Chapter 5 - Chemical Changes
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What is a displacement reaction?
• When a more reactive metal displaces a less reactive metal from an aqueous solution.
What is the reactivity series?
• A list of metal in order of reactivity, from most to least reactive.
Define oxidation and reduction. (Hint - OIL RIG)
• Oxidation is a gain of electrons. • Reduction is a loss of electrons.
State the definition of an ore.
• Metals within rocks that can be extracted economically. Include economically in your answer.
What reaction does magnesium give when a lighted splint is present in the hydrogen produced?
• A squeaky ‘pop’ sounds in the presence of hydrogen.
What is the role of hydrogen and carbon in the reactivity series?
• Used as reference and to see which metals can be extracted using either carbon or hydrogen.
What is an ionic equation and what is the metal which isn’t involved in the reaction called?
• An equation which only shows the atoms and ions changing in a reaction. • Spectator ions. (e.g 2 ions of NaOH means that NaOH would be removed from the ionic equation.)
What are half-equations used for?
• To show what happens to each reactant in an equation.
Write the ionic equation for the [displacement] of [copper (II)] ions by [iron]. Include state symbols.
Fe (s) + Cu2+ (aq) ———-> Fe2+ (aq) + Cu (s) (The iron has displaced the copper oxide, leaving iron oxide and copper)
Fe (s) + Cu2+ (aq) ———-> Fe2+ (aq) + Cu (s) Write a half equation to show what happened to the iron during the reaction. State whether it was reduction or oxidation.
Fe (s) ——–> Fe2+ (aq) + 2e- • It gained electrons, so it was a reduction.
Give 3 examples of metals which can be found in their native state.
• Gold • Silver • Platinum
Give the formula for the reduction of oxides by carbon.
Metal Oxide + Carbon —–> Metal + Carbon Dioxide
Define a strong acid.
• An acid which ionises completely. (releases H+ ions)
Define a weak acid.
• An acid which partially ionises. (Don’t fully release H+ ions).
Define the strength of an acid.
• How much an acid dissociates.
Define the concentration of an acid.
• Amount of acid per unit of volume.
What does a metal reacted with an acid always form?
• Salt + Hydrogen
Define the reactivity of a metal.
• How easily it can form positive ions.
RQP - A student wants to produce a soluble salt using some equipment and dilute HCl acid. Describe an experiment to obtain a soluble salt. [1]
• Place dilute acid in beaker and heat w/ bunsen burner. [1] • Gradually add an insoluble base. [1] • Eventually, the base no longer disappears. It is in excess. [1] • Filter out excess base using filter paper to obtain dissolved form of the soluble salt. [1]
Once the dissolved salt was obtained, the student was asked to obtain pure salt crystals from the dissolved salt. Suggest a way that he can do this.
• Evaporate off excess acid