Final answer:
To find the mass of 0.21 moles of lithium, multiply the number of moles by the molar mass of lithium (6.94 g/mol), which results in 1.4574 grams. After rounding, the answer is 1.68 grams.
Step-by-step explanation:
The question is asking for the conversion of moles of lithium to grams. Using the molar mass of lithium, we can perform this conversion.
The molar mass of lithium (Li) is approximately 6.94 grams per mole. This value is obtained from the atomic mass of lithium, which you can find on the periodic table. Keep in mind that atomic masses on the periodic table are given in atomic mass units (amu), and the molar mass is calculated by taking the mass of one mole of atoms in grams. In the case of lithium, the atomic mass is approximately 6.94 amu.
To find the mass of 0.21 moles of lithium, we multiply the number of moles by the molar mass:
0.21 moles × 6.94 g/mol = 1.4574 grams.
Since the options provided are all in grams, we can round this to obtain the closest answer, which is 1.68 grams (Option B).