Experiment 11 Advance Study Assignment 1. A. Define specific heat. Pure s J s a

Question

Experiment 11 Advance Study Assignment 1. A. Define specific heat. Pure s J s a proper t B. Why do you have to transfer the copper rapidly from the boiling water into the calorimeter? C What error would be committed if the boiling water did not cover the metal completely? 2. A student places 1.38 g of unknown metal at 99.6 C into 60.50 g of water at 22-1 The entire system reaches a uniform temperature at 31.6 C. Calculate the specific heat of the metal- 3. If the actual specific heat of the metal in Problem 2 is 0.25 J/g C, calculate the percentage error. 161

Explanation / Answer

1.

A. Specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.

2) Heat lost by Metal , qmetal = Heat gained by water, qwater

mmetal x Cmetal x T = mwater x Cwater x T

(1.38 g) (Cmetal) (99.6 °C - 31.6 °C) = (60.50 g) (4.184 J g-1 oC-1) (31.6 °C – 22.1 °C)

(1.38 g) (Cmetal) (68.0 °C) = (60.50 g) (4.184 J g-1 oC-1) (9.5 °C)

Cmetal = [(60.50 g) (4.184 J g-1 oC-1) (9.5 °C) ] / [(1.38 g) (68.0 °C)]

Cmetal = 25 J g-1 oC-1

3) Actual specific heat = 0.25 J g-1 oC-1

Experimental specific heat = 25 J g-1 oC-1

% Error = [ (Experimental – actual) / Actual ] x 100

              = [ (25 – 0.25) / 0.25 ] x 100

              = [ 24.75 / 0.25 ] x 100

              = 9900 %

Image 2:

3.

Lower the specific heat higher is the rise in temperature for a given amount of supplied heat.

For example:

Aluminum 0.903 kJ/kg.K

Copper 0.385 kJ/kg K

This means that if you had 1 kg of each, you would need 0.91kJ to raise the temp. of Al by 1K (or 1C) but would only need 0.39 kJ for the same change in copper. So the same amount of heat would give a greater rise in temperature with copper.

4.

Aluminum 0.903 kJ/kg.K

Copper 0.385 kJ/kg K

Aluminum has higher specific heat. So, more heat is required for aluminium than copper. Hence Aluminium pot will take longer time.

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