PART - 1 CH - 2 Structure of Atom — Chemistry STD 11 Science — Question

1. Heat(q) and work done (W) individually are not state functions but their sum is always a state function. Explain why?
2. Calculate the standard enthalpy change $(\Delta_\text{r}\text{H}^\theta)$ and standard internal energy change $(\Delta_\text{r}\text{U}^\theta)$ for the following reaction at 300K:

OF₂(g) + H₂O(g) + O₂(g) + 2HF(g)

Standard enthalpy of formation $(\Delta_\text{r}\text{H}^\theta)$ of e n various species are given below:

$\Delta_\text{f}\text{H}^\theta\text{kJ mol}^{-1}:$ OF₂(g) = 23.0, H₂O(g)= -241.8, HF(g) = -268.6, R = 8.314 JK^-1mol^-1.

1. Arrange the following according to given property

$\text{CH}_3\stackrel{\oplus \ \ \ }{\text{CH}}_2,\text{C}_6\text{H}_5-\stackrel{\oplus\ \ \ \ }{\text{CH}}_2,(\text{CH}_3)_3\stackrel{\oplus \ \ \ \ }{\text{CH}},$

$\text{CH}_2=\text{CH}-\stackrel{\oplus\ \ \ \ }{\text{CH}}_2$ (decreasing order of stability)

2. $\text{HC}\equiv\text{C}^{\ominus},\text{Ch}_2=\stackrel{\ominus\ \ \ \ \ \ }{\text{CH}_2},\text{CH}_3-\stackrel{\ominus\ \ \ \ \ }{\text{CH}_2},\stackrel{\ominus \ \ \ \ \ }{\text{CH}_3}$ (increasing order of stabillity)

3. $\text{C}_6\text{H}_5\stackrel{\bf. \ \ \ \ }{\text{CHCH}_3},\text{C}_6\text{H}_5\text{CH}_2\stackrel{\bf.\ \ \ \ \ }{\text{CH}_2},\text{C}_6\text{H}_5\stackrel{\bf.}{\text{C}}_3(\text{CH}_3)_2$ (increasing order of stabillity)

4. $\text{CH}_3-\stackrel{\oplus \ \ \ \ }{\text{CH}}-\text{O}-\text{CH}_3,\text{CH}_3-\stackrel{\oplus \ \ \ \ }{\text{CH}},-\text{OCH}_3,$

${\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{O}}\\{\ \ \ \ \ \ \ \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ \|}\\\ \text{CH}_3-\stackrel{\oplus \ \ \ \ }{\text{CH}}\text{C}-\text{OCH}_3$ (decreasing order of stability)