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1.The following information is given for lead at 1atm: boiling point = 1.740×103

ID: 1023051 • Letter: 1

Question

1.The following information is given for lead at 1atm:

boiling point = 1.740×103 °C

Hvap(1.740×103 °C) = 858.2 J/g

melting point = 328.0 °C

Hfus(328.0 °C) = 23.00 J/g

specific heat solid = 0.1300 J/g°C

specific heat liquid = 0.1380 J/g°C

A 43.30 g sample of solid lead is initially at 318.0 °C. If the sample is heated at constant pressure (P = 1 atm), ____kJ of heat are needed to raise the temperature of the sample to 537.0 °C.

2.

The following information is given for manganese at 1atm:



A 35.20 g sample of solid manganese is initially at 1.228×103 ° C. If 9.846×103J of heat are added to the sample at constant pressure (P = 1 atm), which of the following are true.

Choose all that apply:

The sample is a liquid.

The sample is a solid in equilibrium with liquid.

The sample is at a temperature of 1.244×103 °C.

The sample is at a temperature greater than 1.244×103 °C.

The sample is a gas.

boiling point = 2.095×103 ° C Hvap(2.095×103 ° C) = 4.090×103J/g melting point = 1.244×103 ° C Hfus(1.244×103 ° C) = 266.5 J/g specific heat solid = 0.4770 J/g°C specific heat liquid = 0.8370 J/g°C

Explanation / Answer

1. Heat required for Pb from 318 oC to 537 oC

q1 = Pb(s) at 318 oC to Pb(s) at 328 oC

     = mCpdT = 43.30 x 0.13 x (328 - 318) = 56.29 J

q2 = Pb(s) at 328 oC to Pb(l) at 328 oC

     = 43.30 x 23 = 995.9 J

q3 = Pb(l) at 328 oC to Pb(l) at 537 oC

     = 43.30 x 0.1380 x (537 - 328) = 1248.86 J

Total heat required = q1 + q2 + q3 = 2301.05 J = 2.30 kJ

2. If 35.20 g of solid Mn at 1228 oC is supplied with 9846 J of heat, the following statements are true,

The sample is a liquid

The sample is at a temperature greater than 1.244×103 °C.