Q. 34.2( 42 Votes )

# What is meant by specific heat capacity? How will you prove experimentally that different substances have different specific heat capacities?

Answer :

The amount of heat energy required to raise the temperature of a unit mass of an object by 1^{°} C is called the specific heat capacity of that object.

__To prove experimentally:__

(i) Take three spheres of iron, copper and lead of equal masses.

(ii) Now put all the three spheres in boiling water in the beaker for some time.

(iii) Now, take them all out of the water, we will notice that all the spheres will be at temperature 100^{°} C.

(iv) Now, put them immediately on the thick slab of wax.

(v) Note the depth of each sphere into the wax.

(vi) The sphere which has absorbed more heat from water will give more heat to wax.

(vii) More wax will thus melt, and deeper the sphere will go in the wax.

(viii) We will notice, iron goes deepest, lead sphere goes the least and copper sphere goes to intermediate depth.

(ix) This shows that for equal rise in temperature, the three spheres have absorbed different amounts of heat.

(x) This means that the property which determines the amount of heat absorbed by a sphere is different for the three spheres.

(xi) This property is called the specific heat capacity.

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Solve the following problems:

Liquid ammonia is used in an ice factory for making ice from water. If the water at 20^{o}C is to be converted into 2 kg ice at 0^{o}C, how many grams of ammonia is to be evaporated?

(Given: The latent heat of vaporization of ammonia= 341 cal/g)

MHB - Science and Technology Part-1Solve the following problems:

Equal heat is given to two objects A and B of mass 1 g. Temperature of A increases by 3^{o}C and B by 5^{o}C. Which object has more specific heat? And by what factor?

Solve the following problems:

A calorimeter has mass 100 g and specific heat 0.1 kcal/ kg°C. It contains 250 gm of liquid at 30°C having a specific heat of 0.4 kcal/kg°C. If we drop a piece of ice of mass 10g at 0°C, What will be the temperature of the mixture?

MHB - Science and Technology Part-1