Calculating Mass in a Calorimetry Problem

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Discussion Overview

The discussion revolves around a calorimetry problem involving the calculation of the mass of nickel metal based on its heat transfer to water in a calorimeter. Participants explore the application of thermochemical principles and equations to solve the problem, while addressing uncertainties in the calculations and assumptions made.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents a calculation for the mass of nickel using the equation -qnickel=+qwater, expressing uncertainty about the result being too high compared to previous lab experiences.
  • Another participant confirms the reasoning is correct but suggests verifying constants and checking for arithmetic errors, while also questioning the source of the original participant's doubt.
  • A third participant reiterates the importance of the heat capacity of the calorimeter, indicating that it may have been overlooked in the calculations.

Areas of Agreement / Disagreement

Participants generally agree on the correctness of the reasoning applied in the calculations, but there is disagreement regarding the inclusion of the calorimeter's heat capacity, which some believe affects the accuracy of the result.

Contextual Notes

Participants note potential limitations in the constants used for specific heats and the need to consider the calorimeter's heat capacity, which may not have been included in the initial calculations.

Branflake
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Homework Statement



What is the mass of a piece of nickel metal if it is heated to 100.0°C and placed into 250.0 grams of water at 21.52°C in a calorimeter with a heat capacity of 95.3J/K and the temperature stabilizes at 25.82°C?

Homework Equations


-qnickel=+qwater

The Attempt at a Solution


Well this problem is on our review for thermochemistry, but non of the examples we have done or seen (even in the book) really go this far. Here is my first attempt.
-(cnickel X massnickel XΔTnickel)=cwater X masswater X ΔTwater
Plugging in the knowns I get :
Mass of nickel=(4.184J/g*K X 250.0g X 4.3K)/(0.444J/g*K X 74.18K)=136.6g of nickel
I got the specific heat for water through memorization and the specific heat for nickel through a periodic table. Was able to solve it, but for some reason it doesn't feel right. Can't find an example of something similar anywhere.
Am I on the right track at least?
 
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Where does your feeling come from? Can you pin it down?
Does the figure feel too high or too low?

Your reasoning is correct, heat lost by sample is gained by the water.
The calculation followed that. So the places you could make a mistake are in the constants (did you try verifying them?) or an arithmetic error or something like that.

Examples of this problem are easy to come by online.
Did you try looking?
http://www.chemteam.info/Thermochem/MixingMetal&Water.html
 
Simon Bridge said:
Where does your feeling come from? Can you pin it down?
Does the figure feel too high or too low?

Your reasoning is correct, heat lost by sample is gained by the water.
The calculation followed that. So the places you could make a mistake are in the constants (did you try verifying them?) or an arithmetic error or something like that.

Examples of this problem are easy to come by online.
Did you try looking?
http://www.chemteam.info/Thermochem/MixingMetal&Water.html

Thanks this makes me feel a little better about it. Honestly the main reason why I doubted myself is because in the lab we made similar calculations for finding everything but the mass of the metal, but the mass was always between 20g and 70g so my higher value made me concerned.

Also I found that same webpage earlier today, but only the first two problems would load. Thanks for posting it.
 
In general you are on the right track, but seems to me like you ignored heat capacity of the calorimeter.
 

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