Physical Chemistry Exam 1 Prep

Thermodynamics 1,2 and 3 terms and definitions.

What is thermodynamics?

The study of energy transfer during physical, chemical, and biological processes

What is energy?

The capacity to do work

What are the two ways energy can transfer

Work and Heat

Is work organized? T/F type it out

True

Is work random or disorganized? T/F

False

What are the other properites of work… List them.

Moves something against an opposing force, used to accomplish a specific task

Examples of work?

Lifting weights, mujscle movement, building proteins/dna

Is heat disorganized? T/F

True

What is the other property of heat?

Energy transfer due to temperature differences

What can heat do?

Increase reaction rates, break h bonds, denature proteins, decrease enzyme activity.

Exothermic definition

Energy leaves the system as heat

Endothermic definition

Energy enters the system as heat. Surroundings become cold.

Exothermic: Do the surroundings get hotter or colder?

Hotter

Endothermic: Do the surroundings get hotter or colder?

Colder

What is heat’s( q) sign in Exothermic Rxn’s (-) or (+)

-

What is heat’s( q) sign in Endothermic Rxn’s (-) or (+)

+

What is combustion? Looking for reaction type

Exothermic

What is an example of an Endothermic rxn?

Cold pack

Combustion Reactant side:

Organic matter + o2

Combustion Product side:

Co2+ h2o+ energy

Where is energy in an exothermic rxn? What side( products or reactants)

Product

Where is energy in an endothermic rxn? What side( products or reactants)

Reactants

What is the system?

What you are studying

What is the surroundings?

everything around the system

Universe= ( what is it made up of)

system+ surroundings

Open systems have energy and matter? T/F

True

Closed systems have energy and matter? T/F

False

Isolated systems have energy and matter? T/F

False

Closed systems have energy only? T/F

True

Isolated systems have no energy or matter? T/F

True

What is an example of an open system?

A test tube with no stopper and no insulation

What is an example of an closed system?

A test tube with a stopper and no insulation

What is an example of an isolated system?

A test tube with a stopper and insulation

-w= energy leaving the system as work? T/F

True

What are examples of -w?

Expansion, raising a weight

+w= energy leaving the system as work? T/F

False

+w= energy entering the system as work? T/F

True

What are some examples of +w?

Compression, streching a muscle

What is the work against gravity formula:

w=mgh

Mass is measured in what units unless specified

Kg

Is gravity a constant? T/F

True

Height is measured in what unit unless specified?

M

How many J in one KJ?

1,000

1 Cal= how many Jules( look at key if needed)

4.184J

Pressure volume work:

Occurs when a gas expands or compresses against an external pressure

Expansion= - or + w?

-w

Compression = - or + w

+w

How do you find the Δ V?

V final- V initial

n is what term?

moles

How do you calculate Δ n?

n final- n initial

Work may be initially be in what units?

L/atm

Heat Capacity is measured in what unit?

C

Heat Capacity is defined as…

The amount of heat needed to raise an objects temperature by 1 degree C

Units for C?

J/C or J/K

How do you calculate ΔT for temp change?

T final - T initial

Main equation for heat capacity?

q=CΔT

High heat capacity takes more or less heat to change the temperature? ( more or less)

More

Low heat capacity takes more or less heat to change the temperature? ( more or less)

less

Specific heat is measured in what unit?

Cs

Specific heat:

Heat required to raise 1 g of the substance by 1 degree C

Units for Specific heat?

J/(C*g)

Main equation of specific heat?

q=mCsΔT

Molar heat capacity is measured in what unit?

Cm

Molar heat capacity:

Heat required to raise 1 mole of substance by 1 degree C

Main Formula of Molar heat capacity:

q=nCmΔT

Units for molar heat capacity

J/(C*mol)

C is what?

The entire object

Cs is what?

Per gram

Cm is what?

per mole

Why does h20 have a high specific heat?

Hydrogen bonding causes h20 to have a high specific heat. Since it has a high specific heat it will require more heat in order to break the hydrogen bonds.

H can bond to what for hydrogen bonding?

ONF

What happens when heat is added to water?

Heat disrupts/rearranges the H bonds

What does this biologically mean about h2os high heat capacity?

Helps organisms regulate their temperature

High C means what?

more storage, smaller ΔT

Low C means?

less storage, larger ΔT

Temperature:

Tells us how much the particles in a substance are moving

If you increase the temperature what happens to the particles?

Particles move faster

If you decrease the temperature what happens to the particles?

Particles move slower

Molecules store energy:

Store energy in different types of molecular motion

Energy levels:

Different types of molecular motion have different energy level spacings

What is the order starting from the largest to smallest in the energy level differences?

Electronic> Vibrational> Rotational> Translational

Which energy level has the largest gap/ energy level differences?

Electronic

What is the smallest energy level gap/ differences?

Translational

What is NOT part of the motion for biological processes?

Electronic

What are the most important motions for biological molecules?

Vibrational, Translational, Rotational

Do biological molecules have many bonds? T/F

True

Are biological molecules large or small?

Large

Since Biological moleculare are large and have many bonds…

More atoms, more possible motion, more ways to store energy.

Boltzmann Distribution:

Describes how molecules are distributed among available energy levels at a given temperature.

Low temperature occupy which energy levels?

Mostly low energy levels, few molecules at high energy levels

High temperature occupy which energy levels?

More molecules occupy higher energy levels

When the temperature incrreases what happens with the energy levels?

More energy levels become populated

High heat capacity has energy levels closer together or further apart?

Closer

Low heat capacity has energy levels closer together or further apart?

Further

ΔT in high heat capacity is?

Small

ΔT in low heat capacity is?

Large

High heat capacity has more ways to store energy, energy can be stored instead of immediately increasing temp, and has small temp increases. T/F

True

Low heat capacity has less ways to store energy, more energy goes towards increasing the temperature, and has large temp increases. T/F

True

Heat capacity in the body is low or high?

High heat capacity in the body

What produces heat through metabolism?

Cells