contestada

What minimum heat is needed to bring 250 g of water at 20 ∘C to the boiling point and completely boil it away? The specific heat of water is 4190 J/(kg⋅K) and its heat of vaporization is 22.6×105 J/kg.

Respuesta :

Answer:633.8 KJ

Explanation:

Given

mass of water[tex]\left ( m\right )=250gm[/tex]

Initial temperature[tex]\left ( T_i\right )=20^{\circ}C[/tex]

Final temperature [tex]\left ( T_f\right )=100^{\circ}C[/tex]

Specific heat of water [tex]\left ( c \right )[/tex]=4190 J/kg-k

heat of vaporization[tex]\left ( L\right )=22.6\times 10^5 J/kg[/tex]

Heat required for process[tex]\left ( Q\right )[/tex]=heat to raise water temperature from 20 to 100 +Heat to vapourize water completely

Q=mc[tex]\left ( T_f-T_i\right )+mL[/tex]

Q=[tex]0.25\times 4190\times \left ( 100-20\right )+0.25\times 22\times 10^5[/tex]

Q=[tex]\left ( 0.838+5.5\right )\times 10^5[/tex]

Q=[tex]6.338\times 10^5J=633.8 KJ[/tex]