Defintions

Question 1

Relative atomic mass- Ar (words)

Answer 1

Is the average mass of an atom of an element on a scale where an atom of carbon 12 is exactly 12
= mass number in PT

Question 2

relative atomic mass (formula)

Answer 2

Mean mass of an atom / 1/12th mass of an atom of carbon 12

Question 3

Relative molecular mass

Answer 3

• average mass of a molecule on a scale where an atom of carbon 12 is 12

Question 4

Relative isotopic mass

Answer 4

• is the mass of an atom of an isotope of an element on a scale where an atom of carbon 12 is 12

Question 5

Atom economy

Answer 5

• is a theoretical value that measures the efficiency of an reaction
  AE= Mr of desired products / Mr of reactants

Question 6

Formula of ideal Gas equation

Answer 6

p x v = n x r x t
Pressure x volume = moles x gas constant x temperature

Question 7

Empirical formula

Answer 7

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

Question 8

Empirical formula

Answer 8

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

Question 9

Molecular formula

Answer 9

• actual no. Of atoms of each element in a compound

Question 10

Percentage yield

Answer 10

• experimental value of the efficiency of an reaction
  % yield = Actual yield / theoretical yield x 100%

Question 11

Ionisation

Answer 11

Is a process in which atoms lose electrons and become ions

Question 12

First ionisation energy

Answer 12

• is the enthalpy change for the removal of one mole of electrons of one mole of atom of an element in gas phase

Question 13

Define Hess’s law

Answer 13

• the enthalpy change in a reaction is independent of the route

Question 14

Define enthalpy of combustions

Answer 14

• the enthalpy change when 1 mol of a compound or substance is burned completely with all reactants and products in a standard state

Question 15

Define enthalpy of formation

Answer 15

• is the enthalpy change of 1 mol of compound or substance is formed from its elements with all reactants and prods in standard states

Question 16

Define mean bond enthalpy

Answer 16

• enthalpy needed to break 1 mol of covalent bonds averaged for that type of bond over different compounds

Question 17

Define enthalpy

Answer 17

• is the heat energy change at constant pressure

Question 18

Define electro negativity

Answer 18

• is the ability to attract a pair of electrons in the covalent bonds

Question 19

Define activation energy

Answer 19

• the minimum amount of energy needed to start an reaction

Question 20

Define rate of reaction

Answer 20

• a change in concentration per unit of time

Question 21

Define nucleophile

Answer 21

M1 an electron pair donor
E.g. hydroxide OH-, ammonia NH3, cyanide CN-

Question 22

Define substitution

Answer 22

• replacement of halogen by nucleophile

Question 23

Define hydrolysis

Answer 23

• breaking molecules using water

Question 24

Role of hydroxide ions in elimination

Answer 24

• act as a base / proton acceptor
• donates a pair of electrons to H atom

Question 25

Define elimination

Answer 25

- removal of a small molecule - often water - results in creating a double bond

Question 26

Define carbon neutral

Answer 26

- an activity which has no overall carbon emissions to the atmosphere

Question 27

Explain why value of mean bond enthalpy is less accurate than enthalpy of formation value ?(2)

Answer 27

- bond enthalpies are mean values - from a range of compounds

Question 28

Why is F2 a better oxidising agent than F - ? (3)

Answer 28

1) has high electronegativity = makes it wants electrons so will easily attract electrons towards themselves 2) small atomic size= strong nuclear attraction = easier to gain more electrons 3) F- already been reduced, it gained one electron already, it can’t accept more electrons = will be a reducing agent to be oxidised

Question 29

Why is I2 not a good reducing agent?

Answer 29

1) doesn’t have spare electrons to donate, it wants to gain electrons not lose = will be a good oxidising agent but F2 will be the best OA in all halogens

Question 30

Define molecular ion

Answer 30

Is an ion with its m/ z value equal to the Mr

Question 31

What is difference of electrospray and electron impact in mass spectrum of analysis ?

Answer 31

Electrospray use for looking at, identifying individual atoms Electron impact use for identifying compounds or molecules

Question 32

What is the use of high resolution mass spectrometry?

Answer 32

To distinguish compounds that have the same molecular mass Mr but different molecular formulas

Question 33

State why the precise relative atomic mass for 12 C isotope is exactly 12.00000?

Answer 33

By definition in their standard states

Question 34

How to find the Mr of an unknown using mass spectrum ?

Answer 34

Identify the highest m/z value ( not the highest peak)

Question 35

Give one reason why using water bath is better than direct heating with a bunsen burner with an alcohol (1)

Answer 35

Alcohol is flammable, using water bath reduce risk of exposure

Question 36

Ionic equation with known ppt examples e.g. BaSO4

Answer 36

Ba2+ + SO42- -> BaSO4

Question 37

Neutralisation ionic equation

Answer 37

H+ + OH- -> H2O

Question 38

Carbonate and hydrogen carbonate neutralisation

Answer 38

2H+ + CO32- -> H2O + CO2 H+ + HCO3- -> H2O + CO2

Question 39

Carbonate and hydrogen carbonate neutralisation

Answer 39

2H+ + CO32- -> H2O + CO2 H+ + HCO3- -> H2O + CO2