10. Group 2 Flashcards

1
Q

Reaction of Mg with oxygen

A
  • burns in oxygen on heating with a white flame

- white MgO solid formed

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2
Q

Reaction of Ca with oxygen

A
  • burns in oxygen on heating with a brick-red flame

- white CaO solid formed

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3
Q

Reaction of Sr with oxygen

A
  • burns in oxygen on heating with a red flame

- white SrO solid formed

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4
Q

Reaction of Ba with oxygen

A
  • burns in oxygen on heating with a green flame

- white BaO solid formed

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5
Q

Reaction of Mg with water

A
  1. reacts very slowly with cold water to form a white precipitate of Mg(OH)2
    - effervescence due to hydrogen gas
  2. reacts vigorously with steam and burns with a white flame to form white MgO solid
    - effervescence due to hydrogen gas
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6
Q

Reaction of Ca with water

A
  • forms a cloudy white suspension of slightly soluble Ca(OH)2 / water turns milky
  • bubbles produced
  • calcium sinks
  • calcium gets smaller / disappears
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7
Q

Reaction of Sr with water

A
  • faster bubbling
  • faster disappearance of Sr
  • no precipitate is formed in excess water
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8
Q

Reaction of Ba with water

A
  • even faster bubbling
  • even faster disappearance of Ba
  • no precipitate is formed in excess water
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9
Q

Reaction of Group 2 elements with dilute hydrochloric acid / dilute nitric acid

A
  • all react with dilute HCl/HNO3 to give bubbles of hydrogen and a colourless solution of the metal chloride / metal nitrate
  • reaction becomes more vigorous down the group
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10
Q

Reaction of Mg with dilute sulfuric acid

A
  • bubbles of hydrogen gas produced

- colourless solution of MgSO4 formed

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11
Q

Reaction of Ca with dilute sulfuric acid

A
  • some bubbles of hydrogen gas produced

- white precipitate of CaSO4 formed, which is sparingly soluble

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12
Q

Reaction of Sr with dilute sulfuric acid

A
  • very slight bubbles of hydrogen gas produced

- white precipitate of SrSO4 formed, which is insoluble

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13
Q

Reaction of Ba with dilute sulfuric acid

A
  • very slight bubbles of hydrogen gas produced

- white precipitate of BaSO4 formed, which is insoluble

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14
Q

Reaction of MgO with water

A
  • sparingly soluble / insoluble in water to form a white precipitate of Mg(OH)2 and a weakly alkaline solution, pH=9
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15
Q

Reaction of CaO with water

A
  • slightly soluble in water to form milky solution and an alkaline solution, pH=11
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16
Q

Reaction of SrO with water

A
  • soluble in water to form a colourless alkaline solution, pH=12
17
Q

Reaction of BaO with water

A
  • soluble in water to form a colourless alkaline solution, pH=13
18
Q

Reaction of Group 2 oxides with dilute hydrochloric acid / dilute nitric acid

A
  • all react with dilute HCl/HNO3 to give a colourless solution of the metal chloride / metal nitrate (and water)
19
Q

Reaction of MgO with dilute sulfuric acid

A
  • reacts to form a colourless solution of MgSO4
20
Q

Reaction of CaO with dilute sulfuric acid

A
  • reacts to form a white precipitate of CaSO4, which is sparingly soluble
21
Q

Reaction of SrO with dilute sulfuric acid

A
  • reacts to form a white precipitate of SrSO4, which is insoluble
22
Q

Reaction of BaO with dilute sulfuric acid

A
  • reacts to form a white precipitate of BaO, which is insoluble
23
Q

Behaviour of Group 2 hydroxides with water

Variation in solubility of the hydroxides

A
  • do not react with water
  • none of them are very soluble, but the solubility of the metal hydroxides increases down the group
  • alkalinity increases / stronger base down the group
24
Q

Reaction of Group 2 hydroxides with dilute acids

A
  • the hydroxides behave exactly like the oxides, forming salt and water (both oxides and hydroxides are basic)
25
Q

Behaviour of Group 2 carbonates with water

A
  • do not react with water

- all are insoluble in water

26
Q

Reaction of Group 2 carbonates with dilute hydrochloric acid / dilute nitric acid

A
  • all react with dilute HCl/HNO3 to give bubbles of carbon dioxide gas and a colourless solution of metal chloride / metal nitrate (and water)
27
Q

Reaction of Group 2 carbonates with dilute sulfuric acid

Variation in solubility of the carbonates

A
  • bubbles of CO2 gas produced
  • solubility of the metal carbonates decreases down the group
  • only MgSO4 is soluble, giving a colourless solution
  • the others form insoluble, white precipitates
28
Q

Thermal decomposition of Group 2 carbonates

A
  • decompose on heating to leave a metal oxide residue and CO2 gas (forms a white precipitate with limewater)
  • decomposition temperature / thermal stability increases down the group; ease of thermal decomposition decreases down the group
29
Q

Thermal decomposition of Group 2 nitrates

A
  • decompose on heating to leave a metal oxide residue, brown NO2 gas and O2 gas (relights glowing splint)
  • decomposition temperature / thermal stability increases down the group; ease of thermal decomposition decreases down the group
30
Q

Use of calcium hydroxide and calcium carbonate (powdered limestone) in agriculture

A
  • CaCO3 decomposes to form CaO (lime/quicklime)
  • CaO reacts with water in a hydration reaction to form Ca(OH)2 (slaked lime)
  • calcium hydroxide and calcium carbonate are used to reduce acidity in soil/increase pH of soil, as they are basic
  • but CaCO3 is more suitable b/c it is insoluble in water, so it is less likely to be washed away by rain
31
Q

Explain why there is no visible reaction when a piece of magnesium ribbon is exposed to the air. [2m]

A
  • activation energy is high

- so few/no particles with E >= Ea