Topic 2

Question 1

what is atomic number

Answer 1

number of protons and neutrons in the nucleus of an atom

Question 2

what is mass number

Answer 2

total number of neutrons and protons in the nucleus of an atom

Question 3

what is relative abundance

Answer 3

the amount of one substance compared with another

Question 4

what is relative atomic mass

Answer 4

weighted mean mass of an atom compared with 1/12 of the mass of ana tom of Carbon-12

Question 5

what is relative isotopic mass

Answer 5

the mass of an atom of an isotope compared with 1/12 of the mass of an atom of Carbon-12

Question 6

what is relative formula mass

Answer 6

the mass of the formula unit of a compound with a giant structure

Question 7

what is relative molecular mass

Answer 7

mass of a simple molecule

Question 8

what is amount of substance

Answer 8

a quantity that uses mols as units

Question 9

what does anhydrous mean

Answer 9

crystalline compound containing no water

Question 10

what is Avogadro’s constant

Answer 10

number of atoms per mole of a substance
6.02 x 10^23

Question 11

what is empirical formula and how do you calculate it

Answer 11

simplest whole number ratio of atoms of each element in a compound
1. given mass
2. divide by molar mass of each element
3. divide by smallest number
4. may need to multiply until all are whole numbers

Question 12

what does hydrated mean

Answer 12

a crystalline that contains water

Question 13

what is ideal gas and its equation

Answer 13

a gas which has molecules that occupy negligible space with no interactions
between them

pV = nRT

Question 14

what is relative molecular formula

Answer 14

the average mass of one molecule of an element or compound compared to 1/12th the mass of an atom of carbon-12.

Question 15

what is the meaning of standard solution

Answer 15

a solution of known concentration

Question 16

rearrange pV = nRT to give the value of volume

Answer 16

v = nRT/P

Question 17

rearrange pV = nRT to give the value of pressure

Answer 17

p - nRT/V

Question 18

rearrange pV = nRT to give the value of moles

Answer 18

n = pV/RT

Question 19

rearrange pV = nRT to give the value of temperature

Answer 19

T = PV/nR

Question 20

what does each symbol in pV = nRT stand for

Answer 20

p = pressure (Pa/Pascals)
v = volume (m^3)
n = mols
R = ideal gas (8.314 J K-1 mol-1)
T = Temperature (K / Kelvin)

Question 21

what is atom economy

Answer 21

conversion efficiency of a chemical process in terms of all atoms involved and the desired products produced.

Question 22

what is the equation for atom economy

Answer 22

mr of desired product/ mr of all products/reactants

Question 23

what is % yield

Answer 23

the ratio between what is experimentally obtained and what is theoretically calculated, multiplied by 100%

Question 24

what is the equation for % yield

Answer 24

actual mass/theoretical mass x 100

Question 25

why will actual mass always be lower than theoretical mass

Answer 25

• some product is left in apparatus
• some product/reactant is lost to the surroundings
• incomplete reaction
• reactants are not pure

Question 26

Don’t answer

Answer 26

the atoms and bonds involved i the chemical reaction