Calculate the mass, in grams, of 1.8 x 1020 atoms of iron, Fe.
The correct answer and explanation is:
To calculate the mass of 1.8 x 10²⁰ atoms of iron (Fe), follow these steps:
Step 1: Find the number of moles of iron atoms.
The number of atoms given is 1.8 x 10²⁰ atoms. The number of atoms in one mole of any substance is Avogadro’s number, which is approximately 6.022 x 10²³ atoms/mol. Moles of Fe=Number of atomsAvogadro’s number=1.8×10206.022×1023\text{Moles of Fe} = \frac{\text{Number of atoms}}{\text{Avogadro’s number}} = \frac{1.8 \times 10^{20}}{6.022 \times 10^{23}}
Calculating the above: Moles of Fe=2.99×10−4 mol\text{Moles of Fe} = 2.99 \times 10^{-4} \text{ mol}
Step 2: Calculate the mass using molar mass.
The molar mass of iron (Fe) is approximately 55.85 grams per mole. Mass=moles×molar mass=2.99×10−4×55.85\text{Mass} = \text{moles} \times \text{molar mass} = 2.99 \times 10^{-4} \times 55.85
Calculating the above: Mass=0.0167 grams\text{Mass} = 0.0167 \text{ grams}
Final answer:
The mass of 1.8 x 10²⁰ atoms of iron is approximately 0.0167 grams.
Explanation:
Atoms are extremely small particles, so dealing with individual atoms directly in grams is not practical. Instead, the concept of the mole allows conversion between the number of atoms and a measurable mass. Avogadro’s number is the key constant here. It states that one mole contains exactly 6.022 x 10²³ atoms. Using this number, the quantity of atoms can be converted to moles.
After finding the number of moles from the given atoms, the molar mass, which tells how many grams one mole of the element weighs, is used to find the actual mass. Iron’s molar mass is about 55.85 g/mol, meaning one mole of iron atoms weighs 55.85 grams.
This two-step process (atoms to moles, then moles to grams) is commonly used in chemistry to convert microscopic quantities to everyday measurable masses. The calculation shows that even a very large number of atoms, like 1.8 x 10²⁰, corresponds to a very small mass because atoms are so tiny.