The strongest reducing agent in an aqueous solution from the provided metals is identified by examining their standard reduction potentials. A reducing agent facilitates oxidation by donating electrons. The more negative the standard reduction potential, the stronger the reducing agent.
| Metal | Standard Reduction Potential (V) |
|---|---|
| Potassium (K) | -2.93 |
| Sodium (Na) | -2.71 |
| Barium (Ba) | -2.90 |
| Lithium (Li) | -3.04 |
Although Lithium's very negative potential might suggest it as a candidate, practical observations in aqueous solutions, considering metallic properties and solvation, establish potassium as the most potent reducing agent among these options.
Consequently, within an aqueous environment, Potassium (K) functions as the most effective reducing agent.
The freezing point depression constant (\( K_f \)) for water is \( 1.86 \, {°C·kg/mol} \). If 0.5 moles of a non-volatile solute is dissolved in 1 kg of water, calculate the freezing point depression.