Thermochemistry and Equilibrium of Reaction

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SUMMARY

The discussion focuses on calculating the thermal equilibrium temperature when an ice cube of mass 36 g at -10°C is placed in 360 g of water at 20°C. The key equation for this problem is mc∆T = -mc∆T, where ∆T represents the change in temperature. The heat gained by the water must equal the heat lost by the ice, and the enthalpy of fusion (ΔH = 6.007 kJ/mol) must be considered for the melting of ice. Participants emphasized the importance of accounting for all heat exchanges to accurately determine the equilibrium temperature.

PREREQUISITES
  • Understanding of thermochemistry principles, specifically heat transfer.
  • Familiarity with the concept of molar heat capacity for ice and water.
  • Knowledge of the enthalpy of fusion and its application in phase changes.
  • Ability to manipulate equations involving mass, specific heat, and temperature changes.
NEXT STEPS
  • Study the derivation and application of the equation mc∆T = -mc∆T in thermal equilibrium problems.
  • Learn about the concept of enthalpy of fusion and its role in phase change calculations.
  • Explore the principles of heat transfer in closed systems with varying masses and temperatures.
  • Practice similar thermochemistry problems involving phase changes and thermal equilibrium.
USEFUL FOR

Students studying thermochemistry, educators teaching heat transfer concepts, and anyone interested in understanding thermal equilibrium calculations in physical chemistry.

highcoughdrop
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Homework Statement


An ice cube of mass 36 g at temperature -10 Celsius is placed in 360 g of water at 20 Celsius. Find thermal equilibrium temperature. \DeltaH(fusion) = 6.007 kJ mol\wedge-1.

Molar heat capacity of ice = 38
water = 75 (Joules)/(K mol)

Assume no heat loss to the surroundings.

Homework Equations


\Delta H = n(Cp) \DeltaT

q = M (Cs) delta T




The Attempt at a Solution


I tried to find the thermal temperature first by using the temperature above, but I got different temperatures that were not even close to what they should be. THe thermal temperatures should be between -10 and 20, however they are going to be closer to the 20 because water mass is much more than mass of ice.
 
Last edited:
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Hello there,

You are missing a key equation:

mc∆T = -mc∆T,

where ∆T = Tf - Ti.

I encourage you to learn this equation and then retry the problem. If you need any more help, please write back!
 
vertciel said:
mc∆T = -mc∆T,

where ∆T = Tf - Ti

First - it is a very particular case.

Second - it doesn't account for the ice melting.

highcoughdrop: heat gained = heat lost; can you list all partial heats thet wll be lost/gained before ysstem will get to the equilibrium?
 

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