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Chemistry - norm > 1 - 2 Principles of Chemistry > Flashcards

1 - 2 Principles of Chemistry Flashcards

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1
Q

What does aqueous mean?

A

Dissolved in water

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2
Q

What are isotopes?

A

An element that has the same number of protons but different numbers of neutrons
- Same proton number but different mass numbers

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3
Q

What is the relative atomic mass?

A

Says how heavy the atom is compared with the mass of an atom of carbon-12 (Ar)

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4
Q

How do you work out the relative atomic mass?

A
  • State the mass of the isotopes
  • State the relative abundance
  • Multiply the mass by the relative abundance
  • Add together
  • Divide by the sum of the relative abundances
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5
Q

What is the relative abundance?

A

How much there is of each isotope compared to the total amount of element in the world
- Can be a fraction, percentage or ration

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6
Q

How do you work out the relative formula mass?

A

(Mr)

  • Add the atomic mass together
  • If there is more than one multiply (e.g. MgCl2 - multiply Cl by 2)
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7
Q

How do you work out the empirical formula?

A
  • List all the elements in the compound
  • Underneath write their experimental masses or percentages
  • Divide each mass or percentage by the relative atomic mass (Ar) for each element
  • Turn the numbers into a ratio
  • Put the ratio in the simplest form
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8
Q

How do you work out the empirical formula?

A
  • List all the elements in the compound
  • Underneath write their experimental masses or percentages
  • Divide each mass or percentage by the relative atomic mass (Ar) for each element
  • Turn the numbers into a ratio
  • Put the ratio in the simplest form
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9
Q

What is the empirical formula?

A

The simplest formula that tells you the ratio of different elements in the compound
The mass number tells you the actual number of each element

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10
Q

What is the equation for the percentage yield?

A

Actual yield (grams) / theoretical yield (grams) x100

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11
Q

How do you calculate masses in reactions>

A
  • Write out the balanced equation
  • For the two bits you want, work out the relative formula mass and multiply by the balancing numbers in the equation
  • Divide to get one
  • Multiply to get all
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12
Q

What is the equation for the number of moles?

A 
m = M / Mr
moles = mass (g) / Mr
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13
Q

What is the name of water in a lattice?

A

Water of crystallisation

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14
Q

What is the name of water in a lattice?

A

Water of crystallisation

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15
Q

Describe how to work out the amount of water lost in a salt

A
  • Work out the mass (with and without)
  • Calculate the number of water lost in moles (mass/Mr)
  • Calculate the amount of anhydrous salt lost in moles
  • Work out the ratio of made to lost
  • Divide to find 1 mole
  • Round to the nearest whole number
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16
Q

What is the equation for volume of a gas?

A

volume (dm3) = moles x 24

17
Q

What is the ratio of dm3 to cm3?

A

1dm3 = 1000cm3

18
Q

What is the equation for concentration?

A

Concentration (mol/dm3) = moles / volume

19
Q

How do you change mol/dm3 to g/dm3?

A
  • Work out the relative formula mass
  • Mass = mol x relative formula mass
  • Divide by how many moles you want
20
Q

How do you change mol/dm3 to g/dm3?

A
  • Work out the relative formula mass
  • Mass = mol x relative formula mass
  • Divide by how many moles you want
21
Q

What is the electricity flow?

A

The flow of electrons or ions

22
Q

When do ionic compounds conduct electricity?

A
  • Only when it is molten or in a solution as the electrons are free to move around
23
Q

Do covalent compounds conduct electricity?

A
  • No because they don’t contain ions as they’re electrons are shared
  • No carriers free to move to create an electric current
24
Q

How are metals held together?

A
  • By metallic bonding
  • Have a giant structure of positive electrons surrounded by delocalised electrons
  • Good conductors of heat and electricity
  • Most are malleable as atoms can slide over each other meaning they can be hammered or rolled into flat sheets
25
Q

How are metals held together?

A
  • By metallic bonding
  • Have a giant structure of positive electrons surrounded by delocalised electrons
  • Good conductors of heat and electricity
  • Most are malleable as atoms can slide over each other meaning they can be hammered or rolled into flat sheets
26
Q

What is electrolysis?

A
  • Used to make a new substance
  • Works by passing an electric current through an ionic substance that’s molten or in solution and breaking it into new substances
  • Needs an electrolyte
  • As ions gain or lose electrons they become atoms and molecules
27
Q

What is an electrolyte?

A
  • The liquid in electrolysis
  • Made by melting or dissolving ionic compounds
  • It is the free ions that conduct the electricity
28
Q

Describe electrolysis of molten lead

A

Electrolyte - molten lead bromide
Electrodes - carbon
Anode - Bromine is produced (2Br- –> Br2 + 2e-)
Cathode - Lead is produced (Pb2+ + 2e- –> Pb)

29
Q

Describe electrolysis of molten lead

A

Electrolyte - molten lead bromide
Electrodes - carbon
Anode - Bromine is produced (2Br- –> Br2 + 2e-)
Cathode - Lead is produced (Pb2+ + 2e- –> Pb)

30
Q

Electrolysis of an aqueous solution

A

Hydrogen and hydroxide ions will be produced

31
Q

What happens at the cathode in electrolysis of an aqueous solution?

A

If H+ ions and metal ions are present:

  • A more reactive metal ion will produce hydrogen gas will be produced
  • A less reactive metal ions a solid layer of pure metal will be produced
32
Q

What happens at the anode in electrolysis of an aqueous solution?

A
  • If OH- and halide ions are present halogen molecules will be formed
  • If no halide ions are present oxygen will be present
33
Q

Describe electrolysis of sulphuric acid

A
  • Hydrogen ions (from the water or sulphuric acid) accept electrons
  • At the cathode hydrogen gas is produced (2H+ +2e- –> H2)
  • Hydroxide ions lose electrons more easily than sulphate ions
  • At the anode oxygen and water are produced ( 4OH- –> O2 + 2H2O + 4e-)
34
Q

Describe electrolysis of sodium chloride

A
  • Hydrogen ions accept electrons more easily than sodium ions
  • At the cathode hydrogen gas is produced (2H+ + 2e- –> H2)
  • Chloride ions lose electrons more easily than hydroxide ions
  • At the anode chlorine gas is produced (2Cl- –> Cl2 + 2e-)
35
Q

Describe electrolysis of sodium chloride

A
  • Hydrogen ions accept electrons more easily than sodium ions
  • At the cathode hydrogen gas is produced (2H+ + 2e- –> H2)
  • Chloride ions lose electrons more easily than hydroxide ions
  • At the anode chlorine gas is produced (2Cl- –> Cl2 + 2e-)
36
Q

Describe electrolysis of copper(III) sulphate

A
  • Copper ions accept electrons more easily than hydrogen ions
  • At the cathode copper metal is produced (Cu2+ + 2e- –> Cu)
  • Hydroxide ions lose electrons more easily than sulphate ions
  • At the anode oxygen and water are produced (4OH- –> O2 + 2H2O + 4e-)
37
Q

How can you increase the amount of product made?

A
  • Increase the number of electrons
  • Electrolysing for longer
  • Increasing the current
38
Q

How do you calculate masses in electrolysis?

A
  • Write out the balanced half equation
  • Calculate the number of faradays (charge = current x time, charge / 96000)
  • Calculate the number of moles (faradays / number of electrons)
  • Mass = Mr x moles)

Chemistry - norm (6 decks)

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