It should be for the total solution of 93 plus 20 grams which is 113 grams so 93 divided by 113 grams comes to 82.3% sodium sulfate and this can be checked by multiplying 113 grams by 0.823 which results in 93 grams of sodium sulphate.
Answer:
The total energy of the photons detected in one hour is 7.04*10⁻¹¹ J
Explanation:
The energy carried by electromagnetic radiation is displaced by waves. This energy is not continuous, but is transmitted grouped into small "quanta" of energy called photons. The energy (E) carried by electromagnetic radiation can be measured in Joules (J). Frequency (ν or f) is the number of times a wave oscillates in one second and is measured in cycles / second or hertz (Hz). The frequency is directly proportional to the energy carried by a radiation, according to the equation: E = h.f, (where h is the Planck constant = 6.63 · 10⁻³⁴ J / s).
Wavelength is the minimum distance between two successive points on the wave that are in the same state of vibration. it is expressed in units of length (m). In light and other electromagnetic waves that propagate at the speed of light (c), the frequency would be equal to the speed of light (≈ 3 × 10⁸ m / s) between the wavelength :

So:

In this case, the wavelength is 3.35mm=3.35*10⁻³m and the energy per photon is:

E=5.93*10⁻²³ 
The detector is capturing 3.3*10⁸ photons per second. So, in 1 hour:

E=7.04*10⁻¹¹ 
The total energy of the photons detected in one hour is 7.04*10⁻¹¹ J