Problem: Classify each reaction as spontaneous or nonspontaneous.Drag the appropriate items to their respective bins.Ca(s) + 2K+(aq) → Ca2+(aq) + 2K(s)3K(s) + Cr3+(aq) → 3K+(aq) + Cr(s) Cu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s)3Ni(s) + 2Cr3+(aq) → 3Ni2+(aq) + 2Cr(s)2Al(s) + 3Sn2+(aq) → 2Al3+(aq) + 3Sn(s)Au(s) + 3Li+(aq) → Au3+(aq) + 3Li(s)SpontaneousNonspontaneous

FREE Expert Solution

For Ca(s) + 2K+(aq) → Ca2+(aq) + 2K(s)

Step 1. Write the two half-cell reactions

Ca(s) → Ca2+(aq)

K+(aq) → K(s)


Step 2. Identify the oxidation half-reaction (anode) and the reduction half-reaction (cathode)

When a balanced reaction is given, identify the anode and the cathode half-reactions by determining the changes in oxidation states of each species based on the given reaction:

Recall:

Lose               Gain
Electron         Electrons
Oxidation       Reduction

cathode → reduction → oxidation number decreases

anode → oxidation → oxidation number increases

For ions: charge of the ion = oxidation number
For neutral atoms/compound: oxidation number = 0


Ca(s) → Ca2+(aq)
oxidation number increased → lost electrons → oxidized anode


K+(aq) → K(s)
oxidation number decreased reduced → cathode


Step 3. Determine the half-cell potentials (refer to the Standard Reduction Potential Table)

Ca2+(aq) + 2 e- → Ca(s)                        E°cell = – 2.76 V

K+(aq) + e- → K(s)                                    E°cell = – 2.92 V


Note that both reactions are written in the reduction half-reaction form because the reduction potentials given are for reduction half-reactions (from the standard reduction potential table). So, there’s no need to reverse the reactions or change signs.

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Problem Details

Classify each reaction as spontaneous or nonspontaneous.

Drag the appropriate items to their respective bins.

Ca(s) + 2K+(aq) → Ca2+(aq) + 2K(s)

3K(s) + Cr3+(aq) → 3K+(aq) + Cr(s) 

Cu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s)

3Ni(s) + 2Cr3+(aq) → 3Ni2+(aq) + 2Cr(s)

2Al(s) + 3Sn2+(aq) → 2Al3+(aq) + 3Sn(s)

Au(s) + 3Li+(aq) → Au3+(aq) + 3Li(s)

Spontaneous

Nonspontaneous

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Cell Potential concept. If you need more Cell Potential practice, you can also practice Cell Potential practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Hartman's class at MONTANA.