Answer:
[tex]\boxed {\boxed {\sf 9.15*10^{24} \ atoms \ K}}[/tex]
Explanation:
To convert atoms to moles, Avogadro's Number must be used: 6.022*10²³.
This tells us the amount of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case it is the atoms of potassium. We can create a ratio.
[tex]\frac {6.022*10^{23} \ atoms \ K }{ 1 \ mol \ K }[/tex]
Multiply by the given number of moles: 15.2
[tex]15.2 \ mol \ K *\frac {6.022*10^{23} \ atoms \ K }{ 1 \ mol \ K }[/tex]
The moles of potassium cancel.
[tex]15.2 *\frac {6.022*10^{23} \ atoms \ K }{ 1 }[/tex]
The denominator of 1 can be ignored.
[tex]15.2 * {6.022*10^{23} \ atoms \ K }{[/tex]
Multiply.
[tex]9.15344*10^{24} \ atoms \ K[/tex]
The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we calculated that is the hundredth place. The 3 in the thousandth place tells us to leave 5.
[tex]9.15*10^{24} \ atoms \ K[/tex]
In 15.2 moles of potassium, there are 9.15*10²⁴ atoms of potassium.
