The hydrogen sulfide in a 79.168 g sample of crude petroleum was removed by distillation and collected in a solution of CdCl2. The precipitated CdS was then filtered, washed and ignited to create CdSO4. Calculate the percentage of H2S in the sample if 0.122 grams of CdSO4 was formed.
To calculate the percentage of H2S in the crude petroleum sample, you need to determine the relative amount of H2S compared to the amount of CdSO4 formed.
Let's break down the problem step by step:
1. Calculate the molar mass of CdSO4:
- Cd: 112.41 g/mol
- S: 32.07 g/mol
- Oxygen (from SO4): 16.00 g/mol
- CdSO4: 112.41 g/mol + 32.07 g/mol + 4 * (16.00 g/mol) = 208.41 g/mol
2. Calculate the moles of CdSO4 formed:
- Moles = mass / molar mass
- Moles of CdSO4 = 0.122 g / 208.41 g/mol
3. Calculate the moles of H2S:
- According to the balanced chemical equation, CdSO4 is formed from CdS and sulfuric acid (H2SO4) during the ignition process.
- The stoichiometry of the balanced chemical equation indicates that for every mole of CdS, one mole of H2S is produced.
- So, the moles of H2S in the sample are equal to the moles of CdSO4 formed.
4. Calculate the mass of H2S:
- Mass = moles x molar mass
- Mass of H2S = Moles of H2S x Molar mass of H2S
5. Calculate the percentage of H2S in the sample:
- Percentage = (Mass of H2S / Mass of the sample) x 100
Now, plug in the values into the formulas:
1. Molar mass of CdSO4 = 208.41 g/mol
2. Moles of CdSO4 = 0.122 g / 208.41 g/mol
3. Moles of H2S = Moles of CdSO4
4. Mass of H2S = Moles of H2S x Molar mass of H2S
5. Percentage of H2S = (Mass of H2S / Mass of the sample) x 100
Follow these steps, and you will get the percentage of H2S in the crude petroleum sample.