The electrons and protons would be the same amount than take the atomic mass-the atomic number get the answer that way
<span>Answer:
Q = 500.0 x 4.18 x 8.63 = 18037 J => 18.037 kJ
moles anthracene = 0.455 g/ 178.234 g/mol=0.00255
0.00255 moles give 18.037 kJ
0.00255 : 18.037 = 1 mole : x
x = 7073 kJ/mol
enthalpy = - 70.73 kJ/mol</span>
Answer:
the compound contains C, H, and some other element of unknownidentity, so we can’t calculate the empirical formula
Explanation:
Mass of CO2 obtained = 3.14 g
Hence number of moles of CO2 = 3.14g/44.0 g = 0.0714 mol
The mass of the carbon in the sample = 0.0714 mol × 12.0g/mol = 0.857 g
Mass of H2O obtained = 1.29 g
Hence number of moles of H2O = 1.29g/18.0 g = 0.0717 mol
The mass of the carbon in the sample = 0.0717 mol × 1g/mol = 0.0717 g
% by mass of carbon = 0.857/1 ×100 = 85.7 %
% by mass of hydrogen = 0.0717/1 × 100 = 7.17%
Mass of carbon and hydrogen = 85.7 + 7.17 = 92.87 %
Hence, there must be an unidentified element that accounts for (100 - 92.87) = 7.13% of the compound.
