PART - 1 CH - 5 Thermodynamics — Chemistry STD 11 Science — Question

1. Hydrolysis of sucrose give

$\text{Sucrose}+\text{H}_2\text{O}\rightleftharpoons\text{Glucose}+\text{Fructose}$

Equilibrium constant K_c for the reaction is 2 × 10¹³ at 300K. Calculate $\Delta\text{G}^\circ\text{ at }300\text{K.}(\log 2=0.3010)$

2. The concentration of hydrogen in two sample of soft drinks A and B 4.0 × 10^-7 and 3.2 × 10^-6 respectively. Which of these two soft drinks has higher pH?

1. Define standard enthalpy of formation. Explain why the enthalpy changes for the reaction given below are not enthalpies of formation of CaCO₃ and HBr:

1. $\text{CaO(s)}+\text{CO}_2(\text{g})\overrightarrow{\ \ \ \ \ \ \ \ }\ \text{CaCO}_3(\text{s});$ $\Delta_\text{r}\text{H}^\circ=-178.3\text{kJ mol}^{-1}$
2. ​​​​​​​$\text{H}_2(\text{g})+\text{Br}_2(\text{g})\overrightarrow{\ \ \ \ \ \ \ }\ 2\text{HBr(g)};$ $\Delta_\text{r}\text{H}^\circ=-72.8\text{kJ mol}^{-1}$

2. Use the bond enthalpies listed below to determine the enthalpy of reaction:

$\ \ \ \ \ \ \ \ \text{H}\\ \ \ \ \ \ \ \ \ \ |\\\text{H}-\text{C}-\text{H(g)}+2\text{O}=\text{O(g)}\overrightarrow{\ \ \ \ \ }\ \text{O}=\text{C}=\text{O(g)}\\ \ \ \ \ \ \ \ \ \ |\\ \ \ \ \ \ \ \ \ \text{H}\\+2\text{H}-\text{O}-\text{H(g)}$

Bond enthalpy $(\Delta\text{H}^\circ)/\text{kJ mol}^{-1}$ of C=O = 741; C-H = 414; H-O = 464; O=O = 498.