Calculate the amount of heat in kilojoules required to vaporize 2.58 kg of water at its boiling point.

The amount of heat required to vaporize 2.58 kg of water at its boiling point is 5,830.8 kJ.

Explanation:

A substance undergoes a change in temperature when it absorbs or gives up heat to the environment around it. However, when a substance changes phase it absorbs or gives up heat without causing a change in temperature. The heat Q that is necessary for a mass m of a certain substance to change phase is equal to:

Q = m*L

where L is called the latent heat of the substance.

In this case:

Replacing:

Q= 2.58 kg* 2260*10³ J/kg

Q= 5,830,800 J = 5,830.8 kJ (Being 1,000 J= 1 kJ)

The amount of heat required to vaporize 2.58 kg of water at its boiling point is 5,830.8 kJ.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"