What is the percent composition of carbon in heptane c7h16

What is the percent composition of carbon in heptane c7h16

Answers

the percent composition of carbon in heptane is 83.9%

Explanation:

1) Atomic masses of the atoms:

C: 12.01 g/molH: 1.008 g/mol

2) Molar mass of heptane:

C₇H₁₆: 7 × 12.01 g/mol + 16×1.008 g/mol = 100.2 g/mol

3) Mass of carbon in one mole of heptane:

C₇: 7 × 12.01 g/mol = 84.07 g/mol

3) Percent composition of carbon:

% = (mass in grams of C) / (mass in grams of C₇H₁₆) × 100 =

           = (84.07 g/ 100.2 g) × 100 = 83.9% ← answer

83.90 percent.

Option d, 84%

Explanation:

1) Determine the molar mass of the heptane

element   # of atoms    atomic mass        total mass      

  C              7                  12.011 g/mol         7×12.011 g/mol = 84.077 g/mol

  H             16                  1.008 g/mol         16×1.008 g/mol = 16.128 g/mol

                                                                                               

                                                                   Molar mass =    100.205 g/mol

2) Percent of carbon, %

% = (mass of element / molar mass )×100

           = (84.077 g/mol / 100.205 g/mol )×100 = 83.83 %

Round to two significant figures: 84% ← answer

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