HI can someone explain this problem to me and how to get theanswer. It says: Gra

Question

HI can someone explain this problem to me and how to get theanswer. It says: Graphite, the material in pencils used to write ormark with (and often times misepresented as pencil lead), has achemical formula of C. If a pencil contains 2.27g of graphite, howmany atoms of carbon are in the pencil lead?
the answer should be 3.77*10^-24 atoms.
THank YOU.

I also need help with this problem: In the combustion of 1.20g ofC3H6 a chemist isolates .560g of CO2. What is the percentage yieldin the reaction? THank YOU.

Explanation / Answer

Atomic mass of carbon is  M = 12 g Given mass of graphite m = 2.27 g No.of moles of Graphite i.e., carbon is n = m / M = 0.1891mol we know that 1 mole of graphite( C ) contains 6.023 *10 ^ 23 atoms 0.1891 moles of graphite contains = 0.1891 * 6.023 * 10 ^ 23atoms                                                   = 1.1393 * 10 ^ 23 atoms of carbon (2).2C 3H6+9O2 ==> 6CO2 + 6H2O molar mass of C3H6 is = 3* 12 + ( 6 * 1 ) = 42 g Molar mass of CO2 = 12 + 2( 16 ) = 44 g 2* 42 g of C3H6 on combuction produces 6* 44g of CO2 1.2 g of C3H6 on combuction produces Xg of CO2 X = ( 6 * 44 * 1.2 ) / (2* 42)     = 3.7714 g of CO2 So the theroitical yield = 3.7714 g actual yield = 0.56g of CO2 % yield = ( actual yield / theroritical yield ) *100            = 14.85 %

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