if your lab partner determined that there were 4.030 x 1020 atoms of H in an unknown sample of C2H4Cl2, how many milligrams would the unknown sample weigh?
To determine the weight of the unknown sample, you need to know the molar mass of the compound C2H4Cl2, which includes two carbon atoms, four hydrogen atoms, and two chlorine atoms.
To calculate the molar mass, you can use the atomic masses of each element from the periodic table:
- Carbon (C) has a molar mass of approximately 12.01 grams/mole.
- Hydrogen (H) has a molar mass of approximately 1.008 grams/mole.
- Chlorine (Cl) has a molar mass of approximately 35.45 grams/mole.
Now, let's calculate the molar mass of C2H4Cl2:
(2 carbon atoms * 12.01 g/mol) + (4 hydrogen atoms * 1.008 g/mol) + (2 chlorine atoms * 35.45 g/mol) = 62.50 g/mol
The molar mass of C2H4Cl2 is approximately 62.50 grams/mole.
Next, we need to calculate the number of moles of H in the unknown sample using the given information. The given value is 4.030 x 10^20 atoms of H.
To convert from atoms to moles, you can use Avogadro's number, which is approximately 6.022 x 10^23 atoms/mole.
Now, let's calculate the number of moles of H:
(4.030 x 10^20 H atoms) / (6.022 x 10^23 atoms/mole) ≈ 0.000668 moles
The approximate number of moles of H in the unknown sample is 0.000668 moles.
To find the weight of the sample, multiply the number of moles by the molar mass of C2H4Cl2:
0.000668 moles * 62.50 grams/mole ≈ 0.042 grams
The weight of the unknown sample is approximately 0.042 grams or 42 milligrams.