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If the temperature of 100.0 mL of water rises from 25.0 degree C to 32.0 degree

ID: 905664 • Letter: I

Question

If the temperature of 100.0 mL of water rises from 25.0 degree C to 32.0 degree C, how much heat was added? Assume the density of water is 1.00 g/ml, and the specific heat capacity of the water is 4.184 J/g degree C. Include units and use the correct number of significant figures. S. Define the terms exothermic' and 'endothermic. What is the sign of delta H associated with these two term? Exothermic' Endothermic: Label the following processes as exothermic or endothermic. When CaCI2; dissolves in water, the temperature of the water When NH4NO3 dissolves in water, the temperature of the water decreases.

Explanation / Answer

Q. 4).

Given volume of water = 100.0 mL

Delta T = Tf-Ti = 32.0-25.0 = 7.0 deg C

Solution:

q = m x C x delta T

C is specific heat of water = 4.184 J/ g degC

m is mass of water = 100.0 mL x 1.g / mL

= 100.0 g

Delta T = 7.0 deg C

q = 100.0 g x 4.184 J/g deg C x 7.0 deg C

= 2928.8 J

Heat absorbed by water = 2928.8 J

Exothermic reaction:

The reaction in which is heat is evolved is called as exothermic reaction.

Endothermic :

The reaction in which heat is absorbed is called as endothermic reaction.

a).

H2O (g) --- > H2O (l)

When gas is cooled then then is it is converted to liquid.

This is exothermic reaction since it gives out heat to convert liquid from gas.

b).

H2O (l) --- > H2O (g)

We need to supply heat in order to convert liquid to gas so this is endothermic reaction.

c).

Dissolution of salt (CaCl2) increase temperature of water that means it gives heat to the surrounding water and so it is exothermic reaction.

d)

When NH4NO3 dissolved , temperature of water is lowered. This means that the heat is taken by the reaction.

And so endothermic reaction.

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