How much heat is released from water into ice.

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Homework Help Overview

The discussion revolves around calculating the heat released when water freezes and subsequently cools to a lower temperature. The subject area includes thermodynamics and phase changes, specifically focusing on the heat transfer involved in the freezing of water and the cooling of ice.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the problem in stages: cooling to the freezing point, freezing, and cooling to the final temperature. There are attempts to apply the appropriate heat constants for each stage, and questions arise regarding the calculations and the signs of the heat values.

Discussion Status

Some participants have identified mistakes in their calculations and expressed a sense of resolution. However, there remains a lack of explicit consensus on the correct approach, as different methods and interpretations are being explored.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may impose specific requirements for the calculations and the presentation of results. There is also a focus on ensuring the correct application of heat constants for each phase of the process.

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Homework Statement


How much heat is released when 250 g of water at 10 degrees celsius freezes into ice and cools to -10 degrees celsius?

Homework Equations


Q=mcΔt

The Attempt at a Solution



q= (250g)(4186)(283-273)=1.046*10^4 J

than q=(250g)(2090)(263-283)=-1.045*10^4 J

when i subtract the two i get 1*10^4

The answer is -9.86*10^4 what am i doing wrong?
 
Last edited:
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Three stages:
1. Cool to freezing point
2. Freeze
3. Cool to final temp

Each stage is governed by a different heat constant.
 
OK this is what I'm doing

1. cool to freezing point

q=(.250kg)(4186J/kgK)(273K-283K)=-1.046*10^4J

2.Freeze

MLf=(.250)(3.33*10^5)=8.32*10^4 J

3.Cool to final temp

Q= (.250kg)(2090j/kgK)(-283K-273K)=-2.90510*10^5

so when i sum up Q1+mLf+Q2= -2.177*10^5 J
Like seriously what am i doing wrong?
 
got it! i found the mistakes ! thanks! :D
 

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