Chemistry, 03.08.2019 05:30 krystlemiller4307

Acombustion analysis of 5.214 g of a compound yields 5.34 g co 2 , 1.09 g h 2 o, and 1.70 g n 2 . if the molar mass of the compound is 129.1 g/mol, what is the chemical formula of the compound?

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Let the formula of compound be $C_{a}H_{b}O_{c}N_{d}$ . The mass and molar mass of compound is 5.214 g and 129.1 g/mol respectively.

The combustion of compound gives 5.34 g of $CO_{2}$ , 1.09 g of $H_{2}O$ and 1.70 g of $N_{2}$ . First number of moles of carbon, hydrogen, oxygen and nitrogen to compare the molar ratio.

Calculation for number of moles:

For number of moles of C, first calculate number of mole of $CO_{2}$ :

$n=\frac{m}{M}$

Here, m is mass and M is molar mass.

Molar mass of $CO_{2}$ is 44.01 g/mol thus,

$n=\frac{5.34 g}{44.01 g/mol}=0.1213 mol$

Since, 1 mol of $CO_{2}$ have 1 mole of C thus, number of C will be 0.1213 mol.

Or, $n_{C}=0.1213 mol$

Convert this into mass as follows:

$m=n\times M$

Molar mass of C is 12 g/mol thus,

$m_{C}=0.1213 mol\times 12 g/mol=1.4556 g$

For number of moles of H, first calculate the number of moles of $H_{2}O$ :

$n=\frac{m}{M}$

Molar mass of $H_{2}O$ is 18 g/mol thus,

$n=\frac{1.09 g}{18 g/mol}=0.060 mol$

Since, 1 mol of $H_{2}O$ have 2 mole of H thus, number of H will be 2×0.060 mol=0.12 mol.

Or, $n_{H}=0.12 mol$

Convert this into mass as follows:

$m=n\times M$

Molar mass of H is 1 g/mol thus,

$m_{H}=0.12 mol\times 1 g/mol=0.12 g$

For number of moles of N, first calculate the number of moles of $N_{2}$ :

$n=\frac{m}{M}$

Molar mass of $N_{2}$ is 28 g/mol thus,

$n=\frac{1.70 g}{28 g/mol}=0.060 mol$

Since, 1 mol of $N_{2}$ have 2 mole of N thus, number of N will be 2×0.060 mol=0.12 mol.

Or, $n_{N}=0.12 mol$

Convert this into mass as follows:

$m=n\times M$

Molar mass of N is 14 g/mol thus,

$m_{N}=0.12 mol\times 14 g/mol=1.68 g$

Since, mass of compound is 5.214 g thus, mass of oxygen will be:

$m_{O}=m_{compound}-m_{C}-m_{H}-m_{N}=(5.214-1.4556-0.12-1.68)g=1.9584 g$

Molar mass of oxygen is 16 g/mol thus, number of moles of oxygen will be:

$n_{O}=\frac{1.9583 g}{16 g/mol}=0.1224 mol$

The ratio of number of moles of C, H,O and N will be:

C:H:O:N=0.1213:0.12:0.1224:0.12=1:1:1:1

Thus, empirical formula of compound will be CHON.

According to above formula molar mass of compound will be 43 g/mol

Now, according to chemical formula, the molar mass is 129.1 g/mol taking the ratio:

$x=\frac{129.1}{43}\approx 3$

Thus, chemical formula will be $3\times CHON=C_{3}H_{3}O_{3}N_{3}$

Therefore, chemical formula of compound is $C_{3}H_{3}O_{3}N_{3}$ .

Answer from: Quest

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the atomic number of carbon is six, which means that a carbon atom has six protons. carbon has three naturally occurring isotopes: carbon-12, carbon-13, and carbon-14. which of these statements are true about carbon and its isotopes? select all that appl

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