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Calorimetry Lab Analysis (predict specific heat of unknown metal)

Problem Statement
so we did an experiment. basically the teacher gave us each a cube of unknown metal
and we had to figure out what it was using the specific heat.

we put the metal in boiling water until it was 212C
and then we put it in room temp water
and we measured how much it heated the water

he also gave us some lead to find the specific heat of so we can troubleshoot if our data is wrong because of the lab process or the calculation

check out the attached files for more precise instructions

so my results are in this google sheets
i set it so anyone with link can view so you guys should have no problem viewing it
https://docs.google.com/spreadsheets/d/1StBNPECq3Ny0tK_N6-0DT4JGgR_bm3tCwsx2dP8RO_0/edit?usp=sharing

i tried making formulas on some of the data so that i didnt have to do the calculations by hand but something is wrong. im getting 50 J/gC (joules per grams degrees celcius) for my unknown metal, which has to be wrong because the specific heat of water is 4.184 J/gC and water is known to have a high specific heat

please help me
im not sure if this is because of my procedure or my calculations
thank you
Relevant Equations
final temperature minus initial temperature = change in temperature
specific heat times mass times change in temp. = change in heat
Problem Statement: so we did an experiment. basically the teacher gave us each a cube of unknown metal
and we had to figure out what it was using the specific heat.

we put the metal in boiling water until it was 212C
and then we put it in room temp water
and we measured how much it heated the water

he also gave us some lead to find the specific heat of so we can troubleshoot if our data is wrong because of the lab process or the calculation

check out the attached files for more precise instructions

so my results are in this google sheets
i set it so anyone with link can view so you guys should have no problem viewing it
https://docs.google.com/spreadsheets/d/1StBNPECq3Ny0tK_N6-0DT4JGgR_bm3tCwsx2dP8RO_0/edit?usp=sharing

i tried making formulas on some of the data so that i didnt have to do the calculations by hand but something is wrong. im getting 50 J/gC (joules per grams degrees celcius) for my unknown metal, which has to be wrong because the specific heat of water is 4.184 J/gC and water is known to have a high specific heat

please help me
im not sure if this is because of my procedure or my calculations
thank you
Relevant Equations: final temperature minus initial temperature = change in temperature
specific heat times mass times change in temp. = change in heat

the above is my data from my lab

ive tried to do calculations on paper but i get the same results as in the above spreadsheet
but i know that specific heat is way off...
 

Attachments

i dont know what you guys consider to be introductory or advanced physics but i put it in advanced cus i thought it was pretty hard lol
 

tech99

Gold Member
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527
"tf water" may be a mistake, as for calculation purposes this is the initial temp of the metal. The final temp of the water is about 26C and not around boiling. I also notice you have confused Centigrade and Fahrenheit for the boiling water.
 
19,077
3,732
Let's see the equations you used. If you don't show us those, how are we supposed to help you?
 
"tf water" may be a mistake, as for calculation purposes this is the initial temp of the metal. The final temp of the water is about 26C and not around boiling. I also notice you have confused Centigrade and Fahrenheit for the boiling water.
the water ti and tf is how much the room temperature water was heated once the metal (at 212 C) was placed into it. so it goes from about 21 to 26 because the water has high specific heat so it is hard to raise its temperature even if a block of boiling metal is placed into it.
the metal ti and tf however is how much the metal was heated once placed into boiling water. so that would be from 21 to 212.

as i said earlier the procedure went as follows:
put metal into boiling water
metal is now at boiling temperature
put that same metal into room temp water
see how much the room temp water heats
calculate specific heat of metal
use that to identify the metal
 
Let's see the equations you used. If you don't show us those, how are we supposed to help you?
final temperature minus initial temperature = change in temperature
specific heat times mass times change in temp. = change in heat
SH * m * delta T = delta H

i dont think we need the ideal law of gases even though we learned it along with these formulas in class but i might be wrong
 
19,077
3,732
I still can't tell from the "equation" you wrote what you did. Here is my understanding of the equation to use: $$m_{cube}C_{cube}(T_{0, cube}-T_{final})=m_{water}C_{water}(T_{final}-T_{0,water})$$where the subscript 0 refers to the initial temperatures of the cube and the water, and the subscript final refers to the final equilibrated temperature of both the cube and water. Is this what you were trying to write? If so, you need to be more precise in writing your equations. If not, where do we differ and why?
 
I still can't tell from the "equation" you wrote what you did. Here is my understanding of the equation to use: $$m_{cube}C_{cube}(T_{0, cube}-T_{final})=m_{water}C_{water}(T_{final}-T_{0,water})$$where the subscript 0 refers to the initial temperatures of the cube and the water, and the subscript final refers to the final equilibrated temperature of both the cube and water. Is this what you were trying to write? If so, you need to be more precise in writing your equations. If not, where do we differ and why?
yes! that is exactly what i wanted
thats what we learned in class

how did you write that in here lol
 
mass of water * change in temp of water * specific heat of water = change in heat of water AND cube = mass of cube * change in temp of cube * specific heat of cube

because we know that the change in heat is equal between the water and the cube we can set it equal

because even though the change in temp is different, the change in heat is equal
 
19,077
3,732
specific heat of cube = mass of water * change in temp of water * specific heat of water / change in temp of cube / mass of cube

in which / means divide and * means multiply
 
SP cube = 30 * 187.5 * 4.184 / 3.8 / 121.5
SP cube = 50.97

but it should not be 50.97
because the specific heat of water is 4.184
and water is known to have a high specific heat
and metals almost always have specific heats of less than 1

so something is wrong here
 
Are you taking into account that the calorimeter will have loses?
 
Are you taking into account that the calorimeter will have loses?
we are not using a calorimeter
we are using thermometers

there will be inaccuracies in our data because the time it takes to put the boiling metal from the boiling water to the room temp water will affect the accuracy a bit
 

ZapperZ

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Education Advisor
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You are still not acknowledging that you are confusing temperature in F and C. You kept writing that the boiling temperature is 212 C. This is incorrect. It is at 212 F or 100 C. And in using the specific heat equation, the change in temperature must be in C (or K), not F.

Zz.
 
You are still not acknowledging that you are confusing temperature in F and C. You kept writing that the boiling temperature is 212 C. This is incorrect. It is at 212 F or 100 C. And in using the specific heat equation, the change in temperature must be in C (or K), not F.
ohhhhhhhh
im sorry. thank you for explaining it more clearly. i will go change it

also i dont think change in C or change in K matters
because K is just C + 273.15
so the change would be the same
and in class we learned it with C
 

ZapperZ

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Science Advisor
Education Advisor
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2018 Award
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ohhhhhhhh
im sorry. thank you for explaining it more clearly. i will go change it

also i dont think change in C or change in K matters
because K is just C + 273.15
so the change would be the same
and in class we learned it with C
Isn't that what I wrote? I said ".. in using the specific heat equation, the change in temperature must be in C (or K), not F.... ".

I included "K" to be complete in case you are going on further and start to deal with the ideal gas law. In such a case, the absolute temperature is required, not just the change in temperature.

Zz.
 
Isn't that what I wrote? I said ".. in using the specific heat equation, the change in temperature must be in C (or K), not F.... ".

I included "K" to be complete in case you are going on further and start to deal with the ideal gas law. In such a case, the absolute temperature is required, not just the change in temperature.

Zz.
do you think i need ideal gas law?
and do you think you can help me with the thing on google sheets?
 
also i cant seem to edit the original post
 
19,077
3,732
How can the final temperature of the water be different from the final temperature of cube at equilibrium? And, how did you measure the final temperature of the cube?
 
How can the final temperature of the water be different from the final temperature of cube at equilibrium? And, how did you measure the final temperature of the cube?
the initial temp of the cube if before i put it into the boiling water
the final temp of the cube is after i put it in the boiling water for a couple minutes
the initial temp of the water is room temp (before i put the boiling cube in)
the final temp of the water is the highest temp the room temp water becomes after putting the cube in
 
And, how did you measure the final temperature of the cube?
i did not need to measure the final temp of the cube because boiling water is always 100C
so the cube must be 100C after a couple minutes
 
What could possibly make you think this?
well the formula ive been using doesnt seem to give me the right answer
it gives me 20 something J/gC
when i should be getting less than 1 J/gC
 

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