I need help

I getting the wrong the answer

I am

trying to find the specific heat capacity of brass
using copper calorimeter


Data :
mass of brass bob= 32.5gm
mass of calorimeter = 39.7 gm
mass of water + calorimeter = 93.9gm

mass of water = 93.9 - 39.7 = 54.2g

specific heat of water = 4.2 j/gm deg Cel
specific heat of copper = 0.382 j/gm deg cel

Temp of water = 23 deg cel
Temp of brass = 94 deg cel

temp of mixture = 47 deg cel





formulas used..

part A

(Mc*cc + Mw*cw)(T1-T2)

(mass of the calorimeter* specific heat of the calorimeter + mass of the water*specific heat of the water)*Fall in the temperature.


Part B
C=H/mΔT



part A being solved

(mass of the calorimeter* specific heat of the calorimeter + mass of the water*specific heat of the water)*Fall in the temperature.

(39.7 * 0.386) + (54.2 * 4.2) * (47-23)
(15.3242 + 227.64) * 24

242.9642 * 24

5831.1408

part b being solved.

C=H/mΔT
= 5831.1408/ 32.5 * 47

= 5831.1408 / 1527.5

= 3.8174407856

specific heat of brass = 3.8174407856 j/gm deg cel




this answer is wrong

the expected answer is 0.3817

where am I going wrong...

please help..

Your answer is correct, given the data you provided. As for why the answer given is off by a factor of ten - perhaps it's just an error on their answer sheet. However, in reality the specific heat of brass is very low, like copper, so I'm guessing that perhaps there is a typo in the mass of the brass that you were given - perhaps it should be 325 grams rather than 32.5?

My only quibble with your work is that you should never take a calculation to 12 decimal places of accuracy (3.8174407856) when the data you've been given is good to only three places. The proper answer is 3.82 J/(g C)

Quote:

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Originally Posted by ebaines

Your answer is correct, given the data you provided. As for why the answer given is off by a factor of ten - perhaps it's just an error on their answer sheet. However, in reality the specific heat of brass is very low, like copper, so I'm guessing that perhaps there is a typo in the mass of the brass that you were given - perhaps it should be 325 grams rather than 32.5?

My only quibble with your work is that you should never take a calculation to 12 decimal places of accuracy (3.8174407856) when the data you've been given is good to only three places. The proper answer is 3.82 J/(g C)

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Sir thanks for your reply

But I checked the mass it is 32.5

Not 325

I too doubt that there is some issue with a decimal point

But I can't figure out

Ya I'll use fractions only till 3dp

I'll avoid 12 dp