Tag: chemical thermodynamics

Quizzes (7) Questions (120)

Questions Related to chemical thermodynamics

Multiple choice chemistry occurrence of carbon compounds in nature calorific value study of enthalpy chemical thermodynamics

Which one of the following has the highest calorific value?

  1. Kerosene

  2. Biogas

  3. LPG

  4. Petrol
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The calorific value of a fuel is the quantity of heat produced by its combustion - at constant pressure and under a conditions known as " normal " of temperature and pressure (i.e. to 0oC and under a pressure of 1,013 mbar). 
The combustion of a fuel product generates water vapor. Certain techniques are used to recover the quantity of heat contained in this water vapor by condensing it. 
The Higher Calorific Value (or Gross Calorific Value - GCV) supposes that the water of combustion is entirely condensed and that the heat contained in the water vapor is recovered. 
The Lower Calorific Value (or Net Calorific Value - NCV) supposes that the products of combustion contains the water vapor. The heat contained in the water vapor is not recovered. 
LPG has a typical specific calorific value of 46.1 MJ/kg.
Calorific value of Bio gas is about 19 to 25 MJ/cubic meter, depending on the methane percentage in the biogas mix.
Heat of combustion of kerosene for lower heating value is 43.1 MJ/kg, and for higher heating value is 46.2 MJ/kg.
Petrol, calorific value of which is 45.8 MJ/kg.
Thus, LPG has highest calorific value among above.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

The following two equilibria exist simultaneously in a closed vessel :
$PCI _5(g) \rightleftharpoons PCI _3(g) + Cl _2(g)$
$COCI _2(g) \rightleftharpoons CO (g) + CI _2 (g)$
If some CO is added into the vessel, then after the equlibrium is attained again, concertration of ?

  1. $PCI _5$ will increase
  2. $PCI _5$ will decrease
  3. $PCI _5$ will remain unaffected
  4. $CI _2$ will increase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given reactions are,

$PCl _5 \rightleftharpoons PCl _3+Cl _2$
$COCl _2\rightleftharpoons CO _{(g)}+Cl _2$
If some $CO$ is added into the vessel, the concentration of $PCl _5$ will remain unaffected, because $CO$ reacts with $Cl _2$ and forms $COCl _2$, not going to effect the concentration of $PCl _5$ .

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Bond dissociation enthalphies of ${ H } _{ 2 }\left( g \right) $ and ${ N } _{ 2\left( g \right)  }$ are enthalpy of formation of $N{ H } _{ 3 }\left( g \right) $ is $-46 kJ mol^{-1}$. What is enthalpy of atomization of $N{ H } _{ 3 }\left( g \right) $?

  1. $390.3 kJ mol^{-1}$
  2. $1170.9kJ mol^{-1}$
  3. $590 kJ mol^{-1}$
  4. $720 kJ mol^{-1}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

Identify the 'State function' among the following

  1. q
  2. q $\times$ W

  3. q/W

  4. q + W
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Both work and heat are path functions. Their values depends on the path chosen to reach a particular state.
However, the change in internal energy which is equal to the sum of heat and work, is a state function. Its value is independent of  the path chosen to reach a particular state.

Multiple choice chemistry chemical thermodynamics system and surroundings introduction to thermodynamics basics of thermodynamics

An isolated system is one which neither shows an exchange of _nor _with surroundings.

  1. heat, mass

  2. heat, temperature

  3. temperature, mass

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Heat, mass

In physical science, an isolated system is either 

(1) a thermodynamic system which is completely enclosed by walls through which can pass neither matter nor energy, though they can move around inside it; or 

(2) a physical system so far removed from others that it does not interact with them.

Hence, option A is correct.