Heat Problems (answers)
Mr. pressly is the best
Calculate the following. Show your work and write out the formula you use. Specific heat water, steam and ice on yellow packet.
- How much heat is required to raise the temperature of 300.0 grams of aluminum from 22oC to 55oC? The specific heat of aluminum is 0.21 cal/g oC.
Q= mCT 300(0.21)(33) = 2079cal
- How much heat in joules is required to raise the temperature of 25.0 grams of liquid water from 9 oC to 29 oC?
Q= mCT25(4.18)20 = 2090J
- How much heat is absorbed when 56.8 grams H2O at 100 oC and 1 atm is converted to steam at 100oC? Give answer in kilojoules.
Q=mHv56.8g(2260) = 128368J = 128.368kJ
- How much heat is required to raise the temperature of 132.0 grams of chloroform from 58oC to 89oC? The specific heat of chloroform is 0.96 J/g oC.
Q= mCT132.0 g(0.96)(31) = 3928.32
- How much heat in joules is required to raise the temperature of 34.0 grams of liquid water from 10 oC to 67 oC?
Q= mCT34.0g (4.18) (57) = 8100.84
- How many kilojoules are required to melt a 18.0 g popsicle at 0 oC. Assume the popsicle has the same heat of fusion as water.
Q=mHf18.0g(334J/g) = 6012J =6.012kJ
- How much heat is required to convert 34.0 grams of water at 45 oC completely to steam at 100 oC? (2 steps)
1st step Q= mCT 2nd step Q=mHvadd two together
=34.0(4.18)(55)=34.0g(2260)7816.6 + 76840 = 84656.6
= 7816.6J=76840J
- How much heat is required to convert 65.0 grams of ice at -5 oC completely to water at 0 oC? (2 steps)
1st step Q= mCT 2nd step Q=mHf add two together = 22376.25 J
C= 2.05 for ice
65 (2.05)(5) +65(334)
- How much heat is required to convert 1.0 grams of ice at 0 oC completely to water at 0 oC? Q=mHf = 334J
- How much heat is required to raise the temperature of 1.89 X 102 grams of iron from 3K to 45K? The specific heat of iron is 0.46 J/g oC.
Q= mCT 189g (.46)(42K) = 3651.48
- How many grams of ice at 0 oC could be melted by the addition of 1.2 joules of heat?
Q= mHf 1.2J = m (334) solve for m = .0036gram or 3.6 X10-3
- How much heat is required to change 2.4 moles of liquid ammonia to gas at its normal boiling point. The heat of vaporization of ammonia is 23.4 kJ/mol.
Q= mHv2.4mole X 23.4 kJ/mol = 56.16 kJ
- How much heat is required to change 4.23 moles of solid oxygen to liquid at its normal melting point. The heat of fusion of O2 is 0.44 kJ/mol.
4.23 mole X .44 kJ/molQ= mHf = 1.86 kJ
- How much heat is required to change 35.4 grams of liquid methanol to gas at its normal boiling point. The heat of vaporization of methanol is 35.3 kJ/mol.
Q= mHf 35.4/32g (mass of methanol) = 1.10 moles X 35.3 kJ/mol = 39.05 kJ
- How much heat in joules is required to convert 2.5 moles of solid aluminum from 23 oC to 45oC?
Yellow packet specific heat of aluminum
Q= mCT 2.5mol X 27g/mol = 67.5 g (.897j/goC)(22oC) = 1332.045 J
- How much heat in joules is required to convert 1.00 mole of water from 45oC to 18oC? What is happening to the water?
Q= mCT get negative heat, cooling down 18grams(4.18J/g)(27) = 2031 J
- How much heat is required to convert 8.7 moles of ice at -4 oC completely to steam at 100 oC? Be careful (more than one step)
8.7 moles X 18g/mol = 156.6 grams H2O 4 steps
Q= mCT Q= mHf Q= mCT Q= mHv
156.6(2.05)(4) 156.6(334)156.6(4.18)(100)156.6(2260) =472,963J
- How much heat is required to convert 56.9 grams of ice at -2 oC completely to water at 100 oC? Be careful (more than one step)
Q= mCT Q= mHf Q= mCT
56.9(2.05)(2)=233.29 + 56.9(334)=19004.6 + 56.9(4.18)(100)=23784.2= 43022.09J