Period 3 reactions Flashcards
Reaction of sodium with water
Na(s) + 2H2O → 2NaOH(aq) + H2(g)
Reaction of magnesium with water
Mg(s) + 2H2O(l) → Mg(OH)2 (aq) + H2(g)
Reaction of magnesium with steam
Mg + H2O → MgO + H2
Reaction of sodium with oxygen
2Na + 1/2O2 → Na2O
Reaction of magesium and oxygen
2Mg + O2 → 2MgO
Reaction of aluminium with oxygen
4Al + 3O2 → 2Al2O3
Reaction of silicon with oxygen
Si + O2 → SiO2
Reaction of phosphorous with oxygen
4P + 5O2 → P4O10
Reaction of sulphur with oxygen
S + O2 → SO2
What is the type of reaction that all period 3 elements undergo in oxygen or water?
Redox
Observations in reaction of sodium and water
Sodium floats on the surface
fizzing
(heat energy released)
Name the main product formed when sodium reacts with water and give its pH value
Sodium hydroxide
13-14
Does Na or Mg react faster with water?
Na
Why are very few bubbles seen when magnesium reacts with water?
Mg is sparingly soluble
Not all of it dissolves so less hydrogen produced
Name the main product formed when Mg reacts with water and give its pH
Mg(OH)2
pH = 10
Why does Mg react faster with steam than water?
Higher temp so more kinetic energy
Fully dissociates in steam
Are the reactions of period 3 with oxygen exothermic or endothermic?
Exothermic
Observation when Na reacts with oxygen
Burns with bright yellow flame to form white sodium oxide
Observation when Mg reacts with oxygen
Burns with bright white flame and produces white powder of MgO
Why does aluminium appear to be unreactive with air?
coated with protective layer of aluminium oxide
Al2O3 is impermeable to air/water
What are the conditions required fot the reaction of each type of phosphorous with oxygen?
red must be heated before it can react with oxygen
white ignites spontaneously in air
Why are there 2 forms of phosphorous and what are they?
Red and white phosphorous
Allotropes (same element, dfferent arrangment of atoms)
What colour is phosphorous pentoxide?
white
What product is formed if phosphorous reacts in a limited supply of oxygen?
Phosphorous trioxide
P2O3