Chemistry Chapter 6

Question 1

Physical Change.

Answer 1

A change which does not alter the chemical composition of a substance.

-change, = chemical composition

Question 2

In general, which is easier to reverse: physical or chemical changes?

Answer 2

Physical changes are fairly easy to reverse, while chemical changes are much harder or impossible to reverse.

Question 3

What is the most common unit for measuring temperature change?

Answer 3

Celcius

Question 4

What are the two reference points used in the creation of the temperature scale?

Answer 4

Freezing = 0 C (32 F)
Boiling = 100 (212 F)

Question 5

How do you convert degrees Celsius to degrees Fahrenheit?

Answer 5

Degrees F = 9/5 (degrees C) + 32

Question 6

What type of change is phase change?

Answer 6

Physical

Question 7

What are the four phase changes and which 3 apply to chemistry mose?

Answer 7

Solid, liquid, gas + plasma

Question 8

Solid to liquid =

Answer 8

Melting

Question 9

Liquid to gas

Answer 9

Vaporizing

Question 10

Gas to liquid

Answer 10

Condensing

Question 11

Liquid to solid

Answer 11

Freezing

Question 12

Solid to gas

Answer 12

Sublimation

Question 13

Is volume additive?

Answer 13

Not necessarily because there is space between the molecules that make up any substance; mixing the two molecules squeezes some of that space.

Question 14

Is mass additive?

Answer 14

Yes.

Question 15

Kinetic Theory of Matter

Answer 15

The molecules (atoms) that make up a substance have space in between them, and they are in constant, random motion. The hotter the substance, the faster the motion.

Question 16

Explain the heating curve.

Answer 16

Temperature stays constant until a phase change is completed. E.g. ice is below 0 degrees, goes to 0 degrees when melting, when melting completed, temperature increase to 100 degrees. Stays at 100 degrees until evaporation completed. Water vapour can then be heated to higher temperature.

Question 17

How are the phases of water exceptional?

Answer 17

Kinetic phase — substance take up the least amount of volume in solid, then liquid and most volume in gas. Water is different — solid has a little bit more space between molecules than liquid at a similar temperature.

Question 18

Put the three major phases (solid, liquid, gas) in order of least volume to greatest volume according kinetic theory of matter for most substances.

Answer 18

Solid — liquid — gas

Question 19

Why is it important that water’s phases are exceptional to the kinetic theory of matter?

Answer 19

Otherwise ice would float on top of lakes and would not insulate lakes to allow aquatic life to survive the winter.

Question 20

What happens to atoms during chemical reactions?

Answer 20

They get rearranged and form new chemicals.

Question 21

What are the phase symbols used in chemical equations for the three most common phases?

Answer 21

Solid (a); liquid (l); gas (g)

Question 22

`In a chemical equation, what is on the left side of the arrow? The right?

Answer 22

Left = reactants; right = products

Question 23

What is a balanced chemical equation? How do you do this?

Answer 23

Number of reactant atoms is equal to number of product atoms. When balancing a chemical equation, you can change the numbers of the left of the molecules as much as you want. You just can’t change the subscripts in the chemical formulas. —> change number of molecules, not subscripts.

Question 24

What is a homonuclear diatomic? What are the seven examples?

Question 25

When is it not important to consider something homonuclear diatomic?

Answer 25

If it is not in a compound and not an ion.

Question 26

What do the numbers to the left of each formula tell you in a chemical reaction?

Answer 26

How many molecules (atoms) of that chemical participate in the reaction.

Question 27

What is a formation reaction?

Answer 27

A reaction in which two or more elements react together to form a a single compound.

Question 28

What is a decomposition reaction?

Answer 28

A reaction in which the only reactant is a compound and the products are the elements from which their compound is made.

Question 29

What is a single displacement reaction?

Answer 29

A reaction in which one element or ion in a compound is replaced by a different element or ion.

Question 30

What is a double displacement reaction?

Answer 30

A reaction in which two elements or ions in two different compounds switch places, each becoming part of the other compound.

Question 31

What is a combustion reaction?

Answer 31

The process by which a chemical reacts with oxygen to form on or more products as well as heat and usually light.

Question 32

What is complete combustion?

Answer 32

A combustion reaction in which the only products are carbon dioxide and water.

Question 33

What is incomplete combustion?

Answer 33

A combustion reaction in which carbon monoxide and /or elemental carbon are formed in addition to water.