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April 20, 2014

# Homework Help: chemistry

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 (Tfinal-Tinitial).
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?

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