- The amount of heat required to melt 175 g Cu has been 35.8 kJ/mol.
- The mass of NaCl melted with 450.1 kJ heat has been 870.98 grams.
- The substance that has been required 14.9 kJ of energy for freezing 1 mole of sample has been Fe.
The energy required to melt 1 mole of a substance has been given as the heat of fusion. The heat energy required to vaporize 1 mole of a substance has been heat of vaporization.
Heat of vaporization
- The amount of heat required to melt 1 mole of Cu has been 13 kJ/mol. The moles of Cu equivalent to 175 gram has been:
\(\rm Moles=\dfrac{Mass}{Molar\;mass}\\Moles \;Cu =\dfrac{175}{63.5}\\Moles\;Cu=2.755\;mol\)
The available moles of Cu has been 2.755 mol.
The heat for melting 1 mole of Cu has been 13 kJ/mol. The heat for melting 2.755 mole of Cu has been:
\(\rm 1\;mol=13\;kJmol\\2.755\;mol=2.755\;\times\;13\;kJ/mol\\2.755\;mol= 35.8\;kJ/mol\)
The amount of heat required to melt 175 g Cu has been 35.8 kJ/mol.
- The amount of heat that can melt 1 mole of NaCl has been 30.2 kJ/mol. The amount of sample melted by 450.1 kJ/mol heat has been:
\(\rm 30.2\;kJ/mol=1\;mol\;NaCl\\450.1\;kJ/mol=\dfrac{1}{30.2}\;\times\;450.1\;mol\;NaCl\\450.1\;kJ/mol=14.90\;mol\;NaCl\)
The moles of NaCl sample melted has been 14.90 mol. The mass of NaCl sample has been:
\(\rm Mass=Moles\;\times\;Molar\;mass\\Mass\;NaCl=14.9\;\times\;58.44\\Mass\;NaCl=870.98\g\\\)
The mass of NaCl melted with 450.1 kJ heat has been 870.98 grams.
- The energy required by an atom to freeze a 1.42 mol sample has been 21.2 kJ/mol. The energy of 1 mole of sample has been:
\(\rm 1.42\;mol=21.2\;kJ\\1\;mol=\dfrac{21.2}{1.42} \\1\;mol=14.92\;kJ\)
The substance that has been required 14.9 kJ of energy for freezing 1 mole of sample has been Fe.
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