# number of photons absorbed by water?

A container with 0.413 L of water is placed into microwave and is then radiated with electromagnetic energy that has a wavelength of 11.3 cm. The temperature of the water then rose by 69.9 °C. Calculate the number of photons that were absorbed by the water. Assume water has a density of 1.00 g·mL–1 and its specific heat is 4.184 J·g–1·°C–1

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- hcbiochemLv 79 months ago
First, calculate the amount of energy in J that the water must absorb:

q = m c (T2-T1)

q = 413 g (4.184 J/gC) (69.9 C) = 1.21 X 10^5 J

Now, use the equation E = hc/wavelength to calculate the energy of a single photon.

E = 6.626X10^-34 Js (3.00X10^8 m/s) / 0.113 m = 1.76X10^-24 J/photon

Number of photons = 1.21X10^5 J / 1.76X10^-24 J/photon = 6.88X10^28 photons

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