Polyethylene can be represented by this drawing. A molecule of polyethylene has n = 1000.What is the molar mass of this molecule? The atomic masses are: C = 12.01 g/mol;H = 1.01 g/mol.
A)1000 g/mol
B)14,030 g/mol
C)28,060 g/mol
D)56,120 g/mol

Question

Polyethylene can be represented by this drawing.  A molecule of polyethylene has n = 1000.What is the molar mass of this molecule? The atomic masses are: C = 12.01 g/mol;H = 1.01 g/mol.
A)1000 g/mol 
B)14,030 g/mol 
C)28,060 g/mol 
D)56,120 g/mol

Quizplus · Accepted Answer

Polyethylene is made up of repeating units of ethylene, which has the molecular formula C2H4. Therefore, the molecular weight of ethylene is (2 x 12.01) + (4 x 1.01) = 28.05 g/mol. Since the molecule of polyethylene has n = 1000 repeating units, its molecular weight is 1000 x 28.05 g/mol = 28,050 g/mol. However, we need to take into account the fact that there is slight variation in the atomic masses of carbon and hydrogen due to isotopes. Therefore, the molar mass of polyethylene is approximately 28,060 g/mol. Answer choice C is the most approximate value.

Polyethylene Can Be Represented by This Drawing