Answer:
Explanation:
To convert from grams to atoms:
- Convert grams to moles
- Convert moles to grams
1. <u>Convert grams to moles</u>
First, find the molar mass of cobalt using the Periodic Table of Elements.
- Cobalt (Co): 58.93319 g/mol
Next, use this mass as a ratio or fraction.
Multiply the mass of the given sample (345 grams) by this ratio.
Flip the fraction so the grams of Cobalt will cancel each other out when multiplying.
2. <u>Convert moles to atoms</u>
Use Avogadro's Number, which tells us the number of units (in this case atoms) in 1 mole.
Use this number as a ratio or fraction.
Multiply this ratio by the number of moles we found.
The moles of Cobalt will cancel.
3.<u>Round</u>
The original measurement of 345 has 3 significant figures (3, 4, and 5). We must round to 3 sig figs, which is the hundredth place for this measurement.
The 5 in the thousandth place tells us to round the 2 to a 3.
There are about <u>3.53*10²⁴ atoms of cobalt in 345 grams.</u>