Ph 2 Amount of substance

Question 1

moles of a solid equation

Answer 1

mass / Mr

Question 2

moles of a solution equation

Answer 2

concentration x volume

Question 3

ideal gas equation

Answer 3

pressure x volume = moles x gas constant x temperature

Question 4

what is mass measured in for solid moles

Answer 4

grams

Question 5

unit of concentration

Answer 5

mol dm-3

g dm-3

Question 6

how to convert between units of concentration

Answer 6

multiply mol dm -3 by the Mr to get g dm-3

Question 7

what is volume measured in for solutions equation

Answer 7

dm3

Question 8

what are the units in the ideal gas equation

Answer 8

volume= m3
pressure = Pa
temperature = Kelvins

Question 9

1 ton in grams

Answer 9

1,000,000 grams

Question 10

1 kg in grams

Answer 10

1,000 grams

Question 11

1mg in grams

Answer 11

0.001 grams

Question 12

limiting reagent

Answer 12

the reactant that limits the amount of moles of product that can be made, the other product is in excess meaning there will be some left over after the reaction.

Question 13

m3 conversion =

Answer 13

cm3/1,000,000

dm3/1,000

Question 14

pressure conversion

Answer 14

Pa = KPa x 1000
Pa= MPa x 1,000,000

Question 15

temperature conversion

Answer 15

k=c + 273

Question 16

what is an ideal gas?

Answer 16

a gas with no forces between molecules, all particles size is negligible

Question 17

what can the ratio of the equation be used for

Answer 17

moles

volume of a gas

Question 18

final volume

Answer 18

volume of products + volume of excess left over

Question 19

what is atom economy?

Answer 19

a measure of the amount of starting materials that end up as useful products in theory

Question 20

equation for atom economy

Answer 20

(total Mr of desired product / total Mr of reactants ) x 100

Question 21

what is percentage yield?

Answer 21

Compares the mass of product you produce to the amount you expected. Practical based.

Question 22

equation to calculate percentage yield

Answer 22

( actual yield / theoretical yield ) x 100

Question 23

reasons why the actual yield may be lower than the theoretical yield

Answer 23

reversible reaction
reaction did not reach completion
other reactions occurred
product lost during isolation

Question 24

what is relative molecular mass

Answer 24

the average mass of one molecule relative to 1/12 the mass of one atom of carbon twelve

Question 25

what is the empirical formula

Answer 25

the simplest ratio of atoms of each element in a compound

Question 26

what is the molecular formula

Answer 26

the actual ratio of atoms of each element in a compound

Question 27

steps to find the empirical formula

Answer 27

1) write out the mass of percentage of that element in the compound
2) Divide by the Ar of the element
3) Divide by the smallest to get a to one ratio
4) Make ratio to whole numbers

Question 28

how to find the molecular formula from the empirical formula

Answer 28

1) Find the Mr of the compound
2) divide the Mr of the compound by the Mr of the empirical formula
3) Multiply the empirical formula values by this amount.

Question 29

how to find the mass of an element in a compound of known mass

Answer 29

mass of compound x (Ar of element/Mr of compound)