turn it directly into a gas (without passing through the liquid phase).

32
Q

What are extensive properties?

A

Extensive property is a property that changes when the amount of matter in a sample changes. Examples are mass, volume, length, and charge.

33
Q

What are intensive properties?

A

An intensive property is a property of matter that depends only on the type of matter in a sample and not on the amount. Color, temperature, and solubility are examples of intensive properties.

34
Q

What is hess’s law?

A

The Hess’ law states that the change of enthalpy in a chemical reaction (i.e. the heat of reaction at constant pressure) is independent of the pathway between the initial and final states.

35
Q

True or False? Water has a low specific heat capacity.

A

False, water as a high specific heat capacity

36
Q

What does it mean by water has a high specific heat capacity?

A

It is harder to raise its temperature.

37
Q

True or False? Metals have high heat capacities.

A

False, metals have low heat capacities.

38
Q

Why does water have a high heat capacity?

A

Hydrogen bonds

39
Q

Why is it important our oceans are made up as water?

A

Due to its high heat capacity because its better at keeping the ocean an average temperature.

40
Q

What is a calorimeter?

A

an apparatus for measuring the amount of heat involved in a chemical reaction or other process.

41
Q

What is Enthalpy?

A

A state function. Symbol: H. When a substance changes at constant pressure, enthalpy tells how much heat and work was added or removed from the substance.

42
Q

What is the difference between enthalpy and heat?

A

Enthalpy is heat at constant pressure.

43
Q

What is a state function?

A

Where initial and final states are important but its not important how you got there.

44
Q

What is the symbol for changes in enthalpy?

A

Delta H

45
Q

Is distance traveled a state function?

A

No

46
Q

What is delta H for an exothermic reaction?

A

<0

47
Q

What is delta H for an endothermic reaction?

A

> 0

48
Q

What are standard thermodynamic conditions?

A

The reactants and products at a a pressure of 1 bar. Or.a concentration of 1molL-1. There is not set temperature but if no temperature is given assume 298L (25c)

49
Q

What is the calculation for heat transferred?

A

q = Cs x m x delta T

50
Q

What does Cs stand for?

A

The specific heat capacity of a material

51
Q

What does m stand for?

A

Mass

52
Q

What does delta T stand for?

A

Change in temperature

53
Q

What does q stand for?

A

The amount of heat transferred

54
Q

What does the specific heat capacity determine?

A

How hot a material will get for a given amount of heat and their “Heat Holding” ability.

55
Q

Does water have a high or low specific heat capacity?

A

High!

56
Q

Do metals have a high or low specific heat capacity?

A

Low

57
Q

Putting heat into a system does what?

A

Makes the molecules and atoms move faster and when they move fast enough inter or intra molecular bonds can be broken

58
Q

Is the stretching/compressing or breaking of bonds exo or endothermic?

A

Endothermic

59
Q

Is the formation of bonds exo or endothermic?

A

Exothermic

60
Q

What is delta rH?

A

The standard enthalpy change i.e for the reaction under standard thermodynamic conditions.

61
Q

What is delta fH?

A

The Standard Molar Enthalpy of Formation. delta fH
is the enthalpy change at 298 K for the formation of 1 mol of a compound directly from its component elements in their standard states.

62
Q

Are most delta fH values positive or negative?

A

Negative

63
Q

How do you use delta fH to calculate delta H for a reaction?

A

delta H = ΣνpDfH°(products) – ΣνrDfH°(reactants). (Sum of all the standard enthalpy of formation changes of the products) - (Sum of all the standard enthalpy of formation changes of the reactants)

64
Q

What is v?

A

The stoichiometric coefficient (The number of moles of a reactant or product in the balances equation)

65
Q

Delta fH is zero for what?

A

An element in its standard state.

66
Q

What is Dissolution?

A

Typically, this involves a solid going into a liquid phase, but dissolution can involve other transformations as well.

67
Q

What is crystallisation?

A

Crystallisation is the process by which a solid forms, where the atoms or molecules are highly organized into a structure known as a crystal.

CHEM114 (16 decks)

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