Find the relative mass of the blocks (thermochemistry)

In summary, the problem asks for the relative masses of two blocks of copper and aluminum after they come into contact with each other, given their specific heat capacities and final temperature. The term "relative masses" refers to the ratio of the two masses. By setting up a heat balance equation and solving for this ratio, the relative masses can be determined.
  • #1
Ritzycat
171
4

Homework Statement


A block of copper at 100.0° C comes into contact with a block of aluminum at 20.0°C. The final temperature of the blocks is 60.0°C. What are the relative masses of the blocks?


Homework Equations


mcΔT
copper specific heat = .386 J/g°C
aluminum specific heat = .900 J/g°C

The Attempt at a Solution



(x)(.386 J/g°C)(40°C) = (x)(.900 J/g°C)(-40°C)
what I use to try to find the mass, assuming that the energy lost in one part of the system is gained by the other... Also, what is meant by "relative" mass in this question?

Until I realize this equation cannot be solved...

Any help is appreciated not really sure how to go about doing this problem, I feel like I am missing something because this should be very easy.
 
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  • #2
Hi Ritzycat! :smile:
Ritzycat said:
… What are the relative masses of the blocks?
… what is meant by "relative" mass in this question?

I think they mean: what is the ratio of the two masses (ie what is one mass relative to the other).

(imo, this is not a correct use of the words "relative masses" :redface:)
 
  • #3
Thanks for the response.

If the question is referring to ratio, wouldn't the ratio of their masses simply be the ratio of the specific heat capacities? (given the absolute value of delta T is the same)
 
  • #4
What can you say about the heat loss/gain of each block?
 
  • #5
Ritzycat said:
If the question is referring to ratio, wouldn't the ratio of their masses simply be the ratio of the specific heat capacities? (given the absolute value of delta T is the same)

Only if you can prove it. Just write heat balance using [itex]m_{Al}[/itex] and [itex]m_{Cu}[/itex] and solve for [itex]\frac {m_{Al}} {m_{Cu}}[/itex].
 

FAQ: Find the relative mass of the blocks (thermochemistry)

1. What is the purpose of finding the relative mass of the blocks in thermochemistry?

The relative mass of the blocks in thermochemistry is used to determine the amount of heat energy required to raise the temperature of a substance. This is an important factor in understanding the thermodynamic properties of a substance and its behavior in various chemical reactions.

2. How is the relative mass of the blocks determined?

The relative mass of the blocks can be determined by first measuring the mass of the block and then calculating the ratio of its mass to the mass of a standard substance, such as water. This ratio is used to determine the specific heat capacity of the substance, which is then used to calculate the relative mass.

3. What is the significance of the relative mass in thermochemistry?

The relative mass of a substance is an important factor in determining its specific heat capacity. This value is used in various thermochemical calculations and is crucial in understanding the energy transfer and chemical reactions of a substance.

4. How does the relative mass affect the energy required to raise the temperature of a substance?

The higher the relative mass of a substance, the more energy is required to raise its temperature. This is because substances with higher relative mass have more particles, which require more energy to increase their kinetic energy and raise the temperature of the substance.

5. Can the relative mass of a substance change?

The relative mass of a substance remains constant, as it is a physical property of the substance. However, in some cases, the relative mass may appear to change due to changes in the chemical composition or structure of the substance, such as in chemical reactions or phase changes.

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