Chem Chapter 7-8

Energy and phase changes

Energy

ability to do work

Metabolism

chemical reaction in cells and provide energy

Joule (j)

unit of heat and work

calorie (cal)

unit of energy

1 cal = ? j

4.184 j

which one is bigger? Calorie or calorie

Calorie

1 Calorie = ? kcal

1 kcal

True or false? Calorie and kilocalorie are the same thing

True

Temperature

measurement of how hot and cold an object is

Heat

flow of thermal energy between objects with different temperature

True or false? Temperature is also kinetic energy

True

Kinetic energy

measures average amount of energy of motion

Heat transfer equation

heat = mc(delta T)

Specific heat is a...

characteristic

Specific heat is reported as unit of

cal/g(c) or cal/g(k)

If delta T is positive what does that tell about the direction of heat flow

Heat goes into an object

If delta T is negative what does that tell about the direction of heat flow

Heat goes out of an object

Gas/Liquid/Solid? A lot of energy in molecules

Gas

Gas/Liquid/Solid? Have enough energy for atoms to shift around

Liquid

Gas/Liquid/Solid? Doesn't have enough energy to have atoms move because it is at a fixed state

Solid

Endothermic

heat is added to a substance

Exothermic

heat is removed from a substance and released to surroundings

Endo/Exothermic? Ice melting from the sun

Endothermic

Endo/Exothermic? Fireplace emitting heat

Exothermic

Heat of fusion

amount of heat/g or mol needed for a phase change that happens at the melting point

Heat of vaporization

amount of heat/g or mol needed for a phase change that happens at boiling point

Endo/Exothermic? Heat is a reactant

Endothermic

Endo/Exothermic? Heat is a product

Exothermic

Endo/Exothermic? delta H is positive

Endothermic

Endo/Exothermic? delta H is negative

Exothermic

Endo/Exothermic? Uphill trend

Endothermic

Endo/Exothermic? Downhill trend

Exothermic

Endo/Exothermic? Bonds broken in reactants are stronger than bonds formed in products

Endothermic

Endo/Exothermic? Bond formed in the products are stronger than the bonds broken in reactants

Exothermic

Endo/Exothermic? Products are lower in energy than reactants

Exothermic

Endo/Exothermic? Reactants are lower energy than products

Endothermic

Kinetic Molecular Theory of Gas

Gas have tiny particles that are constantly moving, the higher the temperature the faster the movement, no reactions with each other

Units for pressure (2 common ones)

atm, mmHg

Boyle's Law

P1V1=P2V2

Charles Law

V1/T1=V2/T2

Combined Gas Law

P1V1/T1=P2V2/T2

Ideal Gas Law

PV=nRT

All temperatures in gas laws must be converted to... first

Kelvin

Standard Temperature & Pressure

273K, 1 atm

STP volume is

22.4L/mol

Partial Pressure

each gas is independent in a mixture

How to find pressure of gas?

Sum of partial pressure

Henry's Law

Higher the pressure of gas above a liquid means a higher concentration of the gas in the liquid

Henry's Law equation

C=kPgas

Melting point separates what two phases

solid and liquid

Boiling point separates what two phases

liquid and gas

What depends on Intermolecular Forces

boiling and melting point

Weakest to Strong intermolecular forces (4)

London Dispersion Force, Dipole-Dipole, Hydrogen Bond, Ionic

Intramolecular Forces

attraction between atoms

Intermolecular Forces

attraction between molecules

Inter/Intra? Strongest molecular force

Intra

London Dispersion Force

weakest, sets up a temporary separation of charge that disappears immediately

True or False? All molecules experience dispersion force cause by electrons being in different places in a molecule at any one time

True

What forms dispersion force?

Larger atoms with many valance electrons are less tightly held together and result in attraction

Can dispersion force be strong? Explain how

Yes, if there are many dispersion forces it will support an attraction

Dipole-Dipole Force/Attraction

attraction between positive and negative ends of a polar molecule

Polar/Nonpolar? Dispersion

Nonpolar

Polar/Nonpolar? Dipole-Dipole

Polar

Hydrogen bonding (stronger type of what bond?)

hydrogen atoms bonded to electronegative atoms causes a strong type of dipole-dipole attraction

Which atoms can bind with hydrogen for hydrogen bonding to happen? (hold the phone)

O, N, F

Ex of hydrogen bonding

DNA chains

Ionic bonding

attraction to charges

Boiling point

strength of attractive intermolecular forces exhibited by the individual molecule

True of False? Ionic Bonding requires less heat for the bond to break

False