Chemistry - Gas Laws, Thermodynamics

Volume, Pressure, Temperature

Litres - L (si unit) dm^3 - decimeter cubed (convenient and used used in IB)

C - degrees celsius K - kelvin

K = C + 273.15

0 K: absolute zero

The force applied over an area (m^2)

N/m^2 Pa - pascal

1.0 atm = 101325 Pa = 101.325 kPa = 1.01325 bar = 760 torr = 760 mmHg = 14.6959 psi

Mercury

"Standard" set of conditions exactly 273 kPa and 100. kPa

exactly 298 K and 100 kPa

• As pressure increases, volume decreases

• As temperature increases, volume increases

• As temperature decreases, pressure decreases

• As temperature increases, pressure increases

P ∝ 1/V PV = constant

T ∝ V T/V = constant

P ∝ T P/T = constant

P1V1=P2V2 @ Constant T

V1/T1 = V2/T2 @ Constant P

P1/T1 = P2/T2 @ Constant V

P1V1/T1=P2V2/T2 @ constant mols

T - always use Kelvin P, V - units do not matter as long as the units are the same on both sides

As you add additional gas to a system, the volume of that gas will increase

• temperature and pressure are held constant

n ∝ V V1/n1 = V2/n2

I) The volume of gas particles themselves are negligable compared to the volume of the gas II) There are no attractive forces between the gas particles

PV = nRT

Ideal gas constant (in units J/k * mol) Volume in Ideal Gas Law formula must be in m^3, pressure in Pa, and temperature in K

The study of how heat works energy + temperature relate to each other

• energy cannot be created or destroyed

• you can only transfer energy

A form of energy Thermal energy

the energy of motion Kinetic Energy - 1/2m(^2)

mass

velocity

a measure of the average kinetic energy

• energy is added to substance -> internal energy goes up -> particles have more kinetic energy -> particles move faster -> higher temperature

energy that is stored in a system

total internal energy of a system

• stored in the bonds

change in Enthalpy

ΔH = Hproducts - Hreactants

• total internal energy goes up (increases)

• absorbs heat

• ΔH is positive

• total internal energy does down (decreases)

• releases heat

• ΔH is negative

the science or act of measuring changes in state variables of a body for the purpose of deriving the heat transfer associated with changes of its state due, for example, to chemical reactions, physical changes, or phase transitions under specified constraints (google)

q = CpmΔT

Heat energy (J - energy measured in joules)

Heat capacity (J/g*K)

Change in temperature (K, C)

change in enthalpy

The energy needed to break 1 mole of a bond of a gaseous molecule averaged over similar compounds

The products are more stable than the reactants, as they have a lower energy level, making it easier to maintain

The enthalpy change for a reaction that is carried out in a series of steps is equal to the sum of the enthalpy changes for the individual steps