Microwave light is used to melt a 2.0 kg block ofice at 0 degrees into water (21H2168O) at 0 degrees. Use Lf = 3.35x 105 J/kg for ice at the normal melting point. a) Find the number of photons (=2,000 nm) to melt theice. b) On average, how many H2O molecules does onephoton convert from ice phase to liquid water phase? Microwave light is used to melt a 2.0 kg block ofice at 0 degrees into water (21H2168O) at 0 degrees. Use Lf = 3.35x 105 J/kg for ice at the normal melting point. a) Find the number of photons (=2,000 nm) to melt theice. b) On average, how many H2O molecules does onephoton convert from ice phase to liquid water phase? a) Find the number of photons (=2,000 nm) to melt theice. b) On average, how many H2O molecules does onephoton convert from ice phase to liquid water phase?
Explanation / Answer
The amount of energy required to 2.0 kg block of ice isconverted into liquid water is Q= mLf = (2.0 kg)( 3.35 x 105 J/kg ) =6.7x 105J/kg a) The number of photons are N= Q/((hc)/) = (6.7x 105J/kg)/((6.63*10-34J.s)(3*108m/s)/(2000*10-9m)) = 6.737*1024 b) The massof H2O molecules is m= 3.006*10-26kg The number ofwater molecules are n=mLf/((hc)/) Substitute thevalues for n. The number ofwater molecules are n=mLf/((hc)/) Substitute thevalues for n.