HARD
Earn 100

2 mol of Hg(g) is combusted in a fixed volume bomb calorimeter with excess of O2 at 298 K and 1 atm into HgO(s). During the reaction, temperature increases from 298.0 K to 312.8 K. If heat capacity of the bomb calorimeter and enthalpy of formation of Hg(g) are 20.00 kJ K-1 and 61.32 kJ mol-1 at 298 K, respectively, the calculated standard molar enthalpy of formation of HgO(s) at 298 K is X kJ mol-1. The value of|X| is ____. [Given: Gas constant R = 8.3 J K-1 mol-1]

Important Questions on Thermodynamics

EASY
Which of the following process best describes atomization of CH4g?
MEDIUM
A piece of metal weighing 100 g is heated to 80°C and dropped into 1 kg of cold water in an insulated container at 15°C. If the final temperature of the water in the container is 15.69°C, the specific heat of the metal in J/g°C. is
MEDIUM
When a 60 W electric heater is immersed in a gas for 100 s in a constant volume container with adiabatic walls, the temperature of the gas rises by 5°C. The heat capacity of the given gas is JK-1 (Nearest integer)
EASY
Which of the following relation is not correct?
EASY

The quantity of heat (in J) required to raise the temperature of 1.0 kg of ethanol from 293.45 K to the boiling point and then change the liquid to vapor at that temperature is closest to [Given, boiling point of ethanol 351.45 K. Specific heat capacity of liquid ethanol 2.44 J g-1 K-1. Latent heat of vaporisation of ethanol 855 Jg-1 ]

 

MEDIUM

A fish swimming in water body when taken out from the water body is covered with a film of water of weight 36 g. When it is subjected to cooking at 100 °C, then the internal energy for vaporization in kJmol-1 is integer]

[Assume steam to be an ideal gas. Given ΔvapH for water at 373 K and 1 bar is 41.1 kJ mol-1:R=8.31 J K-1 mol-1]

HARD

The molar heat capacity for an ideal gas at constant pressure is 20.785 J K-1 mol-1. The change in internal energy is 5000 J upon heating it from 300 K to 500 K. The number of moles of the gas at constant volume is____

(Given: R=8.314 J K-1 mol-1)

MEDIUM

The combination of plots which does not represent isothermal expansion of an ideal gas is

(A) Question Image

(B) Question Image

C Question Image

(D) Question Image

EASY
The difference between C¯p and C¯V is C¯p and C¯V signify molar quantities]
HARD

The specific heat of a certain substance is 0.86 J g-1 K-1. Assuming ideal solution behavior, the energy required (in J) to heat 10 g of 1 molal of its aqueous solution from 300 K to 310 K is closest to :

[Given: molar mass of the substance =58 g mol-1; specific heat of water =4.2 J g-1 K-1]

EASY
A piece of ice falls from a height h so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of h is:
(Latent heat of ice is 3.4×105J kg-1 and g=10N kg-1)
MEDIUM
At constant volume, 4 mol of an ideal gas when heated from 300K to 500K changes its internal energy by 5000J. The molar heat capacity at constant volume is ________
MEDIUM
The qualitative sketches I, II and III given below show the variation of surface tension with molar concentration of three different aqueous solutions of KCl, CH3OH  and CH3CH211OSO3- Na+ at room temperature. The correct assignment of the sketches is -

Question Image
EASY
At constant pressure, the heat of formation of a compound is not dependent on temperature, when
HARD
An ideal gas undergoes isothermal compression from 5 m3 to 1 m3 against a constant external pressure of 4 N m-2. The heat released in this process is 24 J mol-1K-1 and is used to increase the pressure of 1 mole of Al. The temperature of Al increases by:
HARD
Question Image
The above P-V diagram represents the thermodynamic cycle of an engine, operating with an ideal mono-atomic gas. The amount of heat, extracted from the source in a single cycle, is:
HARD
A reversible cyclic process for an ideal gas is shown below. Here, P, V, and T are pressure, volume and temperature, respectively. The thermodynamic parameters q, w, H and U are heat, work, enthalpy and internal energy, respectively.

Question Image

The correct option(s) is (are)
MEDIUM

200 mL of 0.2 M HCl is mixed with 300 mL of 0.1 M NaOH. The molar heat of neutralization of this reaction is -57.1 kJ. The increase in temperature in C of the system on mixing is x×10-2. The value of x is (Nearest integer)

[Given: Specific heat of water =4.18 J g-1 K-1 

Density of water=1.00 g cm-3]

(Assume no volume change on mixing)

MEDIUM
Two moles of helium gas is mixed with three moles of hydrogen molecules (taken to be rigid). What is the molar specific heat of mixture at constant volume? R=8.3 J/mol K
MEDIUM
X g of ice at 0oC is added to 340g of water at 20oC . The final temperature of the resultant mixture is 5oC . The value of X (in g) is closest to

[Heat of fusion of ice =333 J/g ; Specific heat of water =4.184 J/g.K ]