5.4 kcal/g is the caloric value of the french fries.
Explanation:
- The amount of heat generated by the combustion of a unit quantity of the substance is termed as caloric value.
Given :
The mass of a sample of the french fries = 2.5 g
The mass of water in calorimeter = 500.0 g
The initial temperature of the water = 21 °C
The final temperature of the water =48 °C
To find:
The caloric value of the french fries
Solution:
The mass of water in calorimeter = m= 500.0 g
The initial temperature of the water =[tex]T_i=21^oC[/tex]
The final temperature of the water =[tex]T_f=48^oC[/tex]
The specific heat of the water = c =[tex]4.186 J/g^oC[/tex]
The amount of heat absorbed by the water due to combustion of french fries= Q
[tex]Q=m\times c\times (T_f-T_i)\\\\Q=500.0 g\times 4.186 J/g^oC\times (48^oC-21^o)\\[/tex]
[tex]Q=56,511 J\\1 calorie= 4.186 Joules\\Q=56,511 J=56,511\times \frac{1}{4.186 }cal=13,500 cal[/tex]
The amount heat released on combustion of 2.5 grams of french fries = Q'
Q ' = -Q (Law of conservation of energy)
Q'= -13,500 cal
(Negative sign means that heat energy was released)
The mass of a sample of the french fries = M = 2.5 g
The caloric value of the french fries:[tex]=\frac{Q'}{M} =\frac{-13,500 cal}{2.5 g}=5,400 cal/g\\1 cal = 0.001 kcal\\= 5,400 cal/g=5,400\times 0.001 kcal/g=5.4 kcal/g[/tex]
5.4 kcal/g is the caloric value of the french fries.
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