Thermodynamics Question 2
Question 2 - 25 January - Shift 1
An athlete is given $100 g$ of glucose $(C_6 H _{12} O_6)$ for energy. This is equivalent to $1800 kJ$ of energy.
The $50 \%$ of this energy gained is utilized by the athlete for sports activities at the event. In order to avoid storage of energy, the weight of extra water he would need to perspire is____________ g (Nearest integer)
Assume that there is no other way of consuming stored energy.
Given : The enthalpy of evaporation of water is 45 $kJ mol^{-1}$
Molar mass of $C, H \& O$ are 12.1 and $16 g mol^{-1}$.
Show Answer
Answer: (360)
Solution:
Formula: Spontaneous and Non-Spontaneous Process
$C_6 H _{12} O_6(s)+6 O_2 \to 6 CO_2(g)+6 H_2 O(l)$
Extra energy used to convert $H_2 O(1)$ into $H_2 O(1)$
into $H_2 O(g)$
$=\frac{1800}{2}=900 kJ$
$\Rightarrow$ math $900=n _{H_2 O} \times 45$
$ \begin{aligned} & n _{H_2 O}=\frac{900}{45}=20 \text{ mole } \\ & W _{H_2 O}=20 \times 18=360 g \end{aligned} $
