A is the answer. Chemical changes happen when atomic bonds are broken or created during chemical reactions. Hence, in this case, it involve changes to molecular structure.
- Change in states are physical changes.
- When salts are dissolved in water, you can use Distillation to separate them. Distillation is a physical change as well.
- Dissolving is just physical change.
6.02 x 10^23 moles of representative particles
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.
It allowed him to realize that the mass of an atom is concentrated at its center because the atoms mostly went through the foil but some were deflected. He also realized that an atom probably wasn't just empty space and scattered electron and it had a positive center.
