suppose you are given 50g of an unknown material and you have to determine what

Question

suppose you are given 50g of an unknown material and you have to determine what it is. Using the equipment, you determine that the initial temperature of the material is 20C and when you put it in the Dewar flask 7.0g of nitrogen evaporate by absorbing heat from the material. What is the specific heat of the material? Assume you have already accounted for the nitrogen that evaporates due to contact with the air in the room. 390 J/(kg C), therefore the material could be copper. 130 J/(kg C), therefore the material could be gold. 230 J/(kg C), therefore the material could be silver. 450 J/(kg C), therefore the material could be iron.

Explanation / Answer

Here ,

for the N2 , final tempeature , Tf = -195.8 degree C

latent heat of vapourization of N2 , Lv = 200 J/gm

Now ,

heat lost by sample = heat gain by N2

50 * Sm * (20 - (-195.8)) = 200 * 7

solving for Sm

Sm = 0.13 J/(gm degree C)

Sm = 130 J/(Kg.degree C)

hence , for specific heat 130 J/(kg degree C), therefore the material could be gold.

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