Reactions Of Period 3 Oxides Flashcards
(52 cards)
Why does magnesium oxide form an Alkaline solution when it reacts with water
Hydroxide ions are released
What bonding is found in basic oxides
ionic bonding
Give two examples of basic oxides
Sodium oxide and Magnesium oxide
Give the equation for the reaction of sodium oxide with water and the resulting pH
Na2O + H2O -> 2NaOH
pH - 14
Give the equation for the reaction of magnesium oxide with water and give the pH of the result
MgO + H2O -> Mg(OH)2
pH - 9
Describe a test you would carry out in a test tube to distinguish between sodium oxide and magnesium oxide
React each metal oxide with water
Measure pH with a pH meter
Explain the reason for the difference in the pH of the solutions formed when both basic oxides react with water
-Sodium hydroxide is more soluble in water so higher concentration of hydroxide ions released
-Magnesium hydroxide is slightly soluble in water so lower concentration of hydroxide ions released
What would you expect the pH of Ca(OH)2 to be. Explain why
More soluble than Mg(OH)2 so pH is greater than Mg(OH)2
What is the role of water and oxide in the reaction between basic oxides and water
Water : Acid
Oxide : Base
State the bonding in basic oxides. Explain why this type of binding causes these oxides to have basic properties
-Ionic bonding
-Contains oxide ions (O²-)
-These oxide ions react with H2O to form OH-
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What must happen to metal and non metal atoms to form giant ionic lattices
Metals form positive ions by losing electrons
Non metals form negative ions by gaining electrons
What factors affect the strength of an ionic bond
Ionic charge
Size of ion
Outline an experiment that could be used to show that metal oxides contain ions
MELT until metal oxide is molten
After it is molten, it will conduct electricity
Explain why does MgO have a higher metling point than Na2O
-Mg²+ has a higher charge than Na+
-Mg²+ is a smaller ion than Na+ (same number of electrons but Mg has a higher nuclear charge)
-Stronger attraction between Mg²+ and O²- ions than Na+ and O²- ions
Explain why Al2O3 has a lower melting point than MgO
- Al³+ has a higher charge than Mg²+
- Charge on Al³+ polarises O²- ions
- Al2O3 has same covalent character
What is the relationship between difference in electronegativity and ionic character
The greater the difference in electronegativity the greater the ionic character
What is the relationship between difference in electronegativity and covalent character
The smaller the difference in electronegativity the more covalent the character
Explain why SiO2 has a higher melting point than other non metal oxides
Macromolecular
Lots of strong covalent bonds
Large amounts of energy required to break
Explain why P4O10 has a higher mp than SO3
They are both simple molecular structures
P4O10 is a larger moelcule than SO3
Stronger VDW forces between P4O10 molecules than SO3 molecules
More energy needed to overcome forces between P4O10 moelcules than SO3 molecules
Explain the term amphoteric
Reacts with acids and bases
What is the only period 3 oxide that is amphoteric
Aluminium oxide
Why is aluminium oxide amphoteric
It’s Insoluble in water because it has covalent character and water can’t break its bonds
When aluminium oxide reacts with water, why is the resulting pH 7
Aluminium oxide is Insoluble so it can’t dissociate to form H+ or OH- ions
