Calculating Heat Transfer and Enthalpy Changes in Phase Transitions
This text explores the calculations of heat transfer and enthalpy changes involving specific materials such as lead and water. It includes various scenarios, such as the cooling of lead, heating of water, and phase changes from ice to water and steam. The calculations involve determining the amount of heat released or absorbed using specific heat capacities and enthalpy values. Additionally, it presents a real-life application, where the energy from burning food items is compared to the heat required for heating water to steam.
Calculating Heat Transfer and Enthalpy Changes in Phase Transitions
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Presentation Transcript
The specific heat of lead is 0.129 J/g°C. Find the amount of heat released when 497.28 g of lead are cooled from 37.2°C to 22.5°C.
225.0 J of heat are applied to an 87.0 g sample of water. If the sample’s temperature was initially 18.9 °C , what will it’s final temperature be? The specific heat of water is 4.184J/g °C .
While taking a relaxing bubble bath one evening, Cindy wonders how much heat would be needed to convert a tub full of 50.5 L of water at 46.8 °C to steam at 100.0 °C. She knows that ΔHvap = 40.7kJ/mol for water and that Cwater = 4.184 J/g °C. Can you tell Cindy how much heat would be needed? • Then Cindy began to wonder if she could accomplish this task by burning Honey Buns. According to the nutrition label, each Honey Bun is equal to 650,000 J of energy!! Can you tell Cindy how many Honey Buns she would need to burn to turn the tub water into steam?
Cice= 2.108 J/g°CCwater= 4.186 J/g°CCsteam= 1.996 J/g°C ∆Hfus = 6.02 kJ/mol∆Hvap= 40.7 kJ/mol What is the change in enthalpy when 10.00 g of ice at -15.00°C is converted to liquid water and heated to 25°C? What is the change in enthalpy when 17.50 mL of water at 60.00°C is converted to steam and heated to 112.00°C ?
Cice= 2.108 J/g°CCwater= 4.186 J/g°CCsteam= 1.996 J/g°C ∆Hfus = 6.02 kJ/mol, ∆Hvap = 40.7 kJ/mol 1. What is the change in enthalpy when 32.00 g of ice at -5.00°C is converted to steam and heated to 122.00°C? 2. What is the change in enthalpy when 20.0 g of steam at 107°C is condensed into a liquid and cooled to 35°C? 3. What is the change in enthalpy when 85.0 g of water at 78°C freezes and cools to a solid at -
Cice= 2.108 J/g°CCwater= 4.186 J/g°CCsteam= 1.996 J/g°C∆Hfus = 6.02 kJ/mol, ∆Hvap = 40.7 kJ/mol • What is the change in enthalpy when 15.25g of ice at -25.0°C is heated to liquid water at 19.0°C? • What is the change in enthalpy when 23.4g of steam at 112°C is cooled to a solid at -21°C?
