a chemistry question for you to help me with?

L

Linda

New member
Suppose that the microwave radiation has a wavelength of 12 cm. How many photons are required to heat 265 mL of coffee from 25.0 C to 62.0 C? Assume that the coffee has the same density, 0.997 g/mL, and specific heat capacity, 4.184 J/g*K, as water over this temperature range
 
First find how much energy is required:
q = (62.0C-25.0C)(.997g/mL)(265mL)(4.184J/g*K)
q = 40900 J

Then find how much energy is in one mole of photons:
E = Nhc/w
where N is Avogadro's number, h is Planck's constant, c is speed of light, and w is wavelength

E= (6.022*10^23 1/mole)(6.63*10^-34 J*s)(3.00*10^8 m/s)/(12*10^-2m)
E= 1.0 J/mole

Total photons needed = 40900 J/(1.0 J/mole) = 40900 mole

might want to double check calculations
 
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