Final answer:
The reaction is not a redox reaction but a double-replacement reaction, where there is a formation of calcium phosphate, an insoluble compound. To react 1.36 moles of H3PO4, 2.04 moles of Ca(OH)2 are needed according to the stoichiometry of the balanced equation. Option b.
Step-by-step explanation:
The reaction given is 2H3PO4 + 3Ca(OH)2 → Ca3(PO4)2 + 6H2O, and it is not a redox reaction.
In redox reactions, the oxidation states of atoms change. However, in this case, there is no change in oxidation states of any of the elements involved.
The reaction is a double-replacement and precipitation reaction, where the cations and anions in the reactants switch partners to form new compounds, and one of the products is an insoluble solid (in this case, calcium phosphate).
Regarding the Check Your Learning exercise, to find out how many moles of Ca(OH)2 are required to react with 1.36 moles of H3PO4, we look at the stoichiometric coefficients from the balanced equation.
According to the equation 3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O, it takes 3 moles of Ca(OH)2 to react with 2 moles of H3PO4. Therefore, to react with 1.36 moles of H3PO4:
1.36 moles H3PO4 x (3 moles Ca(OH)2 / 2 moles H3PO4) = 2.04 moles Ca(OH)2So Option b.