CHe2mistry Proficiency Review

Pre-review Questions1. A student ran tests on a mystery substance and found that is

has a definite volume, high density, and flows easily. Which state of matter is it and why?

a) It is a solid because it has a definite volume and high density.b) It is a liquid because it has a definite volume and high density.c) It is a gas because it has a definite volume and flows easily.d) It is a liquid because it has a definite volume and flows easily.

2. Which of the following correctly describes the motion of particles in a solid?

a) They do not move at all.b) They move rapidly around in random patterns.c) They vibrate in a set pattern.d) They flow easily, but slowly around each other.

3. Analyze the table below. The following symbols each represent one atom of different elements:

Which of the above correctly represents a chemical equation showing the law of conservation of mass in a chemical reaction?

a) I b) II c) III d) IV

4. What happens when wood burns with the oxygen in air to form water and carbon dioxide?a) The mass of the products becomes less than the mass of the

reactants.b) Most of the mass of the wood is converted into energy.c) More energy is absorbed than given off in the reaction.d) The mass of the wood and oxygen reacted equals the mass of

the products.

5. When photosynthesis occurs, carbon dioxide and water produce glucose and oxygen. The balanced equation is 6 CO2 + 6 H2O C6H12O6 + 6 O2. How many molecules of C6H12O6 are produced when 18 molecules O2 are produced?a) 1 molecule C6H12O6 b) 2 molecules C6H12O6 c) 3 molecules C6H12O6 d) 6 molecules C6H12O6

Kinetic Molecular TheoryExplains the forces between molecules and the energy that they possess

• Matter is composed of small particles (molecules, ions, atoms).

• The energy and organization of these particles determines the physical state and properties of matter.

• All particles are in constant, random motion and possess kinetic energy.

• The amount of kinetic energy is directly related to temperature. Kinetic energy is transferred from one particle to another through collisions.

There are three different, common physical states of matter.

Solids

• Strong intermolecular attractions hold individual particles close together

• Particles vibrate • Defined volumes and shapes and do not

flow • High densities

Liquids• Particles are randomly packed and close to each

other• Intermolecular attractions between particles is

not as strong as in solids• Particles slide over each other but do not

completely separate • Definite volume but an indefinite shape (take the shape of their containers)• Flow.

Gases• Intermolecular attractions between

particles is very small • Particles move far apart from each other• Particles are in constant, random

motion, independent of each other• No specific shape or volume ( take the

shape of their containers )• Low densities • Flow

SOLID LIQUID GAS

ParticleArrangement

Fixed Random Random

Closeness of Particles

Close Close Far Apart

Attraction between Particles

Strong Moderate Little to none

Motion of Particles

Held close by their

attractions of charge

Slide over each other

Move constantly and

randomly, independent

Volume Definite

volumeDefinite volume

Takes the volume of its

container

Shape Definite shape

Takes the shape of its container

Takes the shape of its container

Flow Does not Easily EasilyDensity

High

High (lower than the

corresponding solid)

Low

Activity:

• Use the information squares in the

plastic baggie provided to complete

the chart on solids, liquids, and

gases. Check your answers with the

teacher when you are done.

To Teacher

• Pass Out Materials• Continue presentation with the solution to the

table when the majority of students are done.

SOLID LIQUID GAS

ParticleArrangement

Fixed Random Random

Closeness of Particles

Close Close Far Apart

Attraction between Particles Strong Moderate Little to none

Motion of ParticlesHeld close by their

attractions of charge

Slide over each other

Move constantly and randomly, independent

Volume Definite volume Definite volume Takes the volume of

its container

Shape Definite shape Takes the shape of its container

Takes the shape of its container

Flow Does not Easily EasilyDensity

High High (lower than the

corresponding solid)

Low

More Chemistry Review• All matter is composed of atoms.• Each element is made of a different kind of

atom. • Atoms of different elements have different

masses. • Atoms are neither created nor destroyed in

chemical reactions. (Law of Conservation of Mass)

• Atoms of different elements combine in fixed number ratios. Example: H20, H2SO4

• More than one ratio possible for a given combination of elements.

Study the EquationC + O2 CO2

(Reactants) (Products)

• Ratio of C to O atoms to form CO2

is 1 C atom to 2 O atoms (1:2) • This equation is balanced. Why???• There is one atom of Carbon and two atoms of Oxygen on both sides of the

equation.

• Atoms have been rearranged in their bonds

• Number of atoms in reactants equal the atoms in the product

Study the EquationCH4 + O2 CO2 + H2O

• Is this equation balanced?• No. The number of atoms of Hydrogen and Oxygen are not the same

on each side of the equation.

• What can you do to make the equation balanced?• Add the number 2 before the O2 and H2O molecules

CH4 + 2 O2 CO2 + 2 H2O

Study the Equation Subscripts

CH4 + 2 O2 CO2 + 2 H2O Coefficients

What is the coefficient before the CH4 ? (1)

What is the coefficient of O2 ? (2)

What is the subscript of C ? (1) What is the subscript for H in the products ? (2)

How many atoms of hydrogen are there in the product? (4)

How many molecules of CO2 ? (1)

To balance equations….

• Coefficients in front of each chemical formula must be changed. • No atoms of any element are

created nor destroyed.

• Bonds are broken and reformed.

In the reaction below, the molecular ratio is 1 CH4 to 2 O2 to 1 CO2 to 2 H2O

ION (SPECIAL ATOMS)

a. Atom that gains or loses electrons

b. Have an unequal number of e- and p+

c. Have net negative or positive charge

d. Very reactive atomse. Elements on the periodic table

are neutral. This means they have the same number of protons and electrons. However, they will always fill there valence shell for stability.

Ion

Formation of Compounds by BondingA. Compounds = 2 or more elements in a fixed

ratioB. Have new properties from atoms

C. Covalent Bonds = 2 atoms share one or more valence electrons (forms molecules); very strong bond

D. Ionic Bonds = transfer of electrons; formed by electrical attraction between two oppositely charged ions.

(forms crystals)

Review Equations

• Look in your packet and review the equations for photosynthesis and cellular respiration.

• How do they compare to each other?• What are the products for each?• What are the reactants?

Post-review Questions1. A student ran tests on a mystery substance and found

that is has a definite volume, high density, and flows easily. Which state of matter is it and why?

a) It is a solid because it has a definite volume and high density.

b) It is a liquid because it has a definite volume and high density.

c) It is a gas because it has a definite volume and flows easily.

d) It is a liquid because it has a definite volume and flows easily.

1. A student ran tests on a mystery substance and found that is has a definite volume, high density, and flows easily. Which state of matter is it and why?

a) It is a solid because it has a definite volume and high density.

b) It is a liquid because it has a definite volume and high density.

c) It is a gas because it has a definite volume and flows easily.

d) It is a liquid because it has a definite volume and flows easily.

2. Which of the following correctly describes the motion of particles in a solid?

a) They do not move at all.b) They move rapidly around in random patterns.c) They vibrate in a set pattern.d) They flow easily, but slowly around each other.

2. Which of the following correctly describes the motion of particles in a solid?

a) They do not move at all.b) They move rapidly around in random patterns.c) They vibrate in a set pattern.d) They flow easily, but slowly around each other.

3. Analyze the table below. The following symbols each represent one atom of different elements:

Which of the above correctly represents a chemical equation showing the law of conservation of mass in a chemical reaction?

a) I b) II c) III d) IV

3. Analyze the table below. The following symbols each represent one atom of different elements:

Which of the above correctly represents a chemical equation showing the law of conservation of mass in a chemical reaction?

a) I b) II c) III d) IV

4. What happens when wood burns with the oxygen in air to form water and carbon dioxide?a) The mass of the products becomes less than the mass of the

reactants.b) Most of the mass of the wood is converted into energy.c) More energy is absorbed than given off in the reaction.d) The mass of the wood and oxygen reacted equals the mass of

the products.

4. What happens when wood burns with the oxygen in air to form water and carbon dioxide?a) The mass of the products becomes less than the mass of the

reactants.b) Most of the mass of the wood is converted into energy.c) More energy is absorbed than given off in the reaction.d) The mass of the wood and oxygen reacted equals the mass of

the products.

5. When photosynthesis occurs, carbon dioxide and water produce glucose and oxygen. The balanced equation is 6 CO2 + 6 H2O C6H12O6 + 6 O2. How many molecules of C6H12O6 are produced when 18 molecules O2 are produced?a) 1 molecule C6H12O6 b) 2 molecules C6H12O6 c) 3 molecules C6H12O6 d) 6 molecules C6H12O6

5. When photosynthesis occurs, carbon dioxide and water produce glucose and oxygen. The balanced equation is 6 CO2 + 6 H2O C6H12O6 + 6 O2. How many molecules of C6H12O6 are produced when 18 molecules O2 are produced?a) 1 molecule C6H12O6 b) 2 molecules C6H12O6 c) 3 molecules C6H12O6 d) 6 molecules C6H12O6