Question

A mothball, composed of naphthalene (C10H8), has a mass of 1.72 g .How many naphthalene molecules does it contain?

Answer 1

To go to mass to number of particles, these are the steps:
Mass divided by molar mass gives moles
moles x avogadros number [will be using 6.02x10^23] gives number of particles.

So:
1.72/128.17 = 0.0134 moles.
0.0134 x 6.02x10^23= 8.07xx10^21 molecules of naphthalene. [rounded to 3 significant figures]

Answer 2

Answer:
`0.0809* 10^(23)`

Step-by-step explanation:

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number
`6.023* 10^(23)` of particles.

To calculate the number of moles, we use the equation:

`{\text{Number of moles}}=\frac{\text{Given mass}}{\text{Molar mass}}`

`{\text{Number moles}}=(1.72g)/(128g/mol)=0.0134moles`

1 mole of napthalene
`C_(10)H_8` contains =
`6.022* 10^(23)` molecules

Thus 0.0134 moles of napthalene
`C_(10)H_8` contain=
`(6.022* 10^(23))/(1)* 0.0134=0.0809* 10^(23)` molecules

Thus there are
`0.0809* 10^(23)` napthalene molecules.