Question

How many molecules are there in 0.655 moles of C6H14

Answer 1

`\boxed {\boxed {\sf 3.94 *10^(23) \ molecules \ C_6 H_ {14} }}}`

Step-by-step 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.

`\frac {6.022 *10^(23) \ molecules \ C_6H_(14)}{1 \ mol \ C_6H_(14)}`

Multiply by the given number of moles: 0.655

`0.655 \ mol \ C_6H_(14) * \frac {6.022 *10^(23) \ molecules \ C_6H_(14)}{1 \ mol \ C_6H_(14)}`

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.

`0.655 * \frac {6.022 *10^(23) \ molecules \ C_6H_(14)}{1 }`

`0.655 * {6.022 *10^(23) \ molecules \ C_6H_(14)}`

`3.94441*10^(23) \ molecules C_6H_(14)`

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.

• 3.94441

The 4 in the thousandth place tells us to leave the 4 in the hundredth place.

`3.94 *10^(23) \ molecules \ C_6H_(14)`

0.655 moles of hexane is equal to approximately 3.94 *10²³ molecules of hexane.