Question

# 3.An aqueous solution of Na3PO4 is heated from 24.7o C to 35.6o C. How much heat...

3.An aqueous solution of Na3PO4 is heated from 24.7o C to 35.6o C. How much heat was absorbed by the solution?

1. Consider the chemical equation below. Is the reaction endothermic or exothermic? Explain your answer. HCl(aq) + NaOH(aq) J NaCl(aq) + H2O(l) -56.13 kJ

2. In the reaction in question 1, how many kJ of energy are produced when 0.041 moles of HCl are neutralized by an excess of NaOH?

(3) The amount of heat absorbed by the solution , Q = mcdt

Where

m = mass of the solution =

c = specific heat capacity of Na3PO4 solution = 4.057 J/g-oC

dt = change in temperature = final - initial = 35.6 - 24.7 = 10.9 oC

If we know the mass of the solution we have to fing the amount of the solution.

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(1) HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l) H = -56.13 kJ

Here the change in enthalpy is -ve that means heat is released so the reaction is exothermic reaction.

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(2) From the above balanced reaction ,

1 mole of HCl reacts with excess NaOH produces 56.13 kJ of heat

0.041 mole of HCl reacts with excess NaOH produces M kJ of heat

M = ( 0.041 x 56.13) / 1

= 2.30 kJ

Therefore the amount of energy produced is 2.30 kJ

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