Chapter 3 Keywords

Question 1

Amount of substance

Answer 1

Used to count the number of particles in a substance, measured in moles

Question 2

The mole

Answer 2

The unit for the amount of substance

Question 3

Avogardros number

Answer 3

The number of particles per mole of carbon 12 …6.02x1023 mol-1

Question 4

Empirical formula

Answer 4

Simplest whole number ratio of atoms of each element within a molecule of a compound

-important for substances that don’t exist as molecules eg C, NaCl that make giant crystalline stuctures of atoms or ions

Question 5

Molecular formula

Answer 5

The number and type of atoms of each element in a molecule

Question 6

Relative molecular mass

Answer 6

Mass of a molecule relative to the 1/12th the mass of an atom of C 12 (add up the RAM of things making up the molecule)

Eg for CO2 its 44

Question 7

Relative formula mass

Answer 7

Mass of a formula unit relative to 1/12th mass of an atom of carbon 12

Eg for NaCl its 58.5.. (add up the RAM of the empirical)

Question 8

Hydrated

Answer 8

Crystalline compound containing water of crystallisation

Question 9

Water of crystallisation

Answer 9

Water molecules bonded to the crystalline structure of a compound

Question 10

Anhydrous

Answer 10

Containing no waters of crystallisation

Question 11

Standard solution

Answer 11

Solution with a known concentration

Question 12

Molar gas volume

Answer 12

Volume per mole of gas molecules at a stated temperature and volume

Question 13

Theoretical yield

Answer 13

Maximum possible amount of product

Question 14

Limiting reagent

Answer 14

The reagent that is not in excess and that will be completely used up first. Compare the amount of moles. Calculations must be based on the limiting reagent.