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AS Chemistry > Group 2 and Group 7, Rates, Equilibria and Shapes. > Flashcards

Group 2 and Group 7, Rates, Equilibria and Shapes. Flashcards

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1
Q

Describe the trend in ionisation energy in group 2.

A

The ionisation energy decreases down the group.

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2
Q

Explain the trend in ionisation energy in group 2.

A

The ionisation energy decreases because the number of electron shells increases down the group, which increases:

  • shielding by inner inner shells of electrons
  • atomic radius

This makes it easier to remove the outer electron because it has less attraction to the nucleus.

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3
Q

What three substances do group 2 elements react with?

A

Water, oxygen and chlorine.

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4
Q

What three substances do group 2 elements react with?

A

Water, oxygen and chlorine.

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5
Q

What type of reaction takes place when group 2 elements react, considering they lose 2 electrons?

A

Oxidation

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6
Q

What is the general change in the oxidation number of group 2 elements when they react?

A

0 to 2+

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7
Q

What is the reaction between a group 2 element and water? (M = group 2 element)

A

M (s) + H20 (l) —> M(OH)2 (aq) + H2 (g)

A metal hydroxide and hydrogen are formed.

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8
Q

What is the trend in reactivity between group 2 elements and water?

A

The reactivity of group 2 elements increases down the group because their ionisation energies decrease.

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9
Q

What is the trend in reactivity between group 2 elements and water?

A

The reactivity of group 2 elements increases down the group because their ionisation energies decrease.

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10
Q

Describe the reactivity of Magnesium with water.

A

Magnesium reacts VERY SLOWLY with water.

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11
Q

Describe the reactivity of Strontium with water.

A

Reacts FAIRLY QUICKLY

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12
Q

Describe the reactivity of Barium with water.

A

Reacts RAPIDLY

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13
Q

Describe the reactivity of Beryllium with water.

A

Doesn’t react.

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14
Q

What is the reaction between a group 2 element and oxygen?

A

2M(s) + O2 (g) —-> 2MO (s)

A solid white oxide is produced.

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15
Q

What is the reaction between group 2 elements and chlorine?

A

M (s) + Cl2 (g) —> MCl2 (s)

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16
Q

The oxides of group 2 metals react readily with water to form _____ ______, which dissolve. The _________ ions make these solutions strongly alkali.

A

The oxides of group 2 metals react readily with water to form metal hydroxides, which dissolve. The hydroxide ions make these solutions strongly alkali.

17
Q

The oxides of group 2 metals react readily with water to form _____ ______, which dissolve. The _________ ions make these solutions strongly alkali.

A

The oxides of group 2 metals react readily with water to form metal hydroxides, which dissolve. The hydroxide ions make these solutions strongly alkali.

18
Q

Which group 2 oxide is an exception to the rule that the hydroxides produced when reacted with water are soluble?

A

Magnesium oxide. Its hydroxide reacts slowly and is not very soluble.

19
Q

What is the trend in the strength of the alkali produced in hydroxides of group 2 elements?

A

Oxides form stronger alkali solutions as you go down the group.

20
Q

What is the trend in solubility of group 2 hydroxides down the group?

A

The hydroxides get more soluble down the group.

21
Q

What is the trend in solubility of group 2 hydroxides down the group?

A

The hydroxides get more soluble down the group.

22
Q

What is the trend in solubility of compounds that contain double charged negative ions? (CO3 2-)

A

They decrease in solubility down the group.

23
Q

What is the trend in solubility of compounds that contain single charged negative ions? (OH-)

A

They increase in solubility down the group.

24
Q

Which group 2 sulphate is insoluble?

A

Barium sulphate

25
Q

Define activation energy.

A

The minimum amount of (kinetic) energy particles need to react.

26
Q

Which two things allow a reaction to take place between two particles?

A
  1. The direction of collision.

2. The energy that particles collide with.

27
Q

Define a catalyst.

A

A substance that lowers the activation energy of a reaction by providing an alternate pathway, without being used itself.

28
Q

Why does increasing the temperature increase the rate of a reaction?

A
  • At higher temperatures, particles have a higher average energy and will therefore move faster.
  • This means that the frequency of collisions between particles increase.
  • It also means that a higher proportion of particles will have an amount of (kinetic) energy equal to or greater than the activation energy, allowing them to react.
  • Therefore, a greater percentage of all collisions between particles will be successful.
29
Q

Why can a catalyst increase the rate of reaction?

A
  • A catalyst lowers the activation energy.
  • This means that a greater proportion of particles will have the amount of (kinetic) energy equal to or greater than the activation energy.
  • Therefore there are a greater proportion of successful collisions between particles.
30
Q

How can we measure the rate of reaction for gases?

A

A gas syringe can be used to collect gases produced, and the volume evolved can be recorded at regular intervals.

31
Q

How can we measure the rate of reaction for solids?

A

For reactions that produce precipitates or clouds, the rate can be measured by observing the visibility of a marker through the solution/precipitate. The time taken for the marker to disappear can be recorded for each different concentration/temperature, etc.

32
Q

What are homogeneous catalysts?

A

They are types of catalysts which are in the same state as the reactants of the reaction that they are catalysing.

33
Q

What do homogeneous catalysts do differently to normal catalysts?

A

They form intermediaries with the reactants and then the products are formed from the intermediate compounds. This is the alternative pathway.

34
Q

What do homogeneous catalysts do differently to normal catalysts?

A

They form intermediaries with the reactants and then the products are formed from the intermediate compounds. This is the alternative pathway.

35
Q

What differences will there be on the enthalpy profiles of homogeneously catalysed reactions and normally catalysed reactions?

A

There will be two bumps/peaks on the homogeneously catalysed reaction, but only one bump/peak on the normally catalysed reaction. This is because the homogeneously catalysed reactions involves the production of intermediates.

36
Q

How can we measure the rate of reaction for gases?

A
  • A gas syringe can be used to collect gases produced, and the volume evolved can be recorded at regular intervals.
  • The solution, in a beaker, can be placed on a weighing scale and the mass of the beaker and solution can be recorded at regular intervals. The mass would decrease as gas is produced. (for non-toxic gases)
37
Q

What differences will there be on the enthalpy profiles of homogeneously catalysed reactions and normally catalysed reactions?

A

There will be two bumps/peaks on the homogeneously catalysed reaction, but only one bump/peak on the normally catalysed reaction. This is because the homogeneously catalysed reactions involves the production of intermediates.

38
Q

Why does increasing the concentration increase the rate of reaction?

A
  • A higher concentration means that particles will be closer to each other.
  • If particles are closer to each other, they will collide with each other more often.
  • If particles collide more often, the frequency of successful collisions will increase.
39
Q

Why does increasing the surface area increase the rate of reaction?

A
  • A higher surface area means that more particles can come into contact with each other.
  • If more particles can come into contact with each other, the frequency of collisions will increase and therefore the frequency of successful collisions will also increase.

AS Chemistry (8 decks)

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