Q) Drinking water may contain several unwanted ions such as phosphate ions. In order to remove the phosphate ions from the drinking water, a solution of calcium hydroxide can be added. As a result, a solid Ca5OH(PO4)3 is formed and isolated by filtration and a hydroxide ion are also formed. The reaction for this process is below: 5 Ca(OH)2 (aq) + PO43- (aq) → Ca5OH(PO4)3 (s) + OH- (aq) a) If 3.00 mL of 0.100 M calcium hydroxide is mixed with 4.00 mL of an aqueous solution of 0.0800 M phosphate ions (PO43-). What is the mass of Ca5OH(PO4)3 that can be isolated from the reaction? b) How many moles of the excess reactant remains unreacted? c) What is the concentration of the hydroxide ions in this solution? d) What is the mass of calcium (in grams) that can be recovered?
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
Q) Drinking water may contain several unwanted ions such as phosphate ions. In order to remove the phosphate ions from the drinking water, a solution of calcium hydroxide can be added. As a result, a solid Ca5OH(PO4)3 is formed and isolated by filtration and a hydroxide ion are also formed. The reaction for this process is below:
5 Ca(OH)2 (aq) + PO43- (aq) → Ca5OH(PO4)3 (s) + OH- (aq)
a) If 3.00 mL of 0.100 M calcium hydroxide is mixed with 4.00 mL of an aqueous solution of 0.0800 M phosphate ions (PO43-). What is the mass of Ca5OH(PO4)3 that can be isolated from the reaction?
b) How many moles of the excess reactant remains unreacted?
c) What is the concentration of the hydroxide ions in this solution?
d) What is the mass of calcium (in grams) that can be recovered?
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