Kinetic Energy & Chemical Particle – Chemistry Exam
The key terms of Chemistry Exam include, Chemical, Particle, Kinetic Energy, Liquid, Physical, Temperature, Molecular.
Explain how evaporation lowers the temperature of a liquid
When the molecules with the highest kinetic energy escape from the liquid, the average kinetic energy of the remaining particles is lower and the temperature decreases
In general, how are particles arranged in solids?
Particles in solids are packed tightly together in an orderly arrangement. The locations of the particles are fixed
What does the shape of a crystal tell you about the structure of a crystal?
The shape of a crystal reflects the arrangement of the particle within the solid
How do allotropes of an element differ?
Allotropes are different molecular forms of the same element in the same physical state
What phases are in equilibrium at a substance’s melting point?
solid and liquid
How do the melting points of ionic solids generally compare with those of molecular solids?Explain.
Ionic solids generally have, higher melting points than molecular solids
What is the difference between a crystal lattice and a unit cell?
a crystal lattice is a repeating array of unit cells
In a chemical reaction, how does the mass of the reactants compare with the mass of the products?
the mass of the products is always equal to the mass of the reactants
What is the main difference between physical changes and chemical changes?
Physical change, the chemical composition of a substance does not change
Classify the following changes as physical changes or chemical changes.
Water boils
salt dissolves in water
milk turns sour
metal rusts
physical
physical
chemical
chemical
According to the law of conservation of mass, when is mass conserved?
mass is conserved in every physical change of chemical reaction
Hydrogen and oxygen react chemically to form water. How much water would form if 4.8 grams of hydrogen reacted with 38.4 grams of oxygen?
4.8 g hydrogen+ 38.4 g oxygen=43.2 g water
Briefly describe the assumptions of kinetic theory as applied to gases.
a gas is composed of tiny particles whose motion is rapid, constant, and random; collisions between particles are perfectly elastic
Use kinetic theory to explain what causes gas pressure.
Gas pressure is the result of simultaneous collisions of billions of rapidly moving particle with an object
how is the Kelvin temperature of a substance related to the average kinetic energy of its particles ?
The kelvin temperature is directly proportional to the average Kinetic energy of the particles
Convert the following pressures to kPa
0.95atm
45 mm Hg
99kPa
6.078
By what factor does the average kinetic energy of the oxygen molecules in the cylinder decrease if a cylinder of oxygen gas is cooled from K(27 degrees Celsius) to 150 K (-124 degrees Celsius)
by one-half
What factors help determine the physical properties of liquids?
the interplay between the disruptive motions of particles in a liquid and the attractions among the particles
In terms of kinetic energy, explain how a molecule in a liquid evaporates.
a molecule with a certain minimum kinetic energy can escape from the surface of the liquid and vaporize
A liquid is in a closed container and has a constant vapor pressure. What is the relationship between the rate of evaporation of the liquid and the rate of condensation of the vapor in the container?
Rate of evaporation of the liquid equals the rate of condensation of the vapor
What conditions must exist for a liquid to boil?
particles throughout the liquid must have enough kinetic energy to vaporize
Use figure 13.9 to determine the boiling point of each liquid.
ethanoic acid at 27kPa
chloroform at 80 kPa
ethanol at 50 kPa
76 degree Celsius
52 degree Celsius
62 degree Celsius
Explain why the boiling point of a liquid varies with atmospheric pressure
Boiling occurs when the vapor pressure of a liquid equals the external pressure. If the atmospheric pressure changes, the boiling point will change
Explain how evaporation lowers the temperature of a liquid
When the molecules with the highest kinetic energy escape from the liquid, the average kinetic energy of the remaining particles is lower and the temperature decreases
In general, how are particles arranged in solids?
Particles in solids are packed tightly together in an orderly arrangement. The locations of the particles are fixed
What does the shape of a crystal tell you about the structure of a crystal?
The shape of a crystal reflects the arrangement of the particle within the solid
How do allotropes of an element differ?
Allotropes are different molecular forms of the same element in the same physical state
What phases are in equilibrium at a substance’s melting point?
solid and liquid
How do the melting points of ionic solids generally compare with those of molecular solids?Explain.
Ionic solids generally have, higher melting points than molecular solids
What is the difference between a crystal lattice and a unit cell?
a crystal lattice is a repeating array of unit cells