What Is the Correct Mass of Water When Hot Copper Meets Cold Water?

  • Thread starter Thread starter Pengwuino
  • Start date Start date
  • Tags Tags
    Hot Metal Water
AI Thread Summary
The discussion revolves around calculating the mass of water when a hot copper sample is placed in it, using the principle of heat transfer. The user initially applies the heat transfer equation but arrives at an incorrect mass of water, leading to frustration. They suspect issues with significant figures or numerical calculations, as they consistently get a different answer. Another participant suggests that the correct mass should be around 90.59 g, indicating potential errors in the user's calculations. The conversation highlights the common challenges faced in thermodynamics problems and the importance of careful numerical analysis.
Pengwuino
Gold Member
Messages
5,112
Reaction score
20
hot metal + water = Tf?

Yet again I find i am stumped by having no clue as to what I did in this incredibly easy problem.

A 110.-g sample of copper (specific heat capacity = 0.20 J/ºC•g) is heated to 82.4 ºC and then placed in a container of water at 22.3 ºC. The final temperature of the water and copper is 25.6 ºC. What is the mass of the water in the container, assuming that all heat lost by the copper is gained by the water?

Simple right?

1 = water
2 = copper

m1c1 delta T1 = -m2c2 delta T2

This simplifies to...

m1= (-m2c2 delta T2)/(c1 delta T1)

which is...

(-(110*.2*(25.6-82.4)))/((4.18*(25.6-22.3)) = 95.8533g

Computer says I'm wrong and it slapped me

I then did the lazy way and calculated the energy required to lower the copper's temperature. With that, I manually figured out how much water there was and got the exact same answer.

Where am I going wrong here?
 
Last edited:
Physics news on Phys.org
Significant digits? I don't know... :confused:
 
Did you do your numerical calculation right? Isn't the answer 90.59 g?
 
I tried 3 and 4 sig. figures with +/- 1 each direction and nothings coming out correctly. God i want to pound the writers of this textbook.
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »

Similar threads

Change in entropy when mixing cold and hot water
Replies
12
Views
4K
Entropy change for two masses of water mixed adiabatically
Replies
1
Views
2K
Specific Heat Question: Calculating Temperature Change with Copper and Water
Replies
2
Views
1K
Calorimetry: mix of ice, water vapor inside a copper container
Replies
6
Views
2K
Specific heat capacity of calorimeter
Replies
6
Views
3K
What Is the Final Temperature When Ice and Water Mix?
Replies
8
Views
5K
Specific Heat Problem, not getting the correct answer
Replies
5
Views
2K
Solving for Final Equilibrium Temperature of Water-Copper System
Replies
2
Views
1K
What Is the Entropy Change When Ice Melts in Hot Water?
Replies
2
Views
2K
Solving Final Temperature of Copper-Water Mixture
Replies
4
Views
4K

Hot Threads

Recent Insights

Back
Top