Topic 1- Stoichiometric Relationships

Question 1

What is a physical change?

Answer 1

Change where no new substances are produced

Question 2

What is a chemical change?

Answer 2

A change that results in the formation of new chemical substances

Question 3

What is the law of conservation of mass?

Answer 3

Mass cannot be created or destroyed

Question 4

What is an element?

Answer 4

A substance that cannot be broken down into a simpler substance

Question 5

What is a compound?

Answer 5

Substance formed from two or more different elements chemically joined in a fixed ratio. Compounds have different properties from the elements they are made from

Question 6

What is a mixture?

Answer 6

Contains more than one element and/ or compound that are not chemically bonded so retain their individual properties

Question 7

Homogenous mixture

Answer 7

Has the same uniform appearance and composition throughout (salt solution)

Question 8

Heterogenous mixture

Answer 8

Consists of visibly different substances or phases (sand and water)

Question 9

Sublimation

Answer 9

Solid to gas

Question 10

Melting

Answer 10

Solid to liquid

Question 11

Evaporation/ boiling

Answer 11

Liquid to gas

Question 12

Freezing

Answer 12

Liquid to solid

Question 13

Condensation

Answer 13

Gas to liquid

Question 14

Deposition

Answer 14

Gas to solid

Question 15

What is a mole?

Answer 15

Unit of measurement used to measure the amount of a substance

Question 16

The number of particles in a mole is equal to the Avogadro constant which is:

Answer 16

6.02*10^23

Question 17

How many atoms are in a diatomic molecule?

Answer 17

2 (6.02E23)

Question 18

What are the diatomic molecules?

Answer 18

Br I N Cl H O F

Question 19

Ionic compounds do not form molecules, so in one mole of an ionic compound there are 6.02E23 ___________?

Answer 19

Formula units

Question 20

What is Absolute zero?

Answer 20

0 Kelvin; it is the temperature at which all movement of particles stops

Question 21

Atom economy

Answer 21

The level of efficiency of chemical reactions by comparing the molecular mass of atoms in the reactants with the molecular mass of atoms in reactants times 100 to get a percent. The higher the atom economy, the less the waste is produced and the more the efficient the reaction is

Question 22

Relative atomic mass

Answer 22

The relative atomic mass of an atom is a weighted average of the atomic masses of its isotopes and their relative abundances

Question 23

Relative molecular mass/ relative formula mass

Answer 23

For a molecule of formula unit, these are determined by combining the relative atomic mass values of the individual atoms or ions.

Question 24

Molar mass

Answer 24

The mass of one mole of a substance. It has the unit of grams per mole, (g mol^-1)

Question 25

Molecular formula vs empirical formula

Answer 25

Molecular is the actual number of atoms in a compound while the empirical formula is the lowest whole # ratio of atoms in a compound: ex: c4h10 is molecular
C2h5 is empirical