Kinetic Theory
What state of matter contains particles moving the fastest?
Gas
Given 4H2O,
What does the number 4 above represent?
What does the number 2 above represent?
4 molecules of water (4 H2O's)
2 hydrogens in each molecule of water.
Which property describes how much mass is in a given volume of space?
Density (calculated by dividing: mass/volume)
Energy that moves through space or matter without transferring matter is called what?
Waves
Attractive force that acts between all objects that have mass. What does this force depend on?
Gravity; depends on mass and distance
According to kinetic theory, what happens to particle motion when temperature increases?
Particles move faster (kinetic energy increases)
A molecule contains two hydrogen atoms and one oxygen atom. Write the chemical formula for this molecule and what compound is this?
Water (chemical formula: H2O)
Is melting point a physical property or a chemical property? Why do different molecules melt at different temperatures?
What is the amplitude of a wave?
The distance from the resting position to the crest or trough. Half the height of the wave.
What happens to an object if no unbalanced forces act on it?
The object continues in motion at a constant velocity (does not accelerate or decelerate) or stays at rest.
A syringe full of gas is compressed. What happens to the distance between particles?
The distance between particles decreases.
When hydrogen combines with oxygen to form water, what type of change occurs?
Chemical reaction (oxygen and hydrogen are rearranging to form water)
2H2 + O2 --> 2H2O
An unknown substance has a density of 2.7 g/cm3 and a melting point of 660ยบC. Why is knowing the density and melting point of an unknown substance useful?
The density and melting point can be compared to known values of known substances to identify the unknown substance.
If the frequency of a wave increases, what happens to the wavelength and the energy of the wave.
Pitch would also increase (higher pitched)
Color would shift to be more blue (higher energy)
If the mass of an object increases but the force stays the same, what happens to the acceleration (hint: F=ma)
Acceleration must decrease.
(eg. mass = 1, acceleration = 4, Force = 4 --> now test increasing mass, m=2, acceleration = ?, force = 4, acceleration = 2)
Acceleration went from 4 --> 2 (decreased)
Why can gases be easily compressed, but solids cannot?
Gas particles have large spaces between them, while solid particles are tightly packed in a rigid structure.
In the reaction 2H2 + O2 --> 2H2O, how many atoms of H are in the reactants? How many atoms of H are in the products? Which principle does this showcase?
4 atoms in each the reactants and products. This showcases the law of conservation of matter.
Two substances look the same but have different melting points. What does this tell us?
The substances are different (example: baking soda and sugar)
When a wave hits a surface and bounces of at the same angle, what is this called?
Reflection
What is Newton's 3rd Law? What two forces are acting on a ball sitting on the floor not moving? Are these forces balanced or unbalanced?
A sealed container of gas is heated. What happens to particle motion and pressure.
Particles move faster and collide with the container more often, increasing the pressure.
During a chemical reaction, atoms are rearranged but not created nor destroyed. Which law of nature describes this idea and when does it apply?
Law of Conservation of Mass; always applies
Why can properties like boiling point and density be used to identify unknown substances?
They are unique to each substance and there is a database that has all of the known values to compare unknowns to.
What are the 3 types of heat transfer? Note whether each type requires contact or not and whether each type requires a medium or not.
Conduction - heat travels to cooler areas by direct contact; requires contact, requires medium
Convection - hot fluids rise, cool fluids fall creating cycles/currents; no contact required; fluid medium required (liquid or gas)
Radiation - energy travels as a wave without contact; no contact required, no medium required = can work in a vacuum/empty space)
A rocket pushes gas downward to move upward. Which Newton's law explains this?
Newton's 3rd Law (action-reaction; force pairs)