Group 2 Flashcards
What is the trend in atomic radius in Group 2 elements?
Increases
More electron shells
So bigger atoms
What do the trend down the group of 1st ionisation energy in group 2?
Decrease.
Atoms get bigger
More shielding
Therefore weaker attraction from the nucleus to electron in outer shell
Trend in melting point in group 2
Decreases
Weaker metallic bonding
As metal ions are bigger
So lower melting points
What happens to group 2 metals when they burn in oxygen?
They burn and form metal oxides
For example, magnesium burns with a bright white flame to form magnesium oxide (MgO)
What is the chemical equation for the reaction of magnesium with oxygen?
2Mg + O2 → 2MgO
This reaction produces magnesium oxide, a white solid.
What is the melting point characteristic of magnesium oxide?
High melting point due to ionic bonding
MgO is an ionic compound formed from magnesium and oxygen.
How does the reactivity of group 2 metals change down the group?
Reactivity increases down the group
What happens to magnesium ribbon when it reacts with oxygen?
It forms a thin layer of magnesium oxide
This layer needs to be cleaned off before further reactions.
What effect does an un-cleaned Mg ribbon have on reaction rate tests with acid?
It gives a false result due to different reaction rates of Mg and MgO
What is the reaction equation for magnesium reacting with hydrochloric acid?
Mg + 2HCl → MgCl2 + H2
What is the reaction equation for magnesium oxide reacting with hydrochloric acid?
MgO + 2HCl → MgCl2 + H2O
What is the difference between magnesium’s reaction with steam and warm water?
Steam produces magnesium oxide and hydrogen with a flame; warm water produces magnesium hydroxide without a flame
What is the equation for magnesium reacting with steam?
Mg (s) + H2O (g) → MgO (s) + H2 (g)
What is the equation for magnesium reacting with warm water?
Mg + 2 H2O → Mg(OH)2 + H2
How do the other group 2 metals react with cold water?
They react with increasing vigour down the group to form hydroxides
What is the reaction equation for calcium reacting with cold water?
Ca + 2H2O (l) → Ca(OH)2 (aq) + H2 (g)
What is the reaction equation for strontium reacting with cold water?
Sr + 2 H2O (l) → Sr(OH)2 (aq) + H2 (g)
What is the reaction equation for barium reacting with cold water?
Ba + 2 H2O (l) → Ba(OH)2 (aq) + H2 (g)
What effect do the hydroxides produced from group 2 metal reactions have on water?
They make the water alkaline if they are soluble
What observable effects occur during the reaction of group 2 metals with water?
- Fizzing
- Metal dissolving
- Solution heating up
- White precipitate appearing (with calcium)
True or False: Magnesium reacts with warm water more vigorously than with steam.
False
What are the key properties of titanium that make it useful?
Abundant, low density, corrosion resistant
Titanium is used for making strong, light alloys, particularly in aircraft.
What is the first step in extracting titanium?
TiO2 (solid) is converted to TiCl4 (liquid) at 900°C
This conversion is essential for further purification and extraction processes.
How is TiCl4 purified?
By fractional distillation in an argon atmosphere
Argon is used to prevent contamination and reactions with moisture.
What is the temperature at which titanium is extracted using magnesium?
500°C
This temperature is necessary for the reaction between TiCl4 and Mg to occur efficiently.
Why is titanium extraction considered expensive?
Due to:
* Expensive cost of magnesium
* Batch process inefficiencies
* Cost of argon
* Need to remove moisture
* High temperatures required
These factors contribute to the overall cost despite titanium’s abundance.
What happens when titanium is attempted to be extracted with carbon?
Titanium carbide (TiC) is formed rather than titanium
This reaction prevents the successful extraction of pure titanium.
Why can’t titanium be extracted by electrolysis?
It must be very pure
Impurities can affect the electrolysis process and the quality of the titanium produced.
Fill in the blank: TiO2 + 2 Cl2 + 2 C → _______ + 2 CO
TiCl4
This reaction shows the conversion of titanium oxide to titanium tetrachloride.
Fill in the blank: TiCl4 + 2 Mg → Ti + _______
2 MgCl2
This reaction depicts the extraction of titanium using magnesium.
What is the state of TiO2 at room temperature?
Solid
It is ionic in nature.
What is the state of TiCl4 at room temperature?
Liquid
It is molecular, allowing for easier purification by fractional distillation.
What is the chemical formula for Magnesium Sulfate?
MgSO4
What is the chemical formula for Calcium Sulfate?
CaSO4
What is the chemical formula for Strontium Sulfate?
SrSO4
What is the chemical formula for Barium Sulfate?
BaSO4
What group do MgSO4, CaSO4, SrSO4, and BaSO4 belong to?
Group 2 sulphates
Which Group 2 sulfate is classified as soluble?
MgSO4
Which Group 2 sulfates are classified as slightly soluble?
CaSO4
Which Group 2 sulfates are classified as insoluble?
SrSO4, BaSO4
Complete the reaction: Ca2+(aq) + SO4^2-(aq) → _______
CaSO4(s)
Complete the reaction: Sr2+(aq) + SO4^2-(aq) → _______
SrSO4(s)
Complete the reaction: Ba2+(aq) + SO4^2-(aq) → _______
BaSO4(s)
What is the chemical formula for magnesium hydroxide?
Mg(OH)2
What is the chemical formula for calcium hydroxide?
Ca(OH)2
What is the chemical formula for strontium hydroxide?
Sr(OH)2
What is the chemical formula for barium hydroxide?
Ba(OH)2
Which group do Mg(OH)2, Ca(OH)2, Sr(OH)2, and Ba(OH)2 belong to?
Group 2 hydroxides
Are group 2 hydroxides generally soluble or insoluble?
Insoluble
What is the solubility of magnesium hydroxide?
Slightly soluble
What is the solubility of calcium hydroxide?
Soluble
Fill in the blank: The reaction for magnesium hydroxide formation is Mg2+(aq) + 2 OH-(aq) -→ _______.
Mg(OH)2(s)
Fill in the blank: The reaction for calcium hydroxide formation is Ca2+(aq) + 2 OH-(aq) -→ _______.
Ca(OH)2(s)
How does the solubility of Group II hydroxides change down the group?
Group II hydroxides become more soluble down the group.
What is the appearance of Group II hydroxides when not soluble?
All Group II hydroxides when not soluble appear as white precipitates.
Is magnesium hydroxide soluble in water?
Magnesium hydroxide is classed as insoluble in water.
What is the simplest ionic equation for the formation of Mg(OH)₂ (s)?
Mg²⁺ (aq) + 2OH⁻ (aq) → Mg(OH)₂ (s)
What pH does a suspension of magnesium hydroxide in water typically have?
A suspension of magnesium hydroxide in water will appear slightly alkaline (pH 9).
What medical uses does magnesium hydroxide have?
Magnesium hydroxide is used in medicine (in suspension as milk of magnesia) to neutralise excess acid in the stomach and to treat constipation.
What is the reaction of magnesium hydroxide with hydrochloric acid?
Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O
Why is magnesium hydroxide considered safe to use?
It is safe to use because it is so weakly alkaline.
How does calcium hydroxide’s solubility compare to that of magnesium hydroxide?
Calcium hydroxide is classed as partially soluble in water and will appear as a white precipitate.
What pH does a suspension of calcium hydroxide in water typically have?
A suspension of calcium hydroxide in water will appear more alkaline (pH 11).
What is lime water?
An aqueous solution of calcium hydroxide is called lime water.
What happens to lime water when carbon dioxide is bubbled through it?
The limewater turns cloudy as white calcium carbonate is produced.
What is the full equation for the reaction of calcium hydroxide with carbon dioxide?
Ca(OH)₂ (aq) + CO₂ (g) → CaCO₃ (s) + H₂O (l)
Is barium hydroxide soluble in water?
Barium hydroxide would easily dissolve in water.
What is the effect of barium hydroxide on the pH of a solution?
The hydroxide ions present would make the solution strongly alkaline.
What is the least soluble Group II sulfate?
BaSO₄ is the least soluble.
What is the full equation for the formation of barium sulfate precipitate?
SrCl₂ (aq) + Na₂SO₄ (aq) → 2NaCl (aq) + SrSO₄ (s)
What is the ionic equation for the formation of barium sulfate precipitate?
Sr²⁺ (aq) + SO₄²⁻ (aq) → SrSO₄ (s)
What is barium sulfate used for in medicine?
BaSO₄ is used in medicine as a ‘Barium meal’ for x-rays of the intestines.
Why is barium sulfate considered safe for use in medical imaging?
Its low solubility means it is not absorbed into the blood.
What happens when barium metal reacts with sulfuric acid?
It will only react slowly as the insoluble barium sulfate produced will cover the surface of the metal.
What reagent is used to test for sulfate ions?
BaCl₂ solution acidified with hydrochloric acid is used as a reagent to test for sulfate ions.
What indicates the presence of sulfate ions in a solution?
A white precipitate of barium sulfate forms.
What is the simplest ionic equation for the reaction of barium ions with sulfate ions?
Ba²⁺ (aq) + SO₄²⁻ (aq) → BaSO₄ (s)
What is the role of hydrochloric acid when testing for sulfate ions?
It reacts with carbonate impurities to prevent false results.
What would be observed if a carbonate was present during the sulfate test?
Fizzing due to CO₂ would be observed.
