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A sample of iron, which has a specific heat capacity of 0.449 Jg^-1℃^-1, is put into a calorimeter (see sketch at right) that contains 100.0 g of water. The iron sample starts off at container 93.3 °C and the temperature of the water starts off at 22.0 °C. When the temperature of the water stops changing it's 25.7 °C. The pressure remains constant at 1 atm.

Required:
Calculate the mass of the iron sample. Be sure your answer is rounded to 2 significant digits.


Answer :

Answer:

[tex]m_{iron}=32.1g[/tex]

Explanation:

Hello!

In this case, since the interaction between hot iron and cold water allows the heat transfer from iron to water and therefore we can write up the following energetic equation:

[tex]Q_{iron}+Q_{water}=0[/tex]

Whereas the heat terms can be written in terms of mass, specific heat and temperature change:

[tex]m_{iron}C_{iron}(T_f-T_{iron}) + m_{water}C_{water}(T_f-T_{water}) = 0[/tex]

So we solve for the mass of iron as follows:

[tex]m_{iron} = \frac{m_{water}C_{water}(T_f-T_{water})}{C_{iron}(T_f-T_{iron}) }[/tex]

Now, we plug in the given data to obtain:

[tex]m_{iron} = \frac{-100g*0.449\frac{J}{g\°C} (25.7\°C-22.0\°C)}{0.449\frac{J}{g\°C} (25.7\°C-93.3\°C) }[/tex]

[tex]m_{iron}=32.1g[/tex]

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