A piece of ice (heat capacity #= 2100J kg^(-1 @)C ^-1# and latent heat #= 3.36 xx 10^5 J kg^-1#) of mass #m# gram is at #-5^@C# at atmospheric pressure. It isgiven #420 J# of heat so that the ice starts melting. Finally when the ..........?

Question

A piece of ice (heat capacity #= 2100J kg^(-1 @)C ^-1# and latent heat #= 3.36 xx 10^5 J kg^-1#) of mass #m# gram is at #-5^@C# at atmospheric pressure. It isgiven #420 J# of heat so that the ice starts melting. Finally when the ice-water mixture is in equilibrium, it is found that #1 g# of ice has melted. Assuming there is no other exchange in the process, the value of #m# is?

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Answer 1 · 2018-05-04T17:31:06

Refer to Explanation

Thermal energy absorbed to heat up the ice to #0^@C#:
#Q=m c Delta theta#
#Q=m/1000 * 2100 * [0-(-5)]#
#Q=(10.5m )J#

Thermal energy absorbed to melt 1g of ice:
#Q=ml_v#
#Q=1/1000 * 3.36xx10^5#
#Q=336J#

#(10.5m)J +336J = 420J#
#:.m=8 g#