Answer:
[tex]\boxed {\boxed {\sf 3.94 *10^{23} \ molecules \ C_6 H_ {14} }}}[/tex]
Explanation:
1 mole of any substance has the same number of particles: 6.022 * 10²³. This number is as Avogadro's Number.
The particles can be molecules, atoms, formula units, etc. For this problem, the particles are molecules of C₆H₁₄ or hexane.
We can set up a ratio using Avogadro's Number.
[tex]\frac {6.022 *10^{23} \ molecules \ C_6H_{14}}{1 \ mol \ C_6H_{14}}[/tex]
Multiply by the given number of moles: 0.655
[tex]0.655 \ mol \ C_6H_{14} * \frac {6.022 *10^{23} \ molecules \ C_6H_{14}}{1 \ mol \ C_6H_{14}}[/tex]
The moles of hexane will cancel, because one is the "numerator" (techincally 0.655 is over 1) and the other is in the denominator of the ratio.
[tex]0.655 * \frac {6.022 *10^{23} \ molecules \ C_6H_{14}}{1 }[/tex]
[tex]0.655 * {6.022 *10^{23} \ molecules \ C_6H_{14}}[/tex]
[tex]3.94441*10^{23} \ molecules C_6H_{14}[/tex]
The original value of moles has three significant figures, so our answer must have the same. For the number we found, that is the hundredth place.
The 4 in the thousandth place tells us to leave the 4 in the hundredth place.
[tex]3.94 *10^{23} \ molecules \ C_6H_{14}[/tex]
0.655 moles of hexane is equal to approximately 3.94 *10²³ molecules of hexane.
