The energy content of a certain food is to be determined in a bomb calorimeter that contains 3 kg of water by burning a 2-g samp
le of it in the presence of 100 g of air in the reaction chamber. If the water temperature rises by 3.2°C when equilibrium is established, determine the energy content of the food, in kJ/kg, by neglecting the thermal energy stored in the reaction chamber and the energy supplied by the mixer. By calculating the rough estimate of the error involved in neglecting the thermal energy stored in the reaction chamber, do you think it is reasonable to disregard the change in the sensible energy content of the reaction chamber in the analysis? The specific heat of water at room temperature is c = 4.18 kJ/kg·°C. The constant-volume specific heat of air at room temperature is cv = 0.718 kJ/kg·°C.
The food after the reaction gives out heat which increases the temperature of water and air in the reaction chamber . The heat absorbed by water and air gives the estimate of energy content of the food.
Heat absorbed by water = mass x specific heat x rise in temperature
= 3 x 4.18 x 10³ x 3.2
= 40.128 x 10³ J
Heat absorbed by air = mass x specific heat x rise in temperature
Gravitational field exists in
the space surrounding a charged particle and exerts a force on other charged
particles. Gravitational waves are ripples of waves travelling outward from the
source. The more massive the orbit of two bodies, the more it emits
gravitational wave. And everything around it that is near within the wave
experiences a ‘pull’ toward the orbiting bodies.
