Answer:
Step-by-step explanation:
We are asked to find how many atoms are in 1 gram of mercury.
1. Convert Grams to Moles
First, we convert grams to moles. We use the molar mass or the mass of 1 mole of a substance. These values are equivalent to the atomic masses on the Periodic Table, but the units are grams per mole instead of atomic mass units.
Look up mercury's molar mass.
We convert using dimensional analysis, so we create a ratio using the molar mass.
We are converting 1 gram of mercury to moles, so we multiply the ratio by this value.
Flip the ratio so the units of grams of mercury cancel out.
2. Convert Moles to Atoms
Next, we convert moles to atoms. We use Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units) in 1 mole of a substance. In this case, the particles are atoms of mercury.
We will use dimensional analysis and set up another ratio.
Multiply by the number of moles we calculated.
The units of moles of mercury cancel.
3. Round
The original measurement of grams has 1 significant figures, so our answer must have the same. For the number we calculated, that is the ones place. The 0 in the tenths place tells us to leave the 3 in the ones place.
There are approximately 3×10²¹ atoms of mercury in 1 gram of mercury.