211.
Fixed mass of an ideal gas contained in a $$24.63\,L$$ sealed rigid vessel at $$1\,atm$$ is heated from $$ - {73^ \circ }C$$ to $${27^ \circ }C.$$ Calculate change in gibb's energy if entropy of gas is a function of temperature as $$S = 2 + {10^{ - 2}}T\left( {J/K} \right):\,\left( {{\text{Use}}\,1\,atm\,L = 0.1\,kJ} \right)$$
212.
A given mass of gas expands from state $$A$$ to state $$B$$ by three paths 1, 2, and 3 as shown in the figure :
If $${w_1},{w_2}$$ and $${w_3}$$ respectively, be the work done by the gas along three paths, then
Work is equal to area under $$P - V$$ graph ( when $$P$$ is plotted along $$y$$ - axis ). As area under graph 3 is maximum and area under graph 1 is minimum, so $${w_3}$$ is minimum and $${w_1}$$ is minimum.
$$\therefore \,\,{w_1} < {w_2} < {w_3}$$
213.
How many molecules of $$ATP,$$ undergo hydrolysis to raise the temperature of $$180\,kg$$ of water which was originally at room temperature by $${1^ \circ }C?C\left\{ {P,m} \right\}$$ water $$ = 75.32\,J/mol/K,\,\Delta H\left\{ P \right\}$$ for $$ATP$$ hydrolysis $$= 7 kcal/mol$$
214.
The amount of energy released when $$20\,mL$$ of $$0.5\,M\,NaOH$$ are mixed with $$100\,mL$$ of $$0.1\,M\,HCl$$ is $$x\,kJ.$$ The heat of neutralisation $$\left( {{\text{in}}\,\,kJ\,mo{l^{ - 1}}} \right)$$ is
In question $$0.01\,gev$$ of $$NaOH$$ is being neutralised by $$0.01\,gev$$ of $$HCl$$ and value is $$x\,kJ,$$ for $$1\,gev$$ the value is $$ - 100x$$ ( exothermic process ).
215.
For which one of the following equations $$\Delta H_r^ \circ $$ equal to $$\Delta H_f^ \circ $$ for the product?
A
$$Xe\left( g \right) + 2{F_2}\left( g \right) \to Xe{F_4}\left( g \right)$$
B
$$2CO\left( g \right) + {O_2}\left( g \right) \to 2C{O_2}\left( g \right)$$
C
$${N_2}\left( g \right) + {O_3}\left( g \right) \to {N_2}{O_3}\left( g \right)$$
D
$$C{H_4}\left( g \right) + 2C{l_2}\left( g \right) \to C{H_2}C{l_2}\left( l \right) + 2HCl\left( g \right)$$
Answer :
$$Xe\left( g \right) + 2{F_2}\left( g \right) \to Xe{F_4}\left( g \right)$$
When one mole of a substance is directly formed from its constituent elements, then the enthalpy change is called heat of formation.
For the reaction,
$$\eqalign{
& Xe\left( g \right) + 2{F_2}\left( g \right) \to \mathop {Xe{F_4}\left( g \right)}\limits_{1\,\,mol} \cr
& \Delta {H^ \circ }_{{\text{react}}} = \Delta H_f^ \circ \cr} $$
216.
An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If $${T_i}$$ is the initial temperature and $${T_f}$$ is the final temperature, which of the following statements is correct?
A
$${\left( {{T_f}} \right)_{rev}} = {\left( {{T_f}} \right)_{irrev}}$$
B
$${T_f} = {T_i}$$ for both reversible and irreversible processes
C
$${\left( {{T_f}} \right)_{irrev}} > {\left( {{T_f}} \right)_{rev}}$$
D
$${T_f} > {T_i}$$ for reversible process but $${T_f} = {T_i}$$ for irreversible process
NOTE : In a reversible process the work done is greater than in irreversible process. Hence the heat absorbed in reversible process would be greater than in the latter case. So
$${T_f}\left( {rev.} \right) < {T_f}\left( {irr.} \right)$$
217.
What is the free energy change $$'\Delta G'$$ when $$1.0\,mole$$ of water at $${100^ \circ }C$$ and $$1\,atm$$ pressure is converted into steam at $${100^ \circ }C$$ and $$1\,atm.$$ pressure
$${q_2}$$ is heat of neutralization of strong acid with strong base and $${q_1}$$ is that of weak acid $$HA$$ with strong base. The difference gives the heat of dissociation of $$HA$$ i.e.,
$$\eqalign{
& \Delta H = \Delta {H_2} - \Delta {H_1} \cr
& \,\,\,\,\,\,\,\,\,\,\, = \left( { - {q_2}} \right) - \left( { - {q_1}} \right) \cr
& \,\,\,\,\,\,\,\,\,\,\, = {q_1} - {q_2} \cr} $$
219.
Gasoline has an enthalpy of combustion $$24000\,kJ/gallon.$$ When gasoline burns in an automobile engine, approximately $$30\% $$ of the energy released is used to produce mechanical work. The remainder is lost as heat transfer to the engine's cooling system. As a start on estimating how much heat transfer is required, calculate what mass of water could be heated from $${25^ \circ }C$$ to $${75^ \circ }C$$ by the combustion of 1.0 gallon of gasoline in an automobile?
$$\left( {{\text{Given}}:C\left( {{H_2}O} \right) = 4.18\,J/{g^ \circ }C} \right)$$
For monoatomic gas $${C_v} = \frac{3}{2}\,R\,{C_p} = \frac{5}{2}\,R$$
At constant volume, $$\Delta U = {q_v} = n{C_{v,m}}\,\Delta T$$
At constant pressure, $$\Delta H = {q_p} = n{C_{p,m}}\,\Delta T$$