List of Factors Affecting Quantity of Heat Absorbed, Melting and Boiling Point etc.

Frequently Tested Topics:

  • Heat capacity - definition, S.I unit

  • Principle of Calorimetry 

  • Numericals based on principle of calorimetry

  • Numericals based on heat capacity, latent heat

  • Give reasons based on high specific heat capacity of water

  • Relation and difference between heat capacity and specific heat capacity

  • Latent heat - definition, concept, numericals

  • Factors affecting heat absorbed by a body

  • Factors affecting melting and boiling points

  • Material used in a calorimeter, reason for usage, prevention of heat loss

  • Temperature-time graphs

*Note that other aspects of the chapter are equally important.

Important Past Questions:

  • Define the term 'heat capacity' and state its S.I unit.

(2008, 2013, 2017)

  • Name the physical quantity which is measured in calories. How is calorie related to the S.I unit of that quantity?

(2019)

  • The specific heat capacity of a substance A is 3,800 J kg⁻¹ K⁻¹ and that of substance B is 400 J kg⁻¹ K⁻¹. Which of the two substances is a good conductor of heat? Give reason.

(2014, 2019)

  • State whether the specific heat capacity of a substance remains the same when its state changes from solid to liquid. Give an example to support your answer.

(2019)

  • How can temperature in degree Celsius be converted into S.I unit of temperature?

(2018)

  • A liquid X has the maximum specific heat capacity and is used as a coolant in car radiators. Name the liquid X.

(2010, 2018)

  • A solid metal weighing 150g melts at its melting point of 800°C by providing heat at the rate of 100W.  The time taken for it to completely melt at the same temperature is 4 min. What is the specific latent heat of fusion of the metal?

(2018)

  • Why is the base of a cooking pan generally made thick?

(2017)

  • A solid of mass 50g at 150°C is placed in 100g of water at 11°C, when the final temperature recorded is 20°C. Find the specific heat capacity of the solid. Specific heat capacity of water = 4.2 J g⁻¹°C⁻¹

(2017)

  • Calculate the mass of ice required to lower the temperature of 300g of water at 40°C to water at 0°C. Specific latent heat of ice = 336J/g. Specific heat capacity of water = 4.2 J g⁻¹°C⁻¹

(2016)

  • What do you understand by the following statements:

i) the heat capacity of the body is 60J K⁻¹.

ii) the specific heat capacity of lead is 130 J kg⁻¹ K⁻¹.

(2009, 2016)

  • State two factors on which the heat absorbed by a body depends.

(2010, 2016, 2017)

  • Rishi is surprised when he sees water boiling at 115°C in a container. Give reasons as to why water can boil at the above temperature.

(2015)

  • Which property of water makes it an effective coolant?

(2015)

  • 50g of metal piece at 27°C requires 2400J of heat energy so as to attain a temperature of 327°C. Calculate the specific heat capacity of the metal.

(2014)

  • How much heat energy is released when 5g of water at 20°C changes to ice at 0°C? Specific latent heat of fusion of ice = 336J/g. Specific heat capacity of water = 4.2 J g⁻¹ °C⁻¹

(2006, 2013)

  • Differentiate between

i) heat capacity and specific heat capacity. (2012, 2018)

ii) heat and temperature. (2011)

  • A hot solid of mass 60g at 100°C is placed in 150g of water at 20°C. The final steady temperature recorded is 25°C. Calculate the specific heat capacity of the solid. Specific heat capacity of water = 4200 J kg⁻¹ °C⁻¹

(2012)

  • 200g of hot water at 80°C is added to 300g of cold water at 10°C. Calculate the final temperature of the mixture of water. Consider the heat taken by the container to be negligible. Specific heat capacity of water = 4200 J kg⁻¹ °C⁻¹

(2011)

  • Which material is the calorimeter commonly made of? Give one reason for using this material.

(2006, 2010, 2019)

  • Why do pieces of ice added to a drink cool it much faster than ice cold water added to it?

(2009, 2013)

  • 40g of water at 60°C is poured into a vessel containing 50g of water at 20°C. The final temperature recorded is 30°C. Calculate the thermal capacity of the vessel. Specific heat capacity of water = 4.2 J g⁻¹ °C⁻¹.

(2009)​

  • Some hot water was added to three times its mass of cold water at 10°C and the resulting temperature was found to be 20°C. What was the temperature of the hot water?

(2007)

  • Define calorimetry.

(2019)

  • The melting point of naphthalene is 80°C and the room temperature is 30°C. A sample of liquid naphthalene at 100°C is cooled down to the room temperature. Draw a temperature-time graph to represent this cooling. In the graph, mark the region which corresponds to the freezing process.

(2019)

  • i) Heat supplied to a solid changes it into liquid. What is this change in phase called?

ii) During the phase change does the average kinetic energy of the molecules of the substance increase?

iii) What is the energy absorbed during the phase change called?

(2018)

  • Give a mathematical relation between heat capacity and specific heat capacity.

(2009, 2013, 2018)

  • How is transfer of heat energy by radiation prevented in a calorimeter?

(2017)

  • You have a choice of three metals A, B and C of specific heat capacities 900 J kg⁻¹ °C⁻¹, 380 J kg⁻¹ °C⁻¹, and 460 J kg⁻¹ °C⁻¹ respectively, to make a calorimeter. Which material will you select? Justify your answer.

(2017)

  • Calculate the mass of ice needed to cool 150g of water contained in a calorimeter of mass 50g at 32°C such that the final temperature is 5°C. Specific heat capacity of calorimeter = 0.4 J g⁻¹ °C⁻¹. Specific heat capacity of water = 4.2 J g⁻¹ °C⁻¹. Latent heat capacity of ice = 330 J/g.

(2017)

  • i) What is the principle of method of mixtures?

ii) What is the other name given to it?

iii) Name the law on which the principle is based.

(2009, 2015, 2016)

  • Some ice is heated at a constant rate, and its temperature is recorded after every few seconds, till steam is formed at 100°C. Draw a temperature-time graph to represent the change. Label the two phase changes in the graph.

(2008, 2012, 2016)

  • It is observes that the temperature of the surroundings starts falling when the ice in a frozen lake starts melting. Give a reason for the observation.

(2013)

  • A certain amount of heat Q will warm 1g of material X by 3°C and 1g of material Y by 4°C. Which material has a higher specific capacity?

(2013)

  • Write an expression for the heat energy liberated by a hot body.

(2012)

  • Some heat is provided to a body to raise its temperature by 25°C. What will be the corresponding rise in temperature of the body as shown on the Kelvin scale?

(2012)

  • What happens to the average kinetic energy of the molecules as ice melts at 0°C?

(2012)

  • Explain why the weather becomes very cold after a hail storm.

(2011)

  • What happens to the heat supplied to a substance when the heat supplied causes no change in the temperature of the substance?

(2011)

  • When 1g of ice at 0°C melts to form 1g of water at 0°C then is the latent heat absorbed by the ice or given out by it?

(2011)

  • Give an example where high specific heat capacity of water is used as a heat reservoir.

(2011)

  • Give an example where high specific heat capacity of water is used for cooling purposes.

(2011)

  • Define 'specific latent heat of fusion' of a substance.

(2006, 2011)

  • ​Explain why water is used in hot water bottles for fomentation and also as a universal coolant.

(2006)

  • 104g of water at 30°C is taken in a calorimeter made of copper of mass 42g. When a certain mass of ice at 0°C is added to it, the final steady temperature of the mixture after the ice has melted was found to be 10°C. Find the mass od ice added. Specific latent heat of ice = 336J/g. Specific heat capacity of water = 4.2 J g⁻¹°C⁻¹. Specific heat capacity of copper = 0.4 J g⁻¹°C⁻¹

(2019)

  • The temperature of 170g of water at 50°C is lowered to 5°C by adding a certain amount of ice to it. Find the mass of ice added. Specific heat capacity of water = 4200 J kg⁻¹ °C⁻¹. Specific latent heat of ice = 336000 J kg⁻¹.

(2018)

  • A copper vessel of mass 100g contains 150g of water at 50°C. How much ice is needed to cool to 5°C? Specific latent heat of ice = 336J/g. Specific heat capacity of water = 4.2 J g⁻¹°C⁻¹. Specific heat capacity of copper = 0.4 J g⁻¹°C⁻¹

(2016)

  • State the effect of an increase of impurities on the melting point of ice.

(2015)

  • Water in lakes and ponds do not freeze at once in cold countries. Give a reason in support of your answer.

(2015)

  • A refrigerator converts 100g of water at 20°C to ice at -10°C in 35 minutes. Calculate the average rate of heat extraction in terms of watts. Specific latent heat of ice = 336J/g. Specific heat capacity of water = 4.2 J g⁻¹°C⁻¹. Specific heat capacity of ice = 2.1 J g⁻¹°C⁻¹.

(2015)

  • Heat energy is supplied at a constant rate to 100g of ice at 0°C. The ice is converted into water at 0°C in 2 minutes. How much time will be required to raise the temperature of water from 0°C to 20°C? Specific latent heat of ice = 336J/g. Specific heat capacity of water = 4.2 J g⁻¹°C⁻¹.

(2014)

  • A calorimeter of mass 50g and specific heat capacity 0.42 J g⁻¹°C⁻¹ contains some mass of water at 20°C. A metal piece of mass 20g at 100°C is dropped into the calorimeter. After stirring, the final temperature is found to be 22°C. Find the mass of water used in the calorimeter. Specific heat capacity of water = 4.2 J g⁻¹°C⁻¹. Specific heat capacity of the metal piece = 0.3 J g⁻¹°C⁻¹.

(2013)

  • 40 g of ice at 0°C is used to bring down the temperature of a certain mass of water at 60°C to 10°C. Find the mass of water used.  Specific heat capacity of water = 4200 J kg⁻¹ °C⁻¹. Specific latent heat of ice = 336 x 10^3 J kg⁻¹.

(2012)

  • 250 g of water at 30°C is present in a copper vessel of mass 50 g. Calculate the mass of ice required to bring down the temperature of the vessel and its contents to 5°C.  Specific heat capacity of water = 4200 J kg⁻¹ °C⁻¹. Specific latent heat of ice = 336000 J kg⁻¹. Specific heat capacity of copper vessel = 400 J kg⁻¹ °C⁻¹.

(2011)

  • 50g of ice at 0°C is added to 300g of a liquid at 30°C. What will be the final temperature of the mixture when all the ice has melted? The specific heat capacity of the liquid is 2.65 Jg⁻¹°C⁻¹ while that of water is 4.2 J g⁻¹°C⁻¹. Specific latent heat of fusion of ice = 336Jg⁻¹.

(2010)

  • Calculate the amount of ice which is required to cool 150g of water contained in a vessel of mass 100g at 30°C, such that the final temperature of the mixture is 5°C. (Take specific heat capacity of material of vessel as 0.4 J g⁻¹°C⁻¹, specific latent heat of fusion of ice = 336 J g⁻¹°, specific heat capacity of water – 4.2J g⁻¹°C⁻¹.) 

(2009)

  • A piece of ice of mass 40g is dropped into 200g of water at 50°C. Calculate the final temperature of water after all the ice has melted.  (specific heat capacity of water = 4200J kg⁻¹°C⁻¹, specific latent heat of fusion of ice = 336 × 10^3 J/kg)

(2008)

  • A piece of iron of mass 2.0 kg has a thermal capacity of 966 J °C⁻¹. 

(i) How much heat energy needed to warm it by 15°C?

(ii) What is its specific heat capacity in S.I. units?

(2006)

DIAGRAM BASED QUESTIONS

A substance is in the form of a solid at 0°C. The amount of heat added to this substance and the temperature of the substance are plotted on the following graph.

 If the specific heat capacity of the solid substance is 500J/kg/°C, find from the graph: 

i) the mass of the substance  

ii) the specific latent heat of fusion of the substance in the liquid state.

(2007)

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