Solids and Gas Laws Test

Amorphous Solid

no ordering of particles (no real shape)

Crystalline Solid

extensive and regular ordering of particles into a 3D structure

Crystal Lattice Structure

has repeating unit cells

5 Types of Crystalline Solids

• atomic

• molecular

• ionic

• metallic

• covalent network

Atomic

individual atoms (noble gases)

Molecular

has LDF, dipole-dipole, hydrogen bonding (ice)

Ionic

ionic bonding

• hard and high melting points (b/c of strength bonds)

• brittle

• table salt (NaCl)

Metallic

metallic bonding

• malleable (bendable)

• ductile (can make it into strings)

Covalent Network

strongest and very large

• diamonds, graphite, SiO2

• nonconductors

• high melting and boiling points

Gas Constant

R (0.08216 Latm/Kmol)

STP

273K and 1atm

Ideal Gas Law

PV=nRT

Partial Pressure

Pa= (Ptotal) x (Xa (mole fraction/total moles))

KE

½(mv²)

Density equation

D= m/v

Kelvin

C + 273

Kinetic Molecular Theory (KMT)

talks about properties of gases and makes 5 assumptions

helps explain observable properties of solids, gases, and liquids

what are the 5 assumptions of the KMT

1. gases are composed of very small particles (atoms and molecules)

2. the size of the molecules is much smaller compared to the distance between them: the volume of the gas particles is negligible

3. gas particles are in constant motion

   • colliding with each other and the walls of the container

   • the collisions with the walls causes the pressure of gas

4. Gas particles neither attract nor repel each other

   • collisions are elastic= no KE lost; KE transferred

5. the average kinetic energy of the gas is proportional to the Kelvin Temperature

What makes a gas an ideal gas

if it obeys all 5 postulates of the KMT

Is it possible to be an ideal gas?

No, but gases can approach ideal behavior

• Non-polar gases, low pressure, high temperature

Boyle’s Law

P1V1=P2V2

• pressure and volume are inversely proportional

• if we decrease the size of the container then the collisions with the wall are increasing (pressure increases)

Charles’s Law

V1/T1=V2/T2

• pressure is constant

• if a sample of a gas is heated then the volume has to increase

• V and T are directly proportional

Gay Lussac’s Law

P1/T1=P2/T2

• the volume is constant and the amount is constant

• is temperature increases then gas particles have higher KE so they hit more→ high pressure

Combined Gas Law

(P1V1)/T1=(P2V2)/T2

• the amount is constant= no gas can get in or out

• temperature needs to be in Kelvin

Avogadro’s Law

V1/n1=V2/n2

• constant temperature and pressure

• volume has to increase to keep pressure constant

• direct relationship between volume and the number of moles

• Ideal Gas Law at STP= 22.4 L/mol

  • make sure gas is at STP

What is the relationship between rates of effusion and molecular mass

inverse relationship

• the lower the molecular mass the faster the gas effuses (effusion is the gas leaving the container)

Non-Ideal Gases

• larger and more concentrated, and strong intermolecular forces of the gas, the more it deviates from the ideal has equations

• Van Der Waals equation

  • we see more deviations at high pressure and low temperature

Collect Gas Over Water

total pressure collected= (p of H2O) + (p of gas)

• p of gas= (total pressure) - (p of H2O)

• P of H2O given to you for the specific temperature

Solvent

dissolving medium (H2O)

Solute

substance dissolved in solvent

Saturated

has the maximum amount of solute dissolved at a given temperature

Unsaturated

has less than maximum amount of solute dissolved

Supersaturated

dissolve more than the maximum solute

• very unstable (Ex: rock candy)

• excess solute will separate eventually (very unstable)