What is the net amount of heat this person could radiate per second into a room at 18.0 ∘C (about 64.4 ∘F) if his skin's surface temperature is 30.0 ∘C? (At such temperatures, nearly all the heat is infrared radiation, for which the body's emissivity is 1.0, regardless of the amount of pigment.)

142.6 joules is the amount of heat that a person could radiate per second

Explanation:

To solve this, we have to apply Stephan-Boltzmann's law:

Q/ΔT = σ . ε . A . (Te⁴ - Ta⁴) where

σ = Boltzmann's constant → 5.67×10⁻⁸ W/m² . K⁴

ε = Body's emissivity, in this case = 1

Α = Surface, we assume a value of 2m²

Te = Temperature of the body's surface, in this case 30°C

Ta = Temperature of the room, where the body is. In this case, 18°C

Notice that T° must be Absolute T° → T°C + 273

18°C + 273 = 291K

30°C + 273 = 303K . Let's replace data:

Q/s = 5.67×10⁻⁸ W/m² . K⁴ . 1 . 2m² (303⁴K - 291⁴K)

Q/s = 5.67×10⁻⁸ W/m² . K⁴ . 1 . 2m² . 1.26×10⁻⁹K⁴

Q/s = 142.6 W

1 W  = Joules/s

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation:

answer : (a) volume of the gas = 8.67 ×   l

                (b) second virial coefficient b = -1.21226 l/mole

solution :   given,     t = 300k

                                p = 20atm

                                z = 0.86

                                n = 8.2 mmoles = 8.2 × moles

                                r =   0.082 l atm/k/mol

        find,     (a) volume of gas   and (b) second virial coefficient b at 300k.

formula used :            

                          and            

(a)            

                    = \times 0.082\times 300}{20}[/tex]

                    = 8.67 ×   l

(b)      

                    = (0.00867-1) × 8.659

                    = - 8.5839 l/mole