I believe a heterogenous mixture cannot be considered as a single phase.
Answer: longer wavelength and lower energy.
Explanation:
1) The wavelength is inversely related to the frequency. So, an electromagnetic wave with lower frequency will have longer wavelength.
This is the formula for electromagnetic waves:
λ = c / ν
where λ is the wavelength, c is the speed of light, and ν is the frequency.
2) Energy is directly related to the frequency.
This is the formula E = hν,
where E is the energy, h is Planck constant, and ν is the frequency.
So, the lower the frequency the lower the energy.
3) Conclusion:
<span>An electromagnetic wave that has a lower frequency than infrared radiation will have longer wavelength and lower energy than the infrared radiation</span>
The equation for the reaction describe in the question is NH4Cl (s) --> NH3 (g) + HCl (g)
the equation of heat reaction :
ΔH25° = (ΔH25° NH3 + ΔH25° HCl) - (ΔH25° NH4Cl)
use the table from basic chemical engineering calculations of himmelblau or felder to find ΔH25°.ΔH25° of products minus ΔH25° of reactants.
hope this help