Chemistry 1302b Final Exam Questions with 100% accurate solutions (A+ GRADED )

pressure of gas

the force that the gas exerts on the walls of its container as a result of collisions with container walls

ideal gas assumptions

pressure not too high

temp not close to condensation temp

atoms or molecules have no volume

no forces between atoms or molecules

Boyle's law

volume is inversely proportional to pressure

boyle's law formula

P1V1=P2V2

charles law

volume directly proportional to temperature (in K)

charles law formula

V1/T1=V2/T2

charles law combined with boyle's law

P1V1/T1= P2V2/T2

Avogardo's Law

equal volumes of gases at the same temperature and pressure contain equal numbers of molecules

Avogardo's Law formula

V1/n1 = V2/n2

ideal gas law

PV=nRT

In the same volume of different gases, what happens with moles

same number of moles

density

mass/volume

mass (from molar mass)

molar mass x moles

molar mass with density

mm = dRT/p

dalton's law

at constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the component gases

total pressure =

sum of partial pressures

mole fraction

individual moles/ total moles

pressure is

directly proportional to moles

Partial pressure =

mole fraction x total pressure

sum of mole fractions

= 1

vapour pressure of water

the partial pressure of water

What does vapour pressure depend on?

temperature of the water

what happens to vapour pressure as temp increases

vapour pressure increases

Why does vapor pressure increase with temperature?

h2o molecules have more energy to move from liquid to vapour --> more gas molecules = higher pressure

boiling point

the temperature at which the vapor pressure of a liquid is just equal to the external pressure on the liquid

average molar mass

(Xa)(MMa) + (Xb)(MMb)...

Gas Reaction Stoichiometry

stoichiometric coefficents relate number of moles of reactant and product

Kinetic Molecular Theory of Gases

a model used to explain the behavior of gases

Assumptions of Kinetic Molecular Theory

molecule size is negligible

molecules moving through space are considered point particles

collisions between molecules are elastic

no intermolecular forces

kinetic energy proportional to temp

more particles =

more collisions = more pressure

bigger container =

less collisions = lower pressure

greater mass =

greater pressure

mean squared speed

U^2 = 3RT/ MM

root mean square speed

Urms = sqrt(3RT/MM)

comparing root mean square speed

UA/UB = sqrt (MMB/MMA)

do lighter or heavier gases effuse

lighter

are lighter or heavier gases faster

lighter

rate of effusion

# moles gas escaped/ time

Graham's law of effusion

states that the rate of effusion for a gas is inversely proportional to the square root of its molar mass

graham's law formula

Rate A/Rate B = √molar mass B/molar mass A

enrichment factor formula

f lighter gas = sqrt (MMB/ MMA)

lighter gas has to be in denominator

Thermodynamics

The study of energy changes in physical and chemical processes`

energy measured in

Joules

energy

the capacity to do work

thermal energy symbol

q

Heat flows from

hot to cold

open system

matter and energy

closed system

energy but not matter

isolated system

no energy or matter

work

force x distance

pressure volume work

the work involved in the expansion or compression of gases

w= -P x ΔV

heat capacity

the number of heat units needed to raise the temperature of a body by one degree.

specific heat capacity

the energy required to raise the temperature of one gram of a substance by one degree

specific heat capacity formula

q=mc∆T

specific heat capacity units

J/kg°C or K

molar heat capacity

the energy required to raise the temperature of one mole of a substance by one degree

positive q

system gains heat

endothermic

negative q

system loses heat

exothermic

thermal equilibrium

The state of two or more objects or substances in thermal contact when they have reached a common temperature

-qlost=

Qgained

extensive property

a property that depends on the amount of matter in a sample

example of extensive property

volume, mass, energy

intensive property

a physical property that remains the same no matter how much of a substance is present

example if intensive properties

temp, density, mp, bp, hardness

are extensive properties additive

yes

are intensive properties additive

no

state function

A function that depends only on the initial and final states of a system, not on the path in between.

state function examples

density, internal energy, enthalpy, entropy

NOT work or heat

Are work and heat state functions?

no

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

total energy of isolated system is conserved

Internal energy

extensive property

state function

Ek+ Ep

what are the 2 ways to transfer energy

heat and work

exothermic

Releases heat

+q

endothermic

Absorbs heat

-q

work done to gas (compression)

positive work

work done by gas (expansion)

negative work

first law equation

ΔE = q + w

if system heated/ work done to it

+ΔE

if system cooled/does work

-ΔE

if system at constant volume what is E

ΔE = q

enthalpy

The heat content of a system at constant pressure

Enthalpy formula

H = E + PV

or at constant pressure : H= E=q

latent heat

heat absorbed or radiated during a change of phase at a constant temperature and pressure

solid to liquid

fusion

liquid to solid

-fusion

liquid to gas

vaporization

gas to liquid

-vaporization

solid to gas

sublimation

gas to solid

-sublimation

latent heat formula

ΔHn

Standard conditions

100kPa and 298K

-ΔH

exothermic

+ΔH

endothermic

Is enthalpy a state function?

Yes, enthalpy is a state function

Is enthalpy extensive or intensive?

extensive

calorimetry

The precise measurement of heat flow out of a system for chemical and physical processes

simple calorimetry formula

qrxn = -(qcal + qsol)

qcal=

Ccal∆T

what are the ways to measure qcal

1. place hot water in cal and measure Δt

2. perform rxn with known q and measure Δt

molar enthalpy

The enthalpy change associated with a physical, chemical or nuclear change involving one mole of a substance.