Let's convert 0.7 moles of He (helium) to atoms, using Avogadro's number.
Step 1: Identify Avogadro's Number
Avogadro's number (NA) is approximately 6.022 x 10^23 atoms per mole.
Step 2: Set Up the Conversion
To convert moles of He to atoms, use the following conversion factor:
1 mole He = Avogadro's Number (6.022 x 10^23) of He atoms
Step 3: Perform the Calculation
Now, plug in the given value (0.7 moles) and Avogadro's number into the conversion factor:
0.7 moles He * (6.022 x 10^23 atoms / 1 mole He)
Step 4: Cancel Units
Note that the unit "moles He" cancels out with "moles He" in the conversion factor, leaving you with the unit "atoms."
Step 5: Calculate the Result
Perform the multiplication:
0.7 moles He * (6.022 x 10^23 atoms / 1 mole He) = 4.2 x 10^23 atoms of He
So, there are 4.2 x 10^23 atoms of helium in 0.7 moles of He.