Posted by Dolapo on Monday, November 8, 2010 at 9:37pm.
Suppose that the microwave radiation has a wavelength of 10.8 cm. How many photons are required to heat 215 mL of coffee from 25.0 ^\circ \rm C to 62.0 ^\circ \rm C? Assume that the coffee has the same density, 0.997 g/mL, and specific heat capacity, 4.184 \rm J/(g\cdot K), as water over this temperature range.

chemistry  DrBob222, Monday, November 8, 2010 at 10:03pm
ASSUMING that ^\circ \rm C to be degrees C, then,
E of one photon = hc/wavelength with wavelength in m.
Energy needed to heat the water is
mass H2O x specific heat H2O x (TfinalTinitial).
Set up a ratio and proportion to calculate the number of photons needed. Post your work if you get stuck and please don't use symbols without identifying them. 
chemistry  kim, Tuesday, November 16, 2010 at 9:48pm
what is the molarity of the solution if 0.135 g sodium sulfate in total volume of 175mL?