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Question 1

How does mass spectrometry work

Answer 1

• sample in vaporised form is inputted into a vacuum chamber
• into an isonisation area
• using an electron gun: accelerates electrons to become positive ions
• ions are accelerated
• detected where lighter first and then heavier

Question 2

Nitrite

Answer 2

NO2 -

Question 3

Sulphite

Answer 3

SO3 -2

Question 4

Hydrogen carbonate

Answer 4

HCO3 -

Question 5

Dichromate

Answer 5

Cr2O7 -2

Question 6

Manganate (7)

Answer 6

MnO4 -

Question 7

Nitrates and chlorides

Answer 7

Are always soluble

Question 8

All carbonates are

Answer 8

Insoluble except for group 1 and ammonium

Question 9

Mole definition

Answer 9

Amount of substance found in 12g of C-12, as one mole of substance contains the same number of entities as there are in 12g of C-12

Question 10

How would you reduce percentage uncertainty in mass of residue

Answer 10

• use a mass balance to more dp
• use a larger mass of the product

Question 11

How can you tell all water removed

Answer 11

Heat mass and record until constant/ unchanged mass to indicate all water has been removed

Question 12

Ideal gas changing from m3 to cm 3 and dm3

Answer 12

• 10^6 and *10^3

Question 13

In acid base eq, when given mol for certain vol…

Answer 13

Multiply mol by sf that volume has increased by and use

Question 14

Uncertainty

Answer 14

Uncertainty of equipment/ measurement *100
If used twice like burette, *2

Question 15

Relative formula mass

Answer 15

Mass of a formula unit relative to 1/12th the mass of a c-12

Question 16

Assumption for water of crystallisation

Answer 16

• all water has been lost
• no further decomposition as we cannot tell without a colour change

Question 17

How to tell if incomplete combustion

Answer 17

• see if moles made are more or less than the ‘limiting reactant’ that is given

Question 18

How do isotopes take part in chemical reactions

Answer 18

As chemical reactions are only dependant on number of electrons, different isotopes react same way because they have same number of electrons

Question 19

Changes in different isotopes

Answer 19

Only physical changes:
- change of mass number
- higher mp/bp
- different density

Question 20

When something is hydrated ‘salt’

Answer 20

Water molecules are part of their crystalline structure, known as water of crystallisation

Question 21

How does percentage yield decrease

Answer 21

• reaction not going to completion (reversible)
• starts reacting differently (reacts with N2 in air instead of O2)
• products lost during filtration and movement

Question 22

Idea of atom economy

Answer 22

Awareness of dwindling finite resources and environmental concerns of disposing harmful waste

Question 23

How do you know smth is a salt

Answer 23

The H+ ions are replaced with e.g Na+ ions

Question 24

Preparing titration full steps

Answer 24

1. Measure accurately
2. Tip into beaker and follow up with water rinsing the boat
3. Stir with a rod until dissolved and transfer to volumetric flask, follow up with rinse of rod and beaker
4. Fill up water till meniscus of the graduated line and looking straight to avoid parallax error.
5. Put stopper, hold and invert to ensure fully mixed
6. To use, pour into beaker and use volumetric pipette to pull up certain vol and empty into beaker and tap to avoid any unmeasured vol entering

Question 25

How titration works

Answer 25

1. Make standard sols of acid and alkali 2. Add indicator in flask ( if alkali, it will be pink) 3. Run it until end point when colour change seen, swirling after each 4. Record and measure titre 5. Do rough titre 6. Measure until results are concordant (0.1 of each other)

Question 26

Special cases of oxidation numbers

Answer 26

H in metal hydrides = -1, e.g NaH or CaH2 O in peroxides = - 1, e.g. H2O2 O bonded to F = +2, e.g. F2O

Question 27

When naming molecules

Answer 27

USE ROMAN NUMERALS