Microwave ovens work by irradiating food with microwaves, which are absorbed by the water molecules in the food and converted to heat. Assuming that microwave ovens emit radiation with a wavelength of 29.7 cm, calculate how many photons are emitted per second in a 600-Watt microwave oven. (1 W = 1 J/s)

8.969×10²⁶ photons

Explanation:

From the question,

Using,

E = hc/λ Equation 1

Where E = Energy of the photon, h = Planck's constant, c = speed of light, λ = wave length of the photon.

Given: h =  6.626×10⁻³⁴ J.s, c = 3×10⁸ m/s, λ = 0.297 m

Substitute into equation 1

E = 6.626×10⁻³⁴(3×10⁸)/0.297

E = 6.69×10⁻²⁵ J.

The energy of the photon in one seconds = 6.69×10⁻²⁵ J/s

If the power of the microwave oven  = 600 J/s

Then,

Number of photons emitted per seconds = 600/(6.69×10⁻²⁵)

Number of photons emitted per seconds = 8.969×10²⁶ photons

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.