m of
emits
and
alue
THERMAL PROPERTIES OF MATTER
41. 50gm of water and an equal volume of alcohol
(sp.gravity = 0.8) are placed one after another
in a calorimeter of water equivalent 2gm. They
are found to cool from 60°C to 55°C in 2 min.
and 1min respectively. The sp.heat of Alcohol
in Cal gm-1 °C -1 is
1) 0.1 2) 0.3 3) 0.4
rate
t=0.697 A
4) 0.6
Answers
Answer:
sorry I didn't understand the question
Explanation:
Question 1: What is heat? What is the S. I. unit of heat?
Answer: Heat is a form of energy, which when absorbed by a body makes it hot and when extracted from a makes it cold. It is also defined as the total kinetic energy possessed by all the molecules of a body. The S. I. unit of heat is joule/kg kelvin.
Question 2: Define the term calorie. How is it related with joule (the SI unit of heat)?
Answer: One calorie is the heat required to raise the temperature of 1 g of water from 14.5°C to 15.5°C
1 Calorie = 4.2 joule.
Question 3: Differentiate between heat and temperature.
Answer:
Heat Temperature
1. It is a form of energy. It is the sensation of hotness and coldness.
2. Unit of heat is Joule. Unit of temperature is °C or Kelvin.
Question 4: What are other units of heat? Name and define them.
Answer: (i) Calorie: It is the quantity of heat required to raise the temperature of 1 gm of water by 1°C (more accurately the rise in temperature is taken from 14.5°C to 15.5°C).
(ii) Kilo calorie: It is the quantity of heat required to raise the temperature of 1 kg of water by 1°C. It is equivalent to 1000 calories.
Question 5: How is the heat capacity of a body related to the specific heat capacity of its substance?
Answer: Heat capacity of a body = Mass of the body × Specific heat capacity of its substance.
Question 6: State the condition for the flow of heat energy from one body to another.
Answer: Heat energy always flows from a body at a higher temperature to a body at a lower temperature.
Question 7: What are the factors on which the quantity of heat given to a body depends?
Answer: The quantity of heat given to body depends on:
(i) The mass of the body, (ii) The rise (or fall) in the temperature of the body, and (iii) Nature of the material of the body.
Question 8: m kg of a substance of specific heat capacity s J/kg °C is heated so that its temperature rises from θ1°C to θ2°C. Write down the expression for the heat Q supplied.
Answer: Heat supplied Q = mass × sp. heat capacity × rise in temperature
= m × s × (θ2 – θ1)
Question 9: Name the substance which has maximum specific heat capacity.
Answer: Water has the maximum specific heat capacity.
Question 10: Write two advantages of high specific heat capacity of water.
Answer: (i) Water is used as an effective coolant in radiator of a car.
(ii) Hot water bottles are used for fomentation.
Question 11: Does the specific heat capacity of a substance depend upon its mass and rise in temperature only?
Answer: No, for the same mass and for the same rise in temperature for different substance, the specific heat capacity is found to be different. Thus, specific heat capacity depends upon the nature of the substance also and so its is different for different substances.
Question 12: Write the approximate values of: (i) the specific latent heat of fusion of ice, (ii) the specific latent heat of vaporisation of steam.
Answer: (i) The specific latent heat of fusion of ice is 3,36,000 J/Kg.
(ii) The specific latent heat of vaporisation of steam is 22,60,000 J/kg.
Question 13: The specific latent heat of fusion of ice is 336 J/g. Comment on this.
Answer: The heat required to convert 1 g of ice from 0°C to 1 g water at 0°C is 336J.
Question 14: The farmers fill their fields with water in winter. Give reason.
Answer: The farmers fill their fields with water in winter to protect the crops from frost because water due to its high specific heat capacity does not allow the temperature in the surrounding area of plants to fall below 0°C.
Question 15: Why is specific heat capacity taken as a measure of thermal inertia?
Answer: We have H = ms Δθ or Δθ = (H/ms).
It follows that if s is more, Δθ will be small (for given values of H and m). Thus, for a given body, its specific heat capacity determines the change in temperature produced by a given quantity of heat. It is thus like mass in mechanics which determines the change in velocity (or the acceleration) produced by a given forc