200 g of an unknown metal powder at Thot = 72°C are dropped into a negligible he
ID: 2000170 • Letter: 2
Question
200 g of an unknown metal powder at Thot = 72°C are dropped into a negligible heat capacity calorimeter containing 150 g of water at 16°C. The final equilibrium temperature is measured to be 36.6°C.
1. Calculate the specific heat of the metal powder c. c = J/kg-°C 2. Identify the metal from the list below.
Water
Beryllium
Aluminum
Silicon
Iron
Copper
Silver
Gold
Lead
3. Using the data table, calculate the specific heat per mole Cmolar of each pure substance listed below, along with the specific heat per mol of your unknown metal found above. Then, divide the specific heat per mole you obtain by the "gas constant", R = 8.31 J/mol-K, and enter these results in the third column. These numbers are now dimensionless. This is a way of checking what is called classical corresponding states: that regardless of the type of substance, their specific heats per mole depend only on their state: gas or solid. Of course "real matter" varies from this rule, but not extraordinarily so.
4. Are these results close to 3? Discuss.
Substance C molar (J/mol -degrees C) C molar/R Water Iron Copper UnknownExplanation / Answer
heat lost by metal powder = heat gained by water
mw*cw*dT1 = mpoder*cpowdwer*dT2
0.15*4190*(36.6-16) = 0.2*Cpowdwer*(72-36.6)
Cpowder = 1824.32 J/Kg-oC
+++++++++
Cpowder is BEryllium
++++++++++++
water 4190*0.018 = 75.42 75.42/8.314 = 9.07
Iron 470*0.0559 = 26.273 26.273/8.314 = 3.16
copper 390*0.0635 = 24.765 24.765/8.314 = 2.98
unknown 1824.32*0.00901 = 16.44 16.44/8.314 = 1.98
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.