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Chemistry A level > Elements of the sea > Flashcards

Elements of the sea Flashcards

1
Q

Are nitrates & ethanoates soluble or insoluble?

A

All soluble

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2
Q

Are sulphates all soluble/insoluble and what are the exceptions

A

All soluble except from- Ba, Pb and Ca

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3
Q

Are halides soluble/insoluble and what are the exceptions?

A

All soluble apart from- Ag and Pb

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4
Q

Are carbonates soluble/insoluble and what are the exceptions?

A

All are insoluble apart from - Na, K and NH4

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5
Q

Are hydroxides soluble/insoluble and what are the exceptions?

A

All insoluble except from- Li, Na, K and Ca (sparingly soluble)

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6
Q

Are oxides soluble/ insoluble and what are the exceptions?

A

All insoluble (Gp1 and 2 react with water to produce hydroxides)

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7
Q

Write the ionic equation for:
Hydrochloric acid + sodium hydroxide —- sodium chloride + water

A

H+ + OH- —h20

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8
Q

What are the two mains way to prepare soluble salts

A

Titration = acid + alkali
Acid + insoluble base= crystallisation

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9
Q

How to test for insoluble salts

A

Precipitation reactions

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10
Q

Deduce the oxidation numbers of each element in these compounds:

LiAlH4
Na2O2
NaclO4

A

Li -+1
Al- +3
H- -1

Na - +1
O- -1

Na- +1
Cl- +7
O- -2

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11
Q

What is oxidation and reduction in redox reactions

A

Oxidation= gain of oxygen and loss of electrons (increase in oxidation number)

Reduction= loss of oxygen and gain of electrons (decrease in oxidation number)

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12
Q

What is an oxidising agent?

A

An element or compound that has caused the oxidation of another, it accepts electrons so therefore is reduced.

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13
Q

What is a reducing agent?

A

An element or compound that causes the reduction of another, it looses electrons and therefore is oxidised.

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14
Q

Define electronegativity and state the most electronegative element

A

Electronegativity is a measure of the ability of an atom to attract the bonding pair electrons in a covalent to itself.

The most electronegative atom is Fluorine.

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15
Q

State three physical properties of halogens

A

. Low melting and boiling points increases down group- increase in strength of intermolecular bonds
. Less volatile down the group
. solubility- non-polar molecules dissolve better in non-polar solvents

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16
Q

State the colour and state ofF2, Cl2, Br2 and I2 at rtp.

A

F2- very pale yellow gas
Cl2- pale green gas
Br2- brown/red liquid
I2- shiny grey solid

17
Q

State the colour of Cl2, Br2 and I2 at non-polar solvents and water

A

Cl2- pale green, very pale green

Br2- orange, yellow/orange

I2- purple, brown/yellow

18
Q

State chemical properties of redox reactions in general

A

. Halogens are oxidising agents so are reduced and oxidising strength decreases down the group
. Halide ions are reducing agents so are oxidised and reducing strength increases down group

19
Q

Describe the method to react halogens with halide ions (redox)

A
  1. Mix solution of halogen with halide ions
  2. add organic (non-polar0 solvent (cyclohexane) and shake
  3. The layers should separate
  4. The upper layer will be the halogen dissolved in the organic solvent
  5. use the colour as identification
20
Q

State the test for halide ions

A
  1. acidify with HNO3
  2. add aqueous AgNO3
  3. Observe the colour of the precipitate
  4. Add NH3 solution and shake
21
Q

State the four properties of hydrogen halides

A
  1. covalent molecules
  2. dissolve in water forms acidic solutions
  3. Halide ions act as reducing agent
  4. Reducing strength increases down the group
22
Q

Observation and equation of Sodium fluoride and sodium chloride

A

Observation: misty fumes of HF or HCL

Naf + H2SO4 -NaHSO4 + Hf
Nacl +H2SO4 -NaHSO4 +HCL

23
Q

Observation of NaBr and sulfuric acid and equation

A

Observation: Misty fumes of HBR and brown fumes (Br2)

2HBr + H2SO4 – SO2 + Br2 + 2H2O

24
Q

Reaction of NaI with sulfuric acid observation and equation

A

Observation: Misty fumes (HI) and a rotten egg smell

8HI + H2SO4– H2S + 4I2 + 4H2O

25
Q

What can be used as an alternative from sulfuric acid when reacted with hydrogen halides?

A

Phosphoric acid

26
Q

What happens at the anode?

A

Negative anions move towards the anode.
Negative ions lose electrons forming atoms (oxidised).

27
Q

What happens at the cathode.

A

Positive cations more towards cathode.
Positive ions gain electrons forming (reduced).

28
Q

State three properties of dynamic equilibrium

A
  1. rates of forwards= rates of backwards reaction
  2. concentrations of reactants and products remains constant
  3. only exists in closed systems
29
Q

What is Le Chatelier’s principle?

A

The position of equilibrium will shift so as to minimise the effect of any change in conditions.

30
Q

Summarise the effect of temperature on equilibrium

A

If forwards is exothermic= an increase of temp will shift it to left, decrease in temp will shift to right

If forwards is endothermic=
an increase in temp will shift to right, decrease in temp will shift left

31
Q

Summarise the effect of pressure on equilibrium

A

If forwards produces more moles of gas: shifts to left with less moles when increased pressure, decreased pressure will shift to right with more moles

Opposite if forward produces less moles.

32
Q

How to test for carbonates

A

Add an acid and if there is effervescence then CO32- ions are present. To prove this bubble it through limewater and it’ll turn cloudy.

33
Q

How to test for sulphate ions

A

Add nitric acid and barium nitrate solution. A white precipitate will form.

34
Q

How to test for halide ions

A

Add nitric acid and silver nitrate then a coloured precipitate will determine which halide is present. Then add ammonia to determine further.

35
Q

How to test for ammonium ions

A

Add sodium hydroxide and warm the mixture. Test it with red damp litmus paper and it’ll turn blue.

Chemistry A level (7 decks)

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