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AS Chemistry > group 2 > Flashcards

group 2 Flashcards

1
Q

What is formed when group 2 elements react with

oxygen?

A

Group 2 metal oxide

This is a redox reaction

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2
Q

What is observed when group 2 elements react with

oxygen?

A

● Beryllium only reacts in powdered form.
● Magnesium burns with an intense white flame.
● Calcium burns with a bright white flame (red at the
top).
● Strontium is reluctant to start burning but burns
intensely with a white flame.
● Barium burns with a white flame.

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3
Q

Write an equation for the reaction between calcium

and oxygen

A

Ca(s) + ½O2(g) → CaO(s)

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4
Q

How do group 2 elements react with water?

A

An alkaline hydroxide and hydrogen gas

This is a redox reaction

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5
Q

Describe the trend in the reactions with water as you

go down group 2

A

As you go down the group, the reactions

become more vigorous.

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6
Q

Write an equation for the reaction between strontium

and water

A

Sr + 2H2O → Sr(OH)2 + H2

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7
Q

Why does beryllium only react with steam at very

high temperatures and not with cold water?

A

Because beryllium is the least reactive

group 2 metal.

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8
Q

Why does magnesium stop reacting with cold water

after a short time?

A

Because an insoluble coat of magnesium

hydroxide forms on the surface.

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9
Q

What is formed when group 2 elements react with

dilute acids?

A

A salt and hydrogen gas

This is a redox reaction

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10
Q

Write an equation for the reaction between

magnesium and hydrochloric acid

A

Mg + 2HCl → MgCl2 + H2

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11
Q

Describe the trend in the reactivity of group 2 metals

with hydrochloric acid

A

Reactivity increases / the reactions get

more vigorous.

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12
Q

Describe and explain the trend in the reactivity of

group 2 metals with sulfuric acid

A

The reactions do not get more vigorous down the group due to the solubility of
the sulfates produced.

  • Beryllium and magnesium: soluble sulfates so similar reaction as with HCl
  • Calcium: sparingly soluble sulfate
  • Strontium and barium: insoluble sulfates

Calcium, strontium and barium only react with sulfuric acid for a short time as
the formation of the insoluble sulfate on the metal stops the reaction.

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13
Q

Why might a precipitate be seen when a group 2

oxide reacts with water?

A 
Group 2 hydroxides are only slightly 
soluble in water so when the solution is 
saturated, the metal hydroxide doesn’t 
dissolve (meaning it appears as a 
precipitate).
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14
Q

Write an equation for the reaction between calcium

oxide and water

A

CaO(s) + H2O(l) → Ca(OH)2(aq)

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15
Q

Describe the trend in the solubility of group 2

hydroxides. Use this to explain the trend in pH

A

The solubility of group 2 hydroxides
increases down the group. As a result,
more OH- ions are release in solution
meaning pH increases down the group.

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16
Q

Which group 2 oxide doesn’t react with water?

A

Beryllium oxide

17
Q

What is formed when group 2 oxides react with dilute

acids?

A

A salt and water

18
Q

Write an equation for the reaction between barium

oxide and hydrochloric acid

A

BaO + 2HCl → BaCl2 + H2O

19
Q

How do group 2 hydroxides behave in water? Use

Ca(OH)2 as an example

A

Group 2 hydroxides dissociate in water
to form their constituent ions:

         2+       - Ca(OH)2(s) → Ca (aq) + 2OH (aq)
20
Q

What is formed when group 2 hydroxides react with

dilute acids?

A

A salt and water

E.g. Ca(OH)2 + 2HCl → CaCl2 + 2H2O

21
Q

How do group 2 carbonates behave in water?

A

All group 2 carbonates are sparingly
soluble in water. They do not react with
water.

22
Q

What is formed when group 2 carbonates react with

dilute acids?

A

A salt, water and carbon dioxide gas

23
Q

Write an equation for the reaction between

magnesium carbonate and nitric acid

A

MgCO3 + 2HNO3 → Mg(NO3)2 + CO2 + H2O

24
Q

Describe how group 2 nitrates thermally decompose

A

Upon heating, group 2 nitrates
decompose to form a group 2 metal
oxide, nitrogen dioxide and oxygen gas.

25
Q

Write an equation for the thermal decomposition of

strontium nitrate

A

Sr(NO3)2 → SrO + 2NO2 + ½O2

26
Q

Describe the thermal decomposition of group 2

carbonates

A

Upon heating, group 2 carbonates decompose to
form a group 2 oxide and carbon dioxide.

E.g. CaCO3 → CaO + CO2

27
Q

What is the use of Ca(OH)2 and CaCO3 in agriculture?

A

● Both compounds can be added to soil to raise the pH
so that it is not too acidic to grow crops. This is
because they react with and neutralise acids.

● CaCO3 is used in the manufacture of quicklime,
slaked lime, cement and mortar.

● Ca(OH)2 is used for cement, mortar and sewage
treatment.

AS Chemistry (22 decks)

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