reactions of period 3 elements with oxygen and water

how does Na react with water?

• floats on and moves about surface of water

• fizzes and melts to form a silvering ball

• eventually disappears and solution remaining is colourless

give the eqn for the reaction of Na with water:

2Na _(s) + 2H₂O _(l) → 2NaOH _(aq) + H_{2 (g)}

how does Mg react with water?

• reacts v slowly w/ water

• will produce a small vol of hydrogen when left in contact w/ water for several weeks :(

give the eqn for Mg reacting with water:

Mg _(s) + 2H₂O _(l) → MgOH_{2 (aq)} + H_{2 (g)}

how does Mg react with water vapour?

• reacts vigorously with water vapour at temps > 100 ^oC (373K) in absence of air

• forms a white solid and bright flame

give the eqn for Mg’s reaction with water vapour:

Mg _(s) + H₂O _(g) → MgO _(s) + H_{2 (g)}

give the observation and the eqn for the reaction of sodium with oxygen:

• yellow flame observed, white solid formed

• 4Na + O₂ → 2Na₂O

give the observation and the eqn for the reaction of magnesium with oxygen:

• burns in air - white light observed and white solid formed

• 2Mg + O₂ → 2MgO

give the explanation for the reaction of aluminium with oxygen:

• aluminium powder reacts readily

• but aluminium foil does not react as easily - has protective oxide layer which prevents reaction with oxygen and water, ∴ preventing corrosion

give the eqn for the reaction of aluminium with oxygen:

4Al + 3O₂ → 2Al₂O₃

give the explanation and eqn for the reaction of silicon with oxygen:

• finely /ed silicon reacts with oxygen when heated, forming silicon dioxide

• Si + O₂ → SiO₂

give the explanation and eqn for phosphorous reacting in limited oxygen:

P₄ + 3O₂ → P₄O₆

give the explanation and eqn for phosphorous reacting in XS oxygen:

P₄ + 5O₂ → P₄O₁₀

give the observation and eqn for sulfur’s initial reaction with oxygen:

• burns in air - yellow solid sulfur melts to form a red liquid

• this then burns with a blue flame, forming misty fumes of a choking, pungent gas

• S + O₂ → SO₂

give the eqn for sulfur’s further reaction with oxygen and state the conditions:

• 2SO₂ + O₂ → 2SO₃

• more oxygen, vanadium (V) oxide catalyst, specific temp/pressure conditions

how do halogens react w/ oxygen?

form unstable oxides

do noble gases react with oxygen?

no - inert