Multiple Choice
A compound containing only carbon and hydrogen has a carbon-to-hydrogen mass ratio of 11.89. Which of the following carbon-to-hydrogen mass ratios is possible for another compound composed only of carbon and hydrogen?
2. Atoms & Elements
Mole Concept
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How many aluminum atoms are there in 3.50 grams of Al₂O₃?
A
8.26 x 10^22 atoms
B
2.07 x 10^22 atoms
C
4.13 x 10^22 atoms
D
1.24 x 10^23 atoms
Verified step by step guidance1
Determine the molar mass of Al₂O₃ by adding the atomic masses of 2 aluminum atoms and 3 oxygen atoms. Use the periodic table for atomic masses: Al = 26.98 g/mol, O = 16.00 g/mol.
Calculate the number of moles of Al₂O₃ in 3.50 grams by using the formula: \( \text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \).
Use the stoichiometry of the compound Al₂O₃ to find the number of moles of aluminum atoms. Since there are 2 moles of Al in 1 mole of Al₂O₃, multiply the moles of Al₂O₃ by 2.
Convert the moles of aluminum atoms to the number of atoms using Avogadro's number \(6.022 \times 10^{23}\) atoms/mol. Use the formula: \( \text{atoms} = \text{moles} \times 6.022 \times 10^{23} \).
Review the calculation steps to ensure all conversions and multiplications are correctly applied to find the number of aluminum atoms in 3.50 grams of Al₂O₃.
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