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Thermodynamic Question Help


Hello everyone, I need some help for the problems listed below. Would really appreciate it.

Microwave photons are used everyday to heat our foods, by increasing the kinetic energy
of the molecules! Suppose you have 325. mL of soup that you want to eat for a quick lunch. You
want to heat the soup from 15.5 to 85.0°C in a microwave that uses photons with a wavelength of
18.2 cm.

a) If the soup has a specific heat equal to that of water but a density of 1.22 g/mL, how many moles
of photons must be absorbed to heat the soup, assuming that all the energy of the photons can be
transferred completely to only the soup?
b) Microwave power is usually rated in terms of Watts, which are joules of energy transferred per
second (1 Watt = 1 Joule/s) from the energy source. If you used an 800-Watt microwave to heat the
soup in this question, how many minutes would the microwave oven need to produce enough photons to heat your soup?

Where have you got stuck? For instance, how much energy do you need to heat the food up?


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