CHEMISTRY · Multi-part · CBSE · Chemistry · Some Basic Concepts of Chemistry · Some Basic Concepts of Chemistry
Problem
In a qualitative-analysis experiment, a student slowly adds 50.0mL of 0.200M phosphoric acid, H3PO4(aq), to 100.0mL of 0.300M calcium hydroxide, Ca(OH)2(aq), with constant stirring at room temperature. A white solid forms immediately and the final mixture is heterogeneous.
(a) Phosphoric acid is triprotic. Write the overall balanced molecular equation (including physical states) that accounts for all acid-base and precipitation processes occurring when the two solutions are combined.
(b) Express the reaction from part (a) as a complete ionic equation, explicitly showing each step of the acid’s dissociation that is relevant to the reaction.
(c) Derive the net ionic equation for the reaction, clearly indicating the precipitate that forms.
(d) Show, with calculations, which reactant is the limiting reagent and determine the theoretical mass of solid product formed (molar mass of calcium phosphate = 310gmol−1). Use appropriate significant figures.
(e) Describe a particulate-level representation of the mixture after the reaction has gone to completion, specifying the relative amounts and physical states of all species present.