Which of the following reactions represents t | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(C) The standard heat of formation $(\Delta H_f^\circ)$ is defined as the enthalpy change when $1 	ext{ mole}$ of a compound is formed from its const

Vedclass · Accepted Answer

$\frac{1}{2} H_{2_{(g)}} + \frac{1}{2} Br_{2(\ell)} 	o HBr_{(g)}$

Vedclass · Answer

(C) The standard heat of formation $(\Delta H_f^\circ)$ is defined as the enthalpy change when $1 	ext{ mole}$ of a compound is formed from its constituent elements in their most stable standard states at $298 	ext{ K}$ and $1 	ext{ bar}$ pressure.In option $C$,$\frac{1}{2} H_{2_{(g)}} + \frac{1}{2} Br_{2(\ell)} 	o HBr_{(g)}$,$1 	ext{ mole}$ of $HBr$ is formed from its constituent elements ($H_2$ and $Br_2$) in their standard states ($H_2$ gas and $Br_2$ liquid). This satisfies the definition of standard heat of formation.Option $A$ involves a compound decomposing into an element.Option $B$ involves ions,not elements in their standard states.Option $D$ involves $P_4O_{11}$,which is not a standard stable oxide of phosphorus,and the stoichiometry does not form $1 	ext{ mole}$ of the product correctly.

Which of the following reactions represents the standard heat of formation of the product?

Similar Questions

Given that:
$C_{(s)} + O_{2(g)} \to CO_{2(g)}, \Delta H = -394 \ kJ$
$2H_{2(g)} + O_{2(g)} \to 2H_2O_{(l)}, \Delta H = -568 \ kJ$
$CH_{4(g)} + 2O_{2(g)} \to CO_{2(g)} + 2H_2O_{(l)}, \Delta H = -892 \ kJ$
Calculate the heat of formation of $CH_{4(g)}$ in $kJ$.

$H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(l)}$; $\Delta H$ at $298 \ K = -285.8 \ kJ$. The molar enthalpy of vaporization of water at $1 \ atm$ and $25^{\circ}C$ is $44 \ kJ$. The standard enthalpy of formation of $1 \ mole$ of water vapor at $25^{\circ}C$ is $...... \ kJ$. (in $.8$)

Given
$N_{2(g)} + 3H_{2(g)} \longrightarrow 2NH_{3(g)} \quad \Delta_{r}H^{\theta} = -92.4 \, kJ \, mol^{-1}$
What is the standard enthalpy of formation of $NH_{3}$ gas?

Given the following thermochemical equations:
$(i) \ Zn + \frac{1}{2}O_2 \rightarrow ZnO + 84000 \ cal$
$(ii) \ Hg + \frac{1}{2}O_2 \rightarrow HgO + 21700 \ cal$
Calculate the heat of reaction $(\Delta H)$ for the reaction: $Zn + HgO \rightarrow ZnO + Hg$. (in $cal$)

The heat of combustion of ethanol into carbon dioxide and water is $-327 \ kcal$ at constant pressure. The heat evolved (in $cal$) at constant volume and $27^{\circ} C$ (assuming all gases behave ideally) is $\left( R = 2 \ cal \ mol^{-1} \ K^{-1} \right)$

Vedclass Test Series

Exam Paper Generator

Online Exam Module