Answer:
14. there are 7.41 moles of Al in 200 grams of Al.
15. there are 0.98 moles of Al2O3 in 100 grams of Al2O3.
16. 1 mole of methane has 5 moles of atoms.
Step-by-step explanation:
14. To calculate the number of moles in 200 g divide the mass by the molar mass of Al. The molar mass of Al is 26.98 g/mol.
Number of moles = Mass ÷ Molar mass
Number of moles = 200 g ÷ 26.98 g/mol
Number of moles = 7.41 mol
Therefore, there are 7.41 moles of Al in 200 grams of Al.
15. To calculate the number of moles in 100 grams of Al2O3, divide the given mass by the molar mass of Al2O3. The molar mass of Al2O3 is 101.96 g/mol.
Number of moles = Mass ÷ Molar mass
Number of moles = 100 g ÷ 101.96 g/mol
Number of moles = 0.98 mol (rounded to two decimal places)
Therefore, there are 0.98 moles of Al2O3 in 100 grams of Al2O3.
16. One mole of methane, CH4, contains 1 mole of carbon and 4 moles of hydrogen. The total number of moles in 1 mole of methane:
Number of moles = Number of moles of carbon + Number of moles of hydrogen
Number of moles = 1 mole + 4 moles
Number of moles = 5 moles
Therefore, 1 mole of methane contains 5 moles of atoms.