A 100 mL sample of propane gas is collected by water displacement. If the temperature of the water is 19 ?C and the barometric p
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Answer:
Explanation:
<u>1. Convert Grams to Moles</u>
Use the molar mass (found on the Periodic Table) to convert from grams to moles.
- Boron (B): 10.81 g/mol
Use this value as a ratio.
Multiply by the given number of grams.
Flip the ratio so the grams of boron cancel out.
<u>2. Convert Moles to Atoms</u>
We use Avogadro's Number, 6.02*10²³: the number of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case, the particles are atoms of boron.
Multiply by the number of moles we calculated.
The moles of boron cancel.
The original value of grams has 4 significant figures, so our answer should have the same. For the number we calculated, that is the thousandth place.
The 6 tells us to round the 2 to a 3.
25.00 grams of boron is equal to 1.393*10²⁴ atoms.
