The following reactions occur spontaneously as written:
2Cr^{2+}(aq) + Co^{2+}(aq) → 2Cr^{3+}(aq) + Co(s)
Co(s) + Pb^{2+}(aq) → Co^{2+}(aq) + Pb(s)
Fe(s) + 2Cr^{3+}(aq) → Fe^{2+}(aq) + 2Cr^{2+}(aq)
Using this information, predict which one of the following pairs of reactants will react spontaneously - VCE - SSCE Chemistry - Question 17 - 2008 - Paper 1
Question 17
The following reactions occur spontaneously as written:
2Cr^{2+}(aq) + Co^{2+}(aq) → 2Cr^{3+}(aq) + Co(s)
Co(s) + Pb^{2+}(aq) → Co^{2+}(aq) + Pb(s)
Fe(s) + 2Cr^{3... show full transcript
Worked Solution & Example Answer:The following reactions occur spontaneously as written:
2Cr^{2+}(aq) + Co^{2+}(aq) → 2Cr^{3+}(aq) + Co(s)
Co(s) + Pb^{2+}(aq) → Co^{2+}(aq) + Pb(s)
Fe(s) + 2Cr^{3+}(aq) → Fe^{2+}(aq) + 2Cr^{2+}(aq)
Using this information, predict which one of the following pairs of reactants will react spontaneously - VCE - SSCE Chemistry - Question 17 - 2008 - Paper 1
Step 1
A. Co(s) + Fe^{2+}(aq)
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Answer
To determine if these reactants will react spontaneously, we need to look at the potential for Co(s) to reduce Fe^{2+}(aq). Co is below Fe in the activity series, meaning it cannot reduce Fe^{2+}(aq) spontaneously.
Step 2
B. Cr^{2+}(aq) + Fe^{2+}(aq)
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Answer
Cr^{2+}(aq) can reduce Fe^{2+}(aq) as Cr is a stronger reducing agent. However, it depends on the specific standard reduction potentials which are not provided, so further analysis is necessary, but generally, it is not favorable spontaneously.
Step 3
C. Cr^{2+}(aq) + Pb^{2+}(aq)
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Answer
Based on the provided reactions, Cr^{2+}(aq) can reduce Pb^{2+}(aq) because Pb is lower in activity than Cr, thus indicating that this reaction occurs spontaneously.
Step 4
D. Pb(s) + Co^{2+}(aq)
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Answer
Pb(s) cannot react spontaneously with Co^{2+}(aq) since Pb is a weaker reducing agent compared to Co, as seen in the provided equations.
