amount of substances

Question 1

a-1 moles contains

Answer 1

-6.02 x 10 ^23 atoms/molecules

Question 2

-how do we calculate the number of particles

Answer 2

-Avogadros number X Number of moles

Question 3

-how do we calculate moles

Answer 3

-moles= mass/mr

Question 4

-how do we calculate the number of moles in a solution

Answer 4

-moles= concentration(moldm-3) X volume (dm3)

Question 5

-ideal gas equation: number of moles in a specific volume of gas

Answer 5

-pV=nRT

Question 6

-p=

Answer 6

-pressure( Pa)

Question 7

-V=

Answer 7

-volume ( m3)

Question 8

-n

Answer 8

-number of moles

Question 9

-R=

Answer 9

-Gas constant (8.31 JK-1 mole-1 ) given in exam

Question 10

-T

Answer 10

-temperature ( K)

Question 11

-converting units

Answer 11

m—x-10 —-dm—-x10——cm

m2——x100——dm2——x100—–cm2

m3——x1000——dm3—–x1000—–cm3

Question 12

-1Kpa=

Answer 12

-1000P

Question 13

working out theoretical mass:
E.g: How much CaO can be made when 34g of Ca is burnt completely in oxygen

2CaO+ O2—>2CaO

Answer 13

1) write out equation and balance it

2) work out the Mr/ Ar of species involved. write these as masses in g

3) divide the Ca side by 80 to find 1g then multiply by 34 to get 34g. Do the same for CaO side

Question 14

-relative atomic mass (Ar)

Answer 14

-the average mass of one atom compared to one twelfth of the mass of one atom of carbon-12

Question 15

-relative molecular mass (Mr)

Answer 15

-the average mass of a molecule compared to one twelfth of the mass of an atom of carbon-12.

Question 16

-degree celsius to K

Answer 16

+ 273

Question 17

-empirical formula:

Answer 17

1) find the mass of each of the element present in a compound

2) work out the number of moles of atoms of each element
- number of moles= mass of / mass of 1 mol of an element

3) convert the number of moles of each element into a whole number ratio

Question 18

-state what is meant by empirical formula

Answer 18

-simplest whole number ratio of atoms of each element in a compound

Question 19

state what is meant by molecular formula

Answer 19

actual number of atoms of each element in the compound

Question 20

1000mg=
1000g=
1000kg=

Answer 20

1g
1kg
1tonne

Question 21

-what is the formula of sulfate

Answer 21

SO4 2-

Question 22

-formula of hydroxide

Answer 22

OH-

Question 23

-formula for carbonate

Answer 23

CO3 2-

Question 24

-formula for ammonium

Answer 24

NH4 +

Question 25

calculating purity

Answer 25

mass of solute/ total mass of the substance

• X 100

Question 26

calculating % atom economy

Answer 26

molecular mass of desired product/ sum of molecular masses of all reactants

X100

Question 27

calculating % yield

Answer 27

yield/maximum theoretical yield

X100