Topic 2: Amount of substance

Question 1

Avogadros number

Answer 1

6.022x10^23

Question 2

Concentration equ’n

Answer 2

Moles/volume

Question 3

Moles equ’n

Answer 3

Mass/Mr (n=m/mr)

Question 4

Mr/Ar in grams

Answer 4

1 mole of an atom/ molecule is its Ar/Mr in grams

Question 5

Ideal Gas Equation

Answer 5

PV=nRT

Question 6

P unit in gas equation

Answer 6

Pressure (Pa)

Question 7

V unit in gas equation

Answer 7

Volume (m^3)

Question 8

R unit in gas equation

Answer 8

Gas constant (8.31)(JK^-1mol^-1)

Question 9

T unit in gas equation

Answer 9

Temp. (K)

Question 10

Empirical Formula

Answer 10

Simplest whole number ratio of atoms of each element in a compound.

Question 11

Molecular Formula

Answer 11

The actual number of atoms of each element in a compound.

Question 12

hydrating molecular and empirical formula questions

Question 13

Ammonium

Answer 13

NH4^+

Question 14

Nitrate

Answer 14

NO3^-

Question 15

Sulfate

Answer 15

SO4^-2

Question 16

Carbonate

Answer 16

CO3^-2

Question 17

Phosphate

Answer 17

PO4^-3

Question 18

Hydroxide

Answer 18

OH^-

Question 19

Ionic Equation def

Answer 19

Chemical equations that show only ions that participate in a chemical reaction

Question 20

Ionic Equation Steps

Answer 20

• All solids, liquid and gases stay
• Ionic aqueous substances split into ions
• Eliminate spectator ions (those that don’t change state or position)
• Write ionic equation - only include ions that change include state symbols and charges
• Check charges

Question 21

Percentage Yield

Answer 21

Actual yield (mass/moles) /theoretical yield (mass/moles) x 100%

Question 22

Atom Economy

Answer 22

mass of desired product/ total mass of reactants x 100%

Question 23

Water of Crystallisation

Answer 23

Water of crystallisation is water which is locked into a crystal in a fixed way. Heat until a constant mass. e.g. Copper(II) sulfate has the formula CuSO4·5H2O.

Question 24

Titration Concordent Results

Answer 24

Within 0.10cm^3 of each other

Question 25

Acid turns phenolphthalein

Answer 25

Colourless

Question 26

Alkali turns phenolphthalein

Answer 26

Pink

Question 27

Uncertainty

Answer 27

The estimated error when taking a measurement.

Question 28

Uncertainty in titration

Answer 28

half a division +_0.05cm^3 half a division +_0.05cm^3 volume of a drop +_0.05cm^3 total uncertainty +_0.15cm^3

Question 29

Uncertainty of a reading

Answer 29

Plus or minus half of the smallest division.

Question 30

Percentage Uncertainty

Answer 30

uncertainty/ mean result x100%

Question 31

Percentage Uncertainty of titration

Answer 31

Total uncertainty (+_0.15cm^3)/ Mean titre x100%

Question 32

Back titration

Answer 32

dont forget they exist - remember they take brain power