Specific heat capacity and final temperature

In summary: Yes, you need to calculate with 100-Tf, but I got different result. Do not drop significant digits during the calculations.
  • #1
moimoi24
48
0

Homework Statement



A 2.8 kg sample of a metal with a specific heat of 0.43KJ/KgC is heated to 100.0C then placed in a 50.0 g sample of water at 30.0C.* What is the final temperature of the metal and the water?


Homework Equations



heat loss by the metal = heat gain by the water

The Attempt at a Solution



I solve it this way:
2800 g x 430 J/gC x (Tf-100) = 50 g x 4.2 J/gC x (Tf - 30)

my final answer is 100 C,

please help me check what makes my answer wrong because the answer on the key is 97C...

Thanks a lot...
 
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  • #2
i solve it again and i got 114 as the answer because of 0.43KJ/KgC, it will be 0.43J/gC... Please help me with this one, what makes it wrong?
 
  • #3
moimoi24 said:

Homework Equations



heat loss by the metal = heat gain by the water

The Attempt at a Solution



I solve it this way:
2800 g x 0.430 J/gC x (Tf-100) = 50 g x 4.2 J/gC x (Tf - 30)

Check the red one. Is it really the heat lost by the metal?


ehild
 
  • #4
ehild said:
Check the red one. Is it really the heat lost by the metal?


ehild

is it 2800 g x 0.43J/gC x 70 C?
 
  • #5
You said that the heat lost by the metal is equal to the heat gained by water.
The metal cools down from 100 C° to Tf, how much heat releases in the cooling process?

ehild
 
  • #6
ehild said:
You said that the heat lost by the metal is equal to the heat gained by water.
The metal cools down from 100 C° to Tf, how much heat releases in the cooling process?

ehild
i think it should be100C - tf, since there is a decrease in temperature. my answer is 90C, is that correct?
 
  • #7
moimoi24 said:
i think it should be100C - tf, since there is a decrease in temperature. my answer is 90C, is that correct?

Yes, you need to calculate with 100-Tf, but I got different result. Do not drop significant digits during the calculations.

ehild
 

FAQ: Specific heat capacity and final temperature

1. What is specific heat capacity?

Specific heat capacity is the amount of energy required to raise the temperature of one gram of a substance by one degree Celsius. It is a measure of how well a substance can store and release thermal energy.

2. How is specific heat capacity different from heat capacity?

Heat capacity is the amount of energy required to raise the temperature of an entire object by one degree Celsius. Specific heat capacity is the energy required to raise the temperature of a specific unit of mass of a substance by one degree Celsius.

3. How does specific heat capacity affect an object's final temperature?

The specific heat capacity of a substance determines how much thermal energy it can store and release. The higher the specific heat capacity, the more energy it can absorb before its temperature increases. This means that substances with a higher specific heat capacity will have a lower final temperature after a given amount of energy is added.

4. What factors can affect the specific heat capacity of a substance?

The specific heat capacity of a substance can be affected by its molecular structure, density, and state (solid, liquid, or gas). It can also be influenced by external factors such as pressure and temperature.

5. How can the specific heat capacity of a substance be measured?

The specific heat capacity of a substance can be measured experimentally by heating a known mass of the substance and recording its change in temperature. The amount of energy required to raise the temperature can then be calculated and used to determine the specific heat capacity.

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