1 / 8

Calculations in Chapter 10

Calculations in Chapter 10. Molar Enthalpy of Fusion. Used when melting or freezing = ___ energy ____ mol of substance Can be arranged to find any of the three Units for molar enthalpy of fusion will be kJ/mol and units for energy is kJ or J, (kilojoules or joules).

ssearcy
Download Presentation

Calculations in Chapter 10

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Calculations in Chapter 10

  2. Molar Enthalpy of Fusion • Used when melting or freezing • = ___energy ____ mol of substance • Can be arranged to find any of the three • Units for molar enthalpy of fusion will be kJ/mol and units for energy is kJ or J, (kilojoules or joules)

  3. Example Problem • The molar heat of fusion for water is 6.009 kJ/mol. How much energy is needed to convert 60.0 g of ice at 0°C to liquid water at 0°C? • Rearrange the formula for energy • Energy =  mol of substance

  4. Have to convert the 60.0 g of ice to mol • Divide by the molar mass of water • 60.0 g/ 18.016 g/mol = • 3.330373002 mol H2O(s) • Energy = 6.009 kJ/mol 3.330373002 mol H2O(s) = • 20.01221137 kJ • 20.0 kJ needed to convert 60.0 g of ice at 0°C to liquid water at 0°C

  5. Molar Enthalpy of Vaporization • Used when boiling or condensing • = energy mol of substance • Can be arranged to find any of the three • Boiling has energy required, condensing gives off energy

  6. Example Problem • How much heat is evolved when 275 g of ammonia gas condenses to a liquid at its boiling point? The molar enthalpy of vaporization for ammonia is 23.3 kJ/mol • Have to convert the g of ammonia to mol of ammonia • 275 g/ 17.034 g/mol = 16.14418222mol

  7. Rearrange the formula for energy evolved • Energy =  mol of substance • Energy = 23.3 kj/mol 16.14418222mol • Energy = 376.1594458 kJ • Energy = 376 kJ

  8. Another Problem • What mass of steam is required to release 4.97 x 105 kJ of heat energy on condensation? The molar enthalpy of vaporization for water is 40.79 kJ/mol • First rearrange to solve for mol • Solve for mol • Multiply by the molar mass to find grams • Answer: 2.20 x 105 g H2O

More Related