Question

A solid sample (Sample 1) is analyzed and found to contain 1.47 g carbon and 0.123 g hydrogen. A second sample (Sample 2) is expected to be composed of the same pure compound. If Sample 2 is found to contain 2.17 g hydrogen, how much carbon is expected in the sample ?

Answer 1

Step-by-step explanation:

Here it is given that carbon is sample 2 = 25.9 g

• For sample 1, mass carbon = 1.47 g

No. of moles of carbon will be calculated as follows.

No. of moles of carbon =
`\frac{\text{mass carbon}}{\text{molar mass carbon}}`

=
`(1.47 g)/(12.01 g/mol)`

= 0.1224 mol

It is also given that mass of hydrogen = 0.123 g

Hence, calculate number of moles of hydrogen as follows.

No. of moles of hydrogen =
`\frac{\text{mass hydrogen}}{\text{molar mass hydrogen}}`

=
`(0.123 g)/(1.008 g/mol)`

= 0.122 mol

Therefore,
`\frac{\text{moles of carbon}}{\text{moles of hydrogen}}`

=
`(0.1224 mol)/(0.122 mol)`

= 1.003

• For sample 2, mass of hydrogen = 2.17 g

Therefore, calculate the number of moles of hydrogen as follows.

No. of moles of hydrogen =
`\frac{\text{mass hydrogen}}{\text{molar mass hydrogen}}`

=
`(2.17 g)/(1.008 g/mol)`

= 2.1528 mol

Hence, calculate the moles of carbon as follows.

Moles of carbon =
`\text{moles hydrogen} * \frac{\text{moles of carbon}}{\text{moles hydrogen}}`

=
`2.1528 mol * 1.003`

= 2.16 mol

Mass of carbon = moles carbon × molar mass carbon

= (2.16 mol) × (12.01 g/mol)

= 25.9 g

Thus, we can conclude that 25.9 g of carbon is expected in the sample.