A 2kg block of ice is heated from -200C to 1300C. How much heat is needed to con

Question

A 2kg block of ice is heated from -200C to 1300C. How much heat is needed to convert the block of ice to steam at 1300C? (Hint, the latent heat of fusion and the latent heat vaporization for water are 334,000 J/kg and 2,260,000 J/kg respectively.) In addition to showing all the equations used and work please discuss the following: a) Why is the latent heat of vaporization much greater than the latent heat of fusion. b) Why does the temperature remain constant during phase changes?

Please create a post of at least 100 words.
(I just want to have an second opinion, Im unsure about my answer)

Explanation / Answer

heat needed = raise temp from -200 to 0 + melt + raise temp 0 to 100 + heat to vaporize + raise temp 100 to 1300 =

= mcdeltaT + mL + mcdeltaT + mL + mcdeltaT =

= 2*2090*200 + 2*334000 + 2*4186*100 + 2*2260000 + 2*2010*1200 =

= 3.784 x 10^12 Joules

a) Latent heat of vap is greater because the bonds that must be broken to allow molecules to become gas are much stronger than the bonds that keep molecules in solid form. Stronger bonds require more energy to break, so latent heat of vap (i.e. the heat required to break those bonds) is greater.

b) Temperature remains constant because temperature is related to kinetic energy. Latent heat is related to potential energy, since the energy absorbed by the substance is used to break the bonds associated with the phase change. In contrast, an increase of temperature is associated with an increase in molecular motion. So: temperature change is related to kinetic energy, phase change is related to potential energy.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.