16 Questions
What influences the acidic or basic behavior of an oxide?
The metallic character of the element it is bonded to
Which type of oxides are formed when non-metal elements combine with oxygen?
Acidic oxides
What type of oxides do metals typically form?
Basic oxides
What is the defining characteristic that distinguishes acidic and basic oxides?
Their values of pH
Which type of element is most likely to create an acidic oxide?
Non-metal
What type of oxides are formed when a metal element combines with oxygen?
Basic oxides
Which group of oxides can behave as both acidic and basic?
Amphoteric oxides
When dissolved in water, what type of solution do basic oxides produce?
Basic solution
What happens when amphoteric oxides react with acids?
They produce salt and water
Which theory can identify acids or bases in situations where substances exhibit both acidic and basic behavior?
Lewis acid-base theory
Which of the following elements exhibits amphoteric behavior with its oxide?
Aluminum (Al)
What is the purpose of leaving the filtrate in a warm place to dry and crystallize?
To evaporate excess water
Which compound is formed when copper(II) oxide reacts with sulfuric acid?
Copper(II) sulphate
What will happen if copper(II) oxide is added in insufficient amounts to the sulfuric acid?
The copper(II) oxide will be in excess
Which type of base is copper(II) oxide referred to as in the given procedure?
Insoluble base
What gas is produced during the reaction of copper(II) oxide and sulfuric acid?
Hydrogen
Study Notes
Insoluble Base Preparation
- Copper(II) oxide is an insoluble base
- To prepare it, add dilute sulfuric acid to a beaker and heat it using a bunsen burner flame
- Add copper(II) oxide a little at a time to the warm dilute sulfuric acid and stir until the copper(II) oxide is in excess
- Filter the mixture into an evaporating basin to remove the excess copper(II) oxide
- Leave the filtrate in a warm place to dry and crystallize
- Decant excess solution and blot crystals dry with filter paper
Equation of Reaction
- Copper(II) oxide + sulfuric acid → copper(II) sulphate + water
- CuO (s) + H2SO4 (aq) → CuSO4 (aq) + H2O (l)
Classifying Oxides
- Oxides are compounds made from one or more atoms of oxygen combined with one other element
- Examples of oxides include: MgO, ZnO, K2O, CO2, SO2, H2O
Acidic Oxides
- Acidic oxides are formed when a non-metal element combines with oxygen
- They react with bases to form a salt and water
- When dissolved in water, they produce an acidic solution with a low pH
- Common examples include CO2, SO2, NO2, and SiO2
Basic Oxides
- Basic oxides are formed when a metal element combines with oxygen
- They react with acids to form a salt and water
- When dissolved in water, they produce a basic solution with a high pH
- Common examples include CuO and CaO
Neutral Oxides
- Neutral oxides do not react with either acids or bases
- Examples include N2O, NO, and CO
Amphoteric Oxides
- Amphoteric oxides can behave as both acidic and basic, depending on whether the other reactant is an acid or a base
- In both cases, salt and water are formed
- Two common amphoteric oxides are zinc oxide (ZnO) and aluminum oxide (Al2O3)
- Examples of aluminum oxide behaving as a base and an acid:
- Al2O3 + 6HCl → 2AlCl3 + 3H2O (base)
- Al2O3 + 2NaOH → 2NaAlO2 + H2O (acid)
Test your knowledge on classifying oxides based on their acid-base characteristics. Identify examples of acidic and basic oxides and understand their properties and pH values.
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