Multiple Choice
A sample contains 351 kg of calcium (Ca). How many moles of calcium are present in the sample? (Molar mass of Ca = 40.08 g/mol)
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2. Atoms & Elements
Mole Concept
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How many moles of chlorine atoms are present in 71.0 g of Cl\(_2\)?
A
4.00 moles
B
2.00 moles
C
0.500 mole
D
1.00 mole
Verified step by step guidance1
Identify the molecular formula of chlorine gas, which is Cl\(_2\), meaning each molecule contains 2 chlorine atoms.
Calculate the molar mass of Cl\(_2\) by adding the atomic masses of two chlorine atoms. The atomic mass of Cl is approximately 35.45 g/mol, so the molar mass of Cl\(_2\) is \$2 \times 35.45$ g/mol.
Determine the number of moles of Cl\(_2\) molecules in 71.0 g by using the formula: \(\text{moles of Cl}_2 = \frac{\text{mass of Cl}_2}{\text{molar mass of Cl}_2}\).
Since each mole of Cl\(_2\) contains 2 moles of chlorine atoms, multiply the moles of Cl\(_2\) by 2 to find the moles of chlorine atoms: \(\text{moles of Cl atoms} = 2 \times \text{moles of Cl}_2\).
This final value gives the number of moles of chlorine atoms present in 71.0 g of Cl\(_2\).
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