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Chemistry is important because everything you do is chemistry! Even your body is made of chemicals. Chemical reactions occur when you breathe, eat, or just sit there reading. All matter is made of chemicals, so the importance of chemistry is that it's the study of everything..

Chemistry is important because everything you do is chemistry! Even your body is made of chemicals. Chemical reactions occur when you breathe, eat, or just sit there reading. All matter is made of chemicals, so the importance of chemistry is that it's the study of everything..

**Q1. If S+O**

SO

SO

H

Then the enthalpy of formation of H:

_{2}→SO_{2}; ∆H=-298.2 kJSO

_{2}+12O_{2}→SO_{3}; ∆H=-98.7 kJSO

_{3}+H_{2}O→H_{2}SO_{4}; ∆H=-130.2 kJH

_{2}+12O_{2}H_{2}O; ∆H=-287.3 kJThen the enthalpy of formation of H

_{2}SO_{4}at 298 K is
Solution

-650.3 kJ

-650.3 kJ

**Q2.**The products of combustion of an aliphatic thiol (RSH) at 298 K are

Solution

CO

CO

_{2}(g), H_{2}O(l), and SO_{2}(g)**Q3.**For hypothetical reversible reaction

1/2A

_{2}(g)+3/2B

_{2}(g)→AB

_{3}(g); ∆H=-20kJ if standard entropies of A

_{2},B

_{2}and AB

_{3}are 60, 40, and 50 J K

^{-1}mol

^{-1}, respectively. The above reaction will be equilibrium at

Solution

At equilibrium, ∆S

∴ S

At equilibrium, ∆S

_{Total}= 0∴ S

_{P}^{⊖}-S_{R}^{⊖}= 0

**Q4.**C

_{P}-C

_{V}=R. This R is

Solution

PV = RT at temperature T for one mole

PV+∆V=R(T+1) at temperature (T+1) for one mole

∴ P∆V = R

PV = RT at temperature T for one mole

PV+∆V=R(T+1) at temperature (T+1) for one mole

∴ P∆V = R

**Q5.**For which of the following equations, will ∆H be equal to ∆U?

Solution

∆H = ∆U+∆nRT

In (b), ∆n=0

∴ ∆H = ∆U

∆H = ∆U+∆nRT

In (b), ∆n=0

∴ ∆H = ∆U

**Q6.**A reaction, A+B⟶C+D+q, is found to have a positive entropy change, the reaction will be:

Solution

Possible at any temperature

Possible at any temperature

**Q7.**For the combustion reaction at 298 K

2Ag(s)+1/2O

_{2}(g)→2Ag

_{2}O(s)

Which of the following alternatives is correct?

Solution

∆H = ∆U+∆nRT

∆n = n

∴ ∆n = (2) - (5/2) = (-1/2)

∴ ∆H = ∆U - (1/2)RT

∴ ∆U = ∆H + (1/2)RT

Or ∴ ∆U > ∆H

∆H = ∆U+∆nRT

∆n = n

_{P}-n_{R}∴ ∆n = (2) - (5/2) = (-1/2)

∴ ∆H = ∆U - (1/2)RT

∴ ∆U = ∆H + (1/2)RT

Or ∴ ∆U > ∆H

**Q8.**Enthalpy of the system is given as

Solution

H = U + PV

H = U + PV

**Q9.**In thermodynamics, a process is called reversible when

Solution

The surroundings are always in equilibrium with the system

The surroundings are always in equilibrium with the system

**Q10.**For the reversible process, the value of ∆S is given by the expression

Solution

∆S=q

∆S=q

_{rev}/T