Calculate the number of He atoms present in 18g of He (He = 4u).2.71 × 1024 atoms2.7 × 1023 atoms 1.34 × 1024 atoms 1.34 × 1023 atoms
Question
Calculate the number of He atoms present in 18g of He (He = 4u).2.71 × 1024 atoms2.7 × 1023 atoms 1.34 × 1024 atoms 1.34 × 1023 atoms
Solution
To calculate the number of atoms in a given mass of an element, you can use the formula:
Number of atoms = (Given mass / Molar mass) x Avogadro's number
Given:
- The mass of He (Helium) is 18g
- The molar mass of He is 4g/mol (given in the question as 4u, where u is the atomic mass unit)
- Avogadro's number is 6.022 x 10^23 atoms/mol
Step 1: Divide the given mass by the molar mass = 18g / 4g/mol = 4.5 mol
Step 2: Multiply the result by Avogadro's number = 4.5 mol x 6.022 x 10^23 atoms/mol = 2.71 x 10^24 atoms
So, the number of He atoms present in 18g of He is 2.71 x 10^24 atoms.
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