chemistry molar mass

Question

When 6 protons and 6 neutrons fuse, one nucleus of carbon-12 (C-12 or ¹²C⁶⁺) is formed.  When one nucleus of C-12 is formed, 1.64 × 10⁻²⁴ g of mass is lost.

a.     Calculate the mass loss when one mole of C-12 is formed. 

b.     Calculate the energy produced during the formation of 1 mole of C-12.

c.      When propane burns in oxygen (balanced chemical equation shown below), energy is produced.  For every one mole of propane that burns, 2220 kJ of heat are produced.  How many moles of propane would have to burn to produce the same amount of energy as is produced when one mole of C-12 is formed?

C₃H₈  + 5 O₂    3 CO₂  +  4 H₂O

d.     For fusion reactions matter is converted to energy, what causes the release of energy when propane burns in oxygen?  

Answer 1

a. Use Avogadro's number to convert from molecules to moles.

(1.64X10^-24 g/molecule) X (6.02X10²³ molecules/mol)=0.9873 g/mol)

b. Use Einstein's famous equation, E=mc², to convert mass (in kilograms) to energy.

E=(0.9873 g) X (1 Kg/1000 g) X (3.00 X 10⁸ m/s)² = 8.89 X 10¹³ J

c. To find the ratio (R), convert 2220 kJ to J, then divide the energies of the two reactions,

R=(8.89 X 10¹³ J)/(2.22 X 10⁶ J/mol)=4.00 X 10⁷ mol

d. Energy is released when the C-H bonds in propane break to form C-O bonds and H-H bonds.