Understanding the Displacement of Silver
To determine the weight of silver displaced by a quantity of electricity that displaces 5600 ml of O2 at STP, we need to follow some key steps involving electrolysis and stoichiometry.

1. Volume of Oxygen
- At Standard Temperature and Pressure (STP), 1 mole of any gas occupies 22.4 liters (or 22400 ml).
- Thus, for 5600 ml of O2:
\[
\text{Moles of O}_2 = \frac{5600 \, \text{ml}}{22400 \, \text{ml/mol}} = 0.25 \, \text{mol}
\]

2. Electrochemical Reaction
- The reaction for the electrolysis of water can be represented as:
\[
2 \, \text{H}_2O \rightarrow 2 \, \text{H}_2 + \text{O}_2
\]
- From the above equation, 1 mole of O2 corresponds to 4 moles of electrons (since each water molecule requires 2 electrons for reduction).

3. Moles of Electrons
- Therefore, for 0.25 moles of O2:
\[
\text{Moles of electrons} = 0.25 \, \text{mol O}_2 \times 4 = 1.0 \, \text{mol electrons}
\]

4. Silver Displacement
- The reaction at the cathode when Ag+ is reduced to Ag is:
\[
\text{Ag}^+ + e^- \rightarrow \text{Ag}
\]
- Thus, 1 mole of electrons displaces 1 mole of silver.

5. Weight of Silver Displaced
- Molar mass of silver (Ag) = 107.87 g/mol.
- Therefore, the weight of silver displaced by 1 mole of electrons:
\[
\text{Weight of Ag} = 1 \, \text{mol} \times 107.87 \, \text{g/mol} = 107.87 \, \text{g}
\]
In conclusion, the weight of silver displaced by the electricity that displaces 5600 ml of O2 at STP is 107.87 grams.