To determine the number of formula units in 200 grams of calcium (Ca), we need to follow a few steps involving atomic mass, moles, and Avogadro’s number.
Step 1: Determine the Atomic Mass of Calcium
The atomic mass of calcium (Ca) is 40.08 g/mol. This means that 1 mole of calcium weighs 40.08 grams.
Step 2: Calculate the Number of Moles in 200 Grams
We use the formula:
Moles=MassMolar Mass\text{Moles} = \frac{\text{Mass}}{\text{Molar Mass}} Moles of Ca=200 g40.08 g/mol\text{Moles of Ca} = \frac{200 \text{ g}}{40.08 \text{ g/mol}} ≈4.99 moles\approx 4.99 \text{ moles}
Step 3: Convert Moles to Formula Units
Since 1 mole of any substance contains Avogadro’s number of formula units (6.022×10236.022 \times 10^{23} particles/mol), we multiply:
Formula Units=Moles×Avogadro’s Number\text{Formula Units} = \text{Moles} \times \text{Avogadro’s Number} =4.99×6.022×1023= 4.99 \times 6.022 \times 10^{23} ≈3.00×1024 formula units\approx 3.00 \times 10^{24} \text{ formula units}
Final Answer:
200 grams of calcium contains approximately 3.00×10243.00 \times 10^{24} formula units of Ca.
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