1. The following information is given for mercury at 1 atm: A 43.80 g sample of
ID: 1002387 • Letter: 1
Question
1. The following information is given for mercury at 1 atm:
A 43.80 g sample of liquid mercury is initially at 223.80 °C. If the sample is heated at constant pressure (P = 1 atm), ___ kJ of energy are needed to raise the temperature of the sample to 379.70 °C.
2.
The following information is given for manganese at 1atm:
A 49.60 g sample of solid manganese is initially at 1.225×103 ° C. If 2.171×104J 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 at a temperature greater than 1.244×103 °C.
The sample is a solid in equilibrium with liquid.
The sample is at a temperature of 1.244×103 °C.
The sample is a gas.
3.
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 27.70 g sample of liquid lead at 540.0 °C is poured into a mold and allowed to cool to 29.0 °C. How many kJ of energy are released in this process. Report the answer as a positive number.
___ kJ
boiling point = 356.60 °C Hvap(356.60 °C) = 295.6 J/g melting point = -38.90 °C Hfus(-38.90 °C) = 11.60 J/g specific heat gas = 0.1040 J/g°C specific heat liquid = 0.1390 J/g°CExplanation / Answer
1)
q = m * s * dT + m * dHvap + m * s * dT
q = 43.80 * 0.1040 * (379.7 - 356.6) + 43.8 * 295.6 + 43.8 * 0.139 * (356.6 - 223.8)
q = 13861.018 J
2)
q = m * s * dT + m * dH fus + m * s * dT
2.171 * 10^4 = 49.6 * 0.477 * ((1.244*10^3) - (1.225*10^3)) + 49.6 * 266.5 + 49.6 * 0.837 * (T - (1.244 * 10^3)) Final temperature T = 1.4277 * 10^3
so answers are a) the sample is liquid b) the sample is at a temperature greater than 1.244 * 10^3
3)
q = m * s * dT + m * dH fus + m * s * dT + m * dH vap
q = 27.7 * 0.13 * (29 - 328) + 27.7 * 23 + 27.7 * 0.138 * (328 - 540)
q = -1249.99 J
q = -1.25 kJ
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