Less volatile than means it has a higher boiling point than.
Terminology
- Matter
- Anything that has mass and takes up space.
- Models
- Help explain differentiating characteristics of substances.
Particulate Model of Matter
_PMM
- Assumes that macroscopic properties differ from individual particle properties.
- Macroscopic properties are dependant on microscopic particle properties
- Assumption 1
- Any macroscopic substance is made up of a large quantity of microscopic particles.
- Assumption 2
- Particles of matter are constantly moving randomly through space.
-
- When particles hit a wall they exert pressure (P) per force area.
-
- Pressure depends on the: number of particles, volume, size of particles, speed of particles.
- Assumption 3
- Particles interact with each other depending on the distance between them.
-
- Result of intermolecular forces.
-
- Particles attract to each other until they get too close and then they repulse.
SI Units
1 m^3 = 1,000 L
Cubic meters are used to measure volumes of solids. Liters are used to measure volumes of liquids.
- Density
- mass/volume
- g/cm^3
- g/mL
- Mass
- The amount of matter,
- Not the same as weight.
- Weight
- The force of gravity on the object.
- Not the same as mass.
- Precision
- How well replicate measures agree with each other.
- Accuracy
- How close a measure is to the true value.
Phase Changes
Phase changes are physical changes! Temp stays constant during phase changes!
- As the phase changes, potential energy increases, but kinetic energy stays the same.
- An increase of energy breaks apart attractive intermolecular forces.
- Kinetic Energy
- Energy in motion (sa. affected by temperature)
- Potential Energy
- Energy stored in bonds.
Modeling Gasses
- Homogenous mixtures
- can compress/expand
- Low densities
- Can mix via diffusion.
- Collisions do occur.
Kinetic Molecular Theory of Gasses
- Assumption 1
- Particles are always in motion and only change direction after collisions.
- Assumption 2
- Most of volume is empty space
- Assumption 3
- Pressure in a container results from collisions with gas molecules and the wall of the container.
- Assumption 4
- Gas molecules themselves don't experience attractive or repulsive forces
-
- Collisions do not result in the loss of energy!
- Assumption 5
- Average kinetic energy of gas is directly proportional to temp of the gas in K.
-
- Goes both ways.
1 atm = 760 mmHg
Strongest intermolecular forces = hardest to boil. Requires more energy.
Distribution Plot
- Modeling Average Kinetic Energy
- Not all particles in a substance move at the same speed!
- Temperature is a measure of energy.
- X-axis shows particle velocity.
- Y-axis shoes fraction of particles.
- Top of the bell shoes average velocity.
Kinetic Energy
- Kinetic Energy
- KE = 1/2 m * v^2
- Measured in Joules
- 1 J = 1 (kg * m^2) / s^2
- If we double the mass of a particle, then the kinetic energy also doubles.
- Temp and energy are directly proportional.
- Heavier things move slower.