The number average weight of a poly(styrene-butadiene) alternating copolymer is 1,350,000 gmol"! . determine the average number of styrene and butadiene mer units per molecule.

8544

Explanation:

Given:

An alternating copolymer,

thus, the number of both types of repeat units will be the same.

average weight of a poly(styrene-butadiene)  = 1,350,000 g/mol

and,

there are 8 atomes of carbon and 8 atoms of hydrogen  in the styrene repeat unit,

also, There are 4 atoms of carbon and six atoms of hydrogen in butadiene repeat units.

Therefore,

when the styrene-butadiene is combined the total number of carbon atoms in a molecule will be ( 8 + 4 ) i.e 12 atoms

and, the total  number of Hydrogen atoms will be ( 8 + 6 ) i.e 14 atoms

Therefore, the total molecular weight will be

m = 12 × Molecular weight of the carbon + 14 × Molecular weight of the hydrogen

or

m = 12 × 12 g/mol + 14 × 1 g/mol

or

m = 158 g/mol

Now,

the average number of styrene and butadiene mer units per molecule will be

=  

= 8544.30 ≈ 8544

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).