Calorimetry

Q. Two spheres made of same substance have diameters in the ratio 1 : 2. Their thermal capacities are in the ratio of

1. 1:8
2. 1:4
3. 1:2
4. 2:1

Q. How much heat energy is gained when $5kg$ of water at ${20}^{\circ }C$ is brought to its boiling point?
$(\text{Specific heat of water}=4.2kJk{g}^{-1}{c}^{-1})$

1. $1740kJ$

2. $1680kJ$

3. $1700kJ$

4. $1720kJ$

Q.

The specific latent heat of vaporization of water is ________.

Q.

A body of mass 2 kg is being dragged with uniform velocity of 2 m/s on a rough horizontal plane. The coefficient of friction between the body and the surface is 0.20. The amount of heat generated in 5 sec is (J =4.2 joule/cal and g=9.8 $m/s^2$)

1. 13.34 cal

2. 9.33 cal

3. 10.21 cal

4. 12.67 cal

Q. 27.the heat liberated on complete combustion of 1 mole of CH4 gas to CO2 and H2O is 890kJ. Calculate heat evolved by 2.4 l of CH4 on complete combustion

Q. 42. Standard enthalpies of combustion of C2H4(g), C2H6(g) and H2(g) are –1410.8, –1559.8 and –285.9 kJ mol–1 at constant pressure and 298 K respectively. What is the enthalpy of hydrogenation of C2H4(g) at constant volume and at 298 K?

Q. 18 Two conducting rods are joined in series as shoin the diagram Their conductivity are K and 2KTheir length are in the ratio 2L and L respectivelyIf extreme ends are maintained at 100C and 0Cthen the junction temperature T is (Assume onedimensional steady state heat tranisfer)100C2 L(1) 80 C(3) 40 C(2) 60C(4) 20C

Q. The combustion enthalpies of carbon, hydrogen, and methane are -395.5 kJ mol^{-1}, -284.8 kJ mol^{-1} and -890.4 kJ mol^{-1} respectively at 25^0C. The value of s†an dard formation enthalpies of methane at that temperature is (1) 890.4 kJ mol^{-1} (2)-298.8 kJ mol^{-1} (3) -74.7 kJ mol^{-1} (4) -107.7 kJ mol^{-1}

Q. By blowing air in soap bubble the radius is increased from 2r to 3r then percentage increase in surface energy of bubble is

Q. The energy required to blow a bubble of radius 4cm & 3cm in the same liquid in the ratio of: (a). 3:4 (b). 16:9 (c). 64:27 (d). 27:64

Q. If a gas absorbs 100J of heat and expands by 500cm^3 against a cons†an t pressure of 2×10^5Nm^{-2}, the change in internal energy is:

Q. The reaction:- NH2CN(s)+ 3/2O2(g)---->N2(g)+ CO2(g)+ H2O(l) was carried out in a bomb calorimeter. The heat released was 743KJ/mol. Find the value of delta(H)300K for this reaction. 1) -740.5 KJ/mol 2) -741.75 KJ/mol 3) -743 KJ/mol 4) -744.25 KJ/mol

Q. 19. (i) What is residual entropy? (ii) Standard enthalpy of combustion.

Q.

When heat in given to a gas in an isobaric process, then

1. The work is done by the gas

2. Internal energy of the gas increases

3. Both (a) and (b)

4. None from (a) and (b)

Q. (3) 128It is given that the specific heat of copper is onetenth that of water A copper ball of 100 g at 200^° Cis put into 100 cc water at 24^° C. Assuming noheat loss to the surroundings. The final(4) 138^° temperature of the system is7(2) 55^° C(1) 60%C(4) 35^° C3)40^° C

Q. 2.1 g of graphite is burnt in a bomb calorimeter in excess of oxygen at 298K and 1 atmospheric pressure .During the reaction, temperature rises from 298K to 299K. If the heat capacity of the bomb calorimeter is 20.7kJ/K, what is the enthalpy change for the above reaction at 298k and 1 atm?

Q. An ice cube contains a large air bubble. The cube is floating on the horizontal surface of water. What will happen to the water level when ice melt

Q. What is the dimensional formula for thermal resistance? (1)\lbrack M^{-1} L^{-2} T^{-1} K\rbrack (2)\lbrack ML^2 T^{-2} K^{-1} (3)\lbrack ML^{-3}T^2K^{-1}\rbrack (4)\lbrack M^{-1}L^{-2}T^3K

Q. 26.The dimensional formula for thermal resistance is?

Q. How much heat must be removed by a refrigerator from $4\text{kg}$ of water at ${70}^{\circ }\text{C}$ to convert it to ice cube at $-{10}^{\circ }\text{C}$ ?
[Take specific heat of water $C_w=4200{\text{J/kg/}}^{\circ }\text{C}$, Latent heat of fusion of ice$L_f=334000\text{J/kg}$, Specific heat of ice $C_i=2100\text{J/kg K}$]

1. $3521\text{kJ}$
2. $2596\text{kJ}$
3. $2352\text{kJ}$
4. $4200\text{kJ}$

Q. The graph shows the variation of temperature (T ) of one kilogram of a material with the heat (H) supplied to it. At O, the substance is in the solid state rom the graph, we can conclude that

1. BC represents the change of state from solid to liquid
2. is the melting point of the solid
3. represents the latent heat of fusion of the substance
4. represents the latent heat of vaporization of the liquid

Q. In an experiment on the specific heat of a metal, a 0.20 kg block of the metal at 150 °C is dropped in a copper calorimeter (of water equivalent 0.025 kg) containing 150 cm3 of water at 27 °C. The final temperature is 40 °C. Compute the specific heat of the metal. If heat losses to the surroundings are not negligible, is your answer greater or smaller than the actual value for specific heat of the metal ?

Q. $0.93\text{watt-hour}$ of energy is supplied to a block of ice at $0^{\circ }\text{C}$, weighing $10\text{g}$. It is found that-
[Latent heat of fusion of ice, $L=80\text{cal/g}$]

1. Block of ice melts completely.
2. Block of ice does not melt.
3. Block of ice melts partially.
4. Data insufficient

Q.

A lead bullet penetrates into a solid object and melts. Assuming that 50% of its kinetic energy was used to heat it, calculate the initial speed of the bullet. The initial temperature of the bullet is ${27}^{\circ }C$ and its melting point is ${327}^{\circ }C$. Latent heat of fusion of lead = $2.5\times {10}^{4}Jk{g}^{-1}$ and specific heat capacity of lead = $125Jk{g}^1{K}^1$.

1. 500 m/s

2. 5000 m/s

3. 100 m/s

4. 1000m/s

Q. A system expands from 2L volume to 10L volume against an external pressure of 1 bar when 300J of heat is supplied to it. What is the change in internal energy of the system

Q. $1\text{kg}$ of ice at $-{10}^{\circ }\text{C}$ is mixed with $4.4\text{kg}$ of water at ${30}^{\circ }\text{C}$. The final temperature of mixture is

Given specific heat of ice $=0.5{\text{cal/g}}^{\circ }\text{C}$,
Specific heat of water $=1{\text{cal/g}}^{\circ }\text{C}$,
Latent heat of fusion for ice $=80\text{cal/g}$.

1. ${2.3}^{\circ }\text{C}$
2. ${4.4}^{\circ }\text{C}$
3. ${5.3}^{\circ }\text{C}$
4. ${8.7}^{\circ }\text{C}$

Q. a gas occupies 2litre volume at STP. it is provided 300 joule heat so that its volume becomes 2.5 litre at 1 atm. change in its internal energy will be (a)239joules (b)205 joules (c)249.37 joules (d)220.37 joules

Q. the heat of combustion of sucrose C_{12}H_{22}O_{11} at cons†an t volume is -1348.9kcalmol^{-1 }at 25^° C, then the heat of reaction at cons†an t pressure i

Q.

Calculate the amount of heat required to convert 1.00 kg of ice at -10°C at normal pressure to steam at 100°C. Specific heat capacity of ice = 2100 J kg⁻¹ K⁻¹ , latent heat of fusion of ice = 3.36 × 10⁵ J kg⁻¹ , specific heat capacity of water = 4200 J kg ⁻¹ K⁻¹ and latent heat of vaporization of water = 2.25 × 10⁶ J kg⁻¹

1. $3.03\times {10}^{6}J$
2. $3.03\times {10}^{12}J$
3. $3.303\times {10}^{-6}J$
4. $3.303\times {10}^{5}J$

Q. A 10 kW drilling machine is used to drill a bore in a small aluminium block of mass 8.0 kg. How much is the rise in temperature of the block in 2.5 minutes, assuming 50% of power is used up in heating the machine itself or lost to the surroundings. Specific heat of aluminium = 0.91 J g¯¹ K¯¹