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CHEMISTRY, M3 EQ-Bank 13

Explain how the trends in ionisation energy, atomic radius, and electronegativity across a period affect the reactivity of metals.   (3 marks)

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  • As you move across a period from left to right, the atomic radius decreases due to the increasing nuclear charge, which pulls the electrons closer to the nucleus.
  • This leads to an increase in ionisation energy, making it harder to remove an electron from a metal atom.
  • Additionally, electronegativity increases across the period, meaning that metals are less likely to lose electrons.
  • As a result, the reactivity of metals decreases across a period because it becomes more difficult for them to lose electrons and participate in chemical reactions.
Show Worked Solution
  • As you move across a period from left to right, the atomic radius decreases due to the increasing nuclear charge, which pulls the electrons closer to the nucleus.
  • This leads to an increase in ionisation energy, making it harder to remove an electron from a metal atom.
  • Additionally, electronegativity increases across the period, meaning that metals are less likely to lose electrons.
  • As a result, the reactivity of metals decreases across a period because it becomes more difficult for them to lose electrons and participate in chemical reactions.

CHEMISTRY, M3 EQ-Bank 11 MC

Which of the following trends explains why metals become more reactive as you move down a group in the periodic table?

  1. Increasing ionisation energy
  2. Increasing electronegativity
  3. Decreasing atomic radius
  4. Decreasing ionisation energy
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\(D\)

Show Worked Solution
  • As you move down a group in the periodic table, metals become more reactive because the ionisation energy decreases.
  • This means it requires less energy to remove the outermost electron. 
  • Lower ionisation energy is directly related to higher reactivity because metals more readily lose electrons in reactions, making them more reactive.

\(\Rightarrow D\)

CHEMISTRY, M3 EQ-Bank 10 MC

\begin{array} {|c|c|}
\hline
\rule{0pt}{2.5ex} \text{Standard potentials} \rule[-1ex]{0pt}{0pt} & \qquad E^{\circ}\ \text{V} \qquad\\
\hline
\rule{0pt}{2.5ex} \ce{Fe(s)/Fe^{2+}} \rule[-1ex]{0pt}{0pt} & -0.44 \\
\hline
\rule{0pt}{2.5ex} \ce{Ag(s)/Ag^{+}} \rule[-1ex]{0pt}{0pt} & 0.8 \\
\hline
\rule{0pt}{2.5ex} \ce{Zn(s)/Zn^{2+}} \rule[-1ex]{0pt}{0pt} & -0.76 \\
\hline
\rule{0pt}{2.5ex} \ce{Ni(s)/Ni^{2+}} \rule[-1ex]{0pt}{0pt} & -0.24 \\
\hline
\end{array}

Using the table above which would be the correct order of reactivity if the metals are ranked in order of decreasing electrochemical reactivity?

  1. \(\ce{Zn > Fe > Ni > Ag}\)
  2. \(\ce{Ag > Ni > Fe > Zn}\)
  3. \(\ce{Fe > Zn > Ni > Ag}\)
  4. \(\ce{Zn > Ni > Fe > Ag}\)
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\(A\)

Show Worked Solution
  • The more negative the \(E^{\circ}\) value, the higher the reactivity of the metal (tendency to lose electrons).
  • The order of metals from most reactive to least reactive is zinc (–0.76 V), iron (–0.44 V), nickel (–0.24 V), silver (0.8 V). 

\(\Rightarrow A\)

CHEMISTRY, M3 EQ-Bank 9 MC

For which pair of substances will a displacement reaction occur?

  1. Zinc in a solution of copper ions
  2. Silver in a solution of magnesium ions
  3. Copper in a solution of lead ions
  4. Iron in a solution of aluminium ions
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\(A\)

Show Worked Solution
  • When a more active metal is placed in a solution of less reactive metal ions, a displacement reaction will occur.
  • Using the standard potentials as a metal activity series, zinc is placed above copper and is therefore more reactive.

\(\Rightarrow A\)

CHEMISTRY, M3 EQ-Bank 7 MC

Metal Reaction when heated with oxygen Reaction when heated with water
\(\ce{Mg}\) \(\text{burns readily if powered to form oxides}\) \(\ce{\text{forms}\ OH\ \text{ions and hydrogen gas}}\)
\(\ce{Al}\) \(\text{reacts with steam to form oxide ions and hydrogen gas}\)
\(\ce{Zn}\)
\(\ce{Fe}\)

Using the table above, which of the following equations correctly represents the reaction of aluminium with water?

  1. \(\ce{Al(s) + H2O(l) -> Al(OH)3(aq) + H2(g)}\)
  2. \(\ce{2Al(s) + 3H2O(g) -> Al2O3(s) + H2(g)}\)
  3. \(\ce{Al(s) + 3H2O(l) -> Al(OH)3(aq) + 3H2(g)}\)
  4. \(\ce{2Al(s) + 3H2O(g) -> Al2O3(s) + 3H2(g)}\)
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\(D\)

Show Worked Solution
  • From the table, aluminium reacts with gaseous water to form aluminium oxide and hydrogen gas.

\(\Rightarrow D\)

CHEMISTRY, M3 EQ-Bank 7

Complete the table below, describing the reactivity characteristics of the three metals listed.    (3 marks)

\begin{array} {|l|l|l|l|}
\hline
 \ \ \ \ \textbf{Metal} \ & \ \ \ \ \textbf{Reactivity with} \ \ \ \ &\ \  \ \ \textbf{Reactivity with}\ \  \ \ & \ \  \ \ \textbf{Reactivity with}\ \ \ \ \ \  \\ & \ \ \ \ \ \ \ \ \ \ \ \textbf{water} & \ \ \ \ \ \ \ \ \textbf{dilute acid} & \ \ \ \ \ \ \ \ \textbf{oxygen}\\
\hline
\rule{0pt}{2.5ex}  \rule[-1ex]{0pt}{0pt} &  & & \\ \rule{0pt}{2.5ex} \text{Potassium (K)} \rule[-1ex]{0pt}{0pt} &  & & \\  & & & \\
\hline
\rule{0pt}{2.5ex}  \rule[-1ex]{0pt}{0pt} &  & & \\ \rule{0pt}{2.5ex} \text{Zinc (Zn)} \rule[-1ex]{0pt}{0pt} &  & & \\  & & & \\
\hline
\rule{0pt}{2.5ex}  \rule[-1ex]{0pt}{0pt} &  & & \\ \rule{0pt}{2.5ex} \text{Copper (Cu)} \rule[-1ex]{0pt}{0pt} &  & & \\  & & & \\
\hline
\end{array}

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\begin{array} {|l|l|l|l|}
\hline
 \ \ \ \ \textbf{Metal} \ & \ \ \ \ \textbf{Reactivity with} \ \ \ \ &\ \  \ \ \textbf{Reactivity with}\ \  \ \ & \ \  \ \ \textbf{Reactivity with}\ \ \ \ \ \  \\ & \ \ \ \ \ \ \ \ \ \ \ \textbf{water} & \ \ \ \ \ \ \ \ \textbf{dilute acid} & \ \ \ \ \ \ \ \ \textbf{oxygen}\\
\hline
 & \text{Violent reaction that} & \text{Highly exothermic,} & \text{Burns rapidly to form} \\  \text{Potassium (K)}  & \text{ignites hydrogen gas} & \text{ignition of the hydrogen} & \text{oxide which combusts}\\  & \text{produced.} & \text{produced.} & \text{spontaneously in air.} \\
\hline
 & \text{Reacts slower with no} & \text{Bubbles slowly to} & \text{Burns when heated with}  \\ \text{Zinc (Zn)}  & \text{combustion (can be sped} & \text{moderately with no} & \text{oxygen, forming a less} \\  & \text{up using steam).} & \text{ignition.} & \text{reactive oxide layer (may}\\ & & & \text{further react with water).} \\
\hline
 &  & & \text{Slowly reacts, producing}  \\  \text{Copper (Cu)}  & \text{No reaction.} & \text{No reaction.} & \text{highly stable oxide layer}  \\  & & & \text{that prevents further}  \\ & & & \text{oxidation.} \\
\hline
\end{array}

Show Worked Solution

\begin{array} {|l|l|l|l|}
\hline
 \ \ \ \ \textbf{Metal} \ & \ \ \ \ \textbf{Reactivity with} \ \ \ \ &\ \  \ \ \textbf{Reactivity with}\ \  \ \ & \ \  \ \ \textbf{Reactivity with}\ \ \ \ \ \  \\ & \ \ \ \ \ \ \ \ \ \ \ \textbf{water} & \ \ \ \ \ \ \ \ \textbf{dilute acid} & \ \ \ \ \ \ \ \ \textbf{oxygen}\\
\hline
 & \text{Violent reaction that} & \text{Highly exothermic,} & \text{Burns rapidly to form} \\  \text{Potassium (K)}  & \text{ignites hydrogen gas} & \text{ignition of the hydrogen} & \text{oxide which combusts}\\  & \text{produced.} & \text{produced.} & \text{spontaneously in air.} \\
\hline
 & \text{Reacts slower with no} & \text{Bubbles slowly to} & \text{Burns when heated with}  \\ \text{Zinc (Zn)}  & \text{combustion (can be sped} & \text{moderately with no} & \text{oxygen, forming a less} \\  & \text{up using steam).} & \text{ignition.} & \text{reactive oxide layer (may}\\ & & & \text{further react with water).} \\
\hline
 &  & & \text{Slowly reacts, producing}  \\  \text{Copper (Cu)}  & \text{No reaction.} & \text{No reaction.} & \text{highly stable oxide layer}  \\  & & & \text{that prevents further}  \\ & & & \text{oxidation.} \\
\hline
\end{array}

CHEMISTRY, M3 EQ-Bank 6

Metals such as Lead, Copper, Mercury and Silver do not react with dilute acids but will react with the same acids at higher concentration levels.

Explain why this occurs with reference to first ionisation energy.   (3 marks)

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  • First ionsiation energy refers to the energy required to remove a valence electron from a metal.
  • Metals react in their ionised state and the less energy that is required to reach this state, the more reactive the metal.
  • Lead, Copper, Mercury and Silver require more energy to remove their outer valence electrons and consequently are only reactive in the presence of stronger oxidising agents.
  • Concentrated acids have more oxidising ability than their dilute counterparts and can react with these metals.
Show Worked Solution
  • First ionsiation energy refers to the energy required to remove a valence electron from a metal.
  • Metals react in their ionised state and the less energy that is required to reach this state, the more reactive the metal.
  • Lead, Copper, Mercury and Silver require more energy to remove their outer valence electrons and consequently are only reactive in the presence of stronger oxidising agents.
  • Concentrated acids have more oxidising ability than their dilute counterparts and can react with these metals.

CHEMISTRY, M3 EQ-Bank 1 MC

In a laboratory, students reacted aluminium with water to produce an oxide and hydrogen gas.

Which of the following equations correctly represents this reaction.

  1. \(\ce{Al(s) + H2O(g) \rightarrow AlO(s) + H2(g)}\)
  2. \(\ce{2Al(s) + 3H2O(l) \rightarrow Al2O3(s) + H2(l)}\)
  3. \(\ce{Al(s) + 3H2O(g) \rightarrow AlO3(s) + H2(l)}\)
  4. \(\ce{2Al(s) + 3H2O(g) \rightarrow Al2O3(s) + H2(g)}\)
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\(D\)

Show Worked Solution
  • Aluminium is not reactive enough to form an oxide with liquid water over a short period. For this to occur additional energy needs to be input (eliminate B).
  • This can however be achieved by reacting the aluminium with steam, which has more energy than water.
  • Option D provides the only balanced equation of the remaining options.

\(\Rightarrow D\)

CHEMISTRY, M3 EQ-Bank 5

"The reason alkali metals produce ignition and the release of light and heat when reacting with cold water is due to the fact they have the energy to combust oxygen in the water".

Explain the validity of the statement with reference to metal reactivity.   (3 marks)

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The statement is partially correct.

  • Alkali metals have low first ionisation energies and are therefore extremely reactive which enables them to even react with even cold water.
  • However, the statement is incorrect about combustion. Metals and water react in the following generalised equation:
  •    \(\text{Metal + Water}\ \rightarrow\ \text{Metal hydroxide/oxide + Hydrogen gas} \)
  • Although oxygen can combust, the combustion occurring in the reaction of alkali metals is that of hydrogen, which is more flammable than oxygen and produced by the reaction.
  • This is consistent across all metals that react with water, although alkali metals are the only ones that contain enough energy to combust the hydrogen produced.
Show Worked Solution

The statement is partially correct.

  • Alkali metals have low first ionisation energies and are therefore extremely reactive which enables them to even react with even cold water.
  • However, the statement is incorrect about combustion. Metals and water react in the following generalised equation:
  •    \(\text{Metal + Water}\ \rightarrow\ \text{Metal hydroxide/oxide + Hydrogen gas} \)
  • Although oxygen can combust, the combustion occurring in the reaction of alkali metals is that of hydrogen, which is more flammable than oxygen and produced by the reaction.
  • This is consistent across all metals that react with water, although alkali metals are the only ones that contain enough energy to combust the hydrogen produced.

CHEMISTRY, M3 EQ-Bank 4

  1. Write the generalised equation for reactions between metals and dilute acids.   (1 mark)

  2. Provide one example of the generalised equation from part (a).   (1 mark)

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a.    \(\text{Metal + Dilute acid}\ \rightarrow\ \text{Salt + Hydrogen gas}\)

b.    One example (of many possible answers):

  • Magnesium reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas
  •    \(\ce{2Mg(s) + 2HCl(aq) -> 2MgCl + H2(g) } \)
Show Worked Solution

a.    \(\text{Metal + Dilute acid}\ \rightarrow\ \text{Salt + Hydrogen gas}\)

b.    One example (of many possible answers):

  • Magnesium reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas
  •    \(\ce{2Mg(s) + 2HCl(aq) -> 2MgCl + H2(g) } \)

CHEMISTRY, M3 EQ-Bank 3

  1. Write the generalised equation for reactions between metals and oxygen.   (1 mark)

  2. Provide one example of the generalised equation from part (a).   (1 mark)

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a.    \(\ce{Metal + Oxygen -> Metal oxide}\)

b.   One possible example (of many correct answers):

\(\ce{2Zn(s) + O2 -> 2ZnO(s)} \)

Show Worked Solution

a.    \(\ce{Metal + Oxygen -> Metal oxide}\)
 

b.   One possible example (of many correct answers):

\(\ce{2Zn(s) + O2 -> 2ZnO(s)} \)