2.1.3 Amounts of Substance

Question 1

avogadros number (NA)

Answer 1

6.02 x 10 (23)

Question 2

define mole

Answer 2

the amount of substance with contains as many elementary particles as there are atoms in exactly 12g of carbon-12

Question 3

how do you covert moles into the number of particles in a substance

Answer 3

moles = number of particles / 6.02 x 10 (23)

Question 4

define molar mass

Answer 4

the mass of one mole of substance. its units are (gmol-1)

Question 5

how do you calculate the percentage by mass of an element in a compound?

Answer 5

% by mass = (mass number x mass of element) x100

relative molecular mass

Question 6

what is relative formula mass/ molecular mass

Answer 6

the relative atomic mass of an element in a compound x the mass of the element in the compound

Question 7

what is the empirical formula

Answer 7

the simplest whole number ratio of atoms of each element present in a compound

Question 8

what is the molecular formula

Answer 8

the actual number of atoms of each element in a molecule

Question 9

what are the units of molar mass

Answer 9

gmol-1

Question 10

equation for finding the amount of moles in a substance

Answer 10

moles = mass / Ar, Mr, RFM

Question 11

how do you calculate the mass of a substance using the moles

Answer 11

mass = moles x Ar, Mr, RFM

Question 12

how do you convert the number of particles into moles

Answer 12

number or particles = moles x 6.02 x10(23)

Question 13

what’s the equation for finding the multiple to work out molecular formula from empirical formula

Answer 13

multiple = molar mass / EFM

Question 14

equation for moles of a gas

Answer 14

n(gas) = v(dm3) / 24

n(gas) = v(cm3) / 24,000

Question 15

equation for volume of gas

Answer 15

v(dm3) = n x 24

v(cm3) = n x 24,000

Question 16

ideal gas equation

Answer 16

Pv = nRT

Question 17

how to convert degrees c to kelvin

Answer 17

+273

Question 18

how do convert kpa to pa

Answer 18

x1000

Question 19

how to convert dm3 to m3

Answer 19

divide by 1000

Question 20

how to convert cm3 to m3

Answer 20

divide by 1,000,000

Question 21

how to find moles in a solution

Answer 21

n= c v(cm3) / 1000

n= c / v

Question 22

how to find concentration of a solution

Answer 22

c= n x 1000 / v(cm3)

c= n x 1000

Question 23

how to find volume of a solution

Answer 23

v(cm3)= n x 1000 / c

v(dm3)= n / c

Question 24

how to convert moldm-3 to gdm-3

Answer 24

moldm-3 x Mr

Question 25

how to convert gdm-3 to moldm-3

Answer 25

moldm-3 = gdm-3 / Mr

Question 26

%uncertainty

Answer 26

= (number of readings x equiptment uncertainty) / quantity measured x100

Question 27

%yield

Answer 27

= actual yield / theoretical yield x100

Question 28

%atom economy

Answer 28

=mr of desired product / mr of all product x100

Question 29

empirical formula definition

Answer 29

the simplest whole number ratio of the number of atoms of elements in a compound

Question 30

how many readings are taken for a burette test

Answer 30

2