ThermochemistryHard

Question

Calculate the heat effect produced when a solution of 1 mole of ethanol in 5 moles of water is mixed with a solution of 2 moles of ethanol in 20 moles of water.

C2H5OH + 5H2O → C2H5OH (5H2O): ΔH = −1120 cal

C2H5OH + 10H2O → C2H5OH (10H2O): ΔH = −1760 cal

C2H5OH + (25/3)H2O → C2H5OH (25/3 H2O): ΔH = −1650 cal

Options

A.310 cal is absorbed.
B.310 cal is released.
C.4640 cal is absorbed.
D.4640 cal is released.

Solution

$3C_{2}H_{5}OH + 25H_{2}O \rightarrow 3C_{2}H_{5}OH\left( 25H_{2}O \right);$

$\Delta H_{\text{theo}} = ( - 1120) + 2( - 1760) = - 4640\text{ kcal}$

$\Delta H_{\text{theo}} = 3( - 1650) = - 4950\text{ cal}$

As experimentally, more heat is released means the mixing is exothermic by (4950 – 4640) = 310 cal.

Create a free account to view solution

View Solution Free
Topic: Thermochemistry·Practice all Thermochemistry questions

More Thermochemistry Questions

The ΔGo values for the hydrolysis of creatine phosphate (creatine-P) and glucose-6-phosphate (G-6-P) are(i) Creatine-P +...The enthalpy of combustion at 25°C of H2(g), cyclohexane(l) and cyclohexene(l) are −241, −3920 and −3800 kJ/mol, respect...For the given two processes(i) ½P4(s) + 3Cl2(g) → 2PCl3(l): ΔH = −635 kJ (ii) PCl3(l) + Cl2(g) → PCl5(s): ΔH = −137 kJth...Among the following the reaction for which ΔH = ΔE, is...Enthalpies of solution of BaCl2(s) and BaCl2·2H2O(s) are −20.6 kJ/mol and 8.8 kJ/mol, respectively. ΔH hydration of BaCl...