An unknown compound of mass 10.7696 g containing carbon, hydrogen and oxygen was combusted in oxygen producing CO2 (29.5747 g) and H2O (12.1068 g). Caluculate the mass of oxygen produced? (Atomic masses of C-12.011g/mol; O-15.999 g/mol; H-1.008 g/mol).
1.509 g
1.3438
0.672 g
8.071 g
We can find the mass of carbon and hydrogen in the unknown compound by subtracting the mass of CO2 and H2O produced from the initial mass of the compound:
Mass of carbon = mass of CO2 produced = 29.5747 g
Mass of hydrogen = mass of H2O produced = 12.1068 g
To find the mass of oxygen produced, we can use the law of conservation of mass, which states that the total mass of reactants is equal to the total mass of products. This means that the total mass of carbon, hydrogen and oxygen in the unknown compound is equal to the total mass of CO2 and H2O produced:
Mass of unknown compound = mass of carbon + mass of hydrogen + mass of oxygen
10.7696 g = 29.5747 g (mass of CO2) + 12.1068 g (mass of H2O) + mass of oxygen
Mass of oxygen = 10.7696 g - 29.5747 g - 12.1068 g
Mass of oxygen = -30.9119 g
This result is clearly not possible, as we cannot have negative mass. Therefore, we must have made a mistake somewhere. Let's check our calculations:
Mass of carbon + Mass of hydrogen = 29.5747 g + 12.1068 g = 41.6815 g
This means that the mass of oxygen in the unknown compound is:
Mass of oxygen = Mass of unknown compound - (Mass of carbon + Mass of hydrogen)
Mass of oxygen = 10.7696 g - 41.6815 g
Mass of oxygen = -30.9119 g
Again, we have a negative result, so there must be an error in our calculations. Let's check the atomic masses:
C: 12.011 g/mol
H: 1.008 g/mol
O: 15.999 g/mol
We can see that the unknown compound has more carbon and hydrogen than oxygen. This means that there cannot be a negative mass of oxygen, so we must have made a mistake in our calculations. The correct mass of oxygen produced can be found using the following equation:
Mass of carbon in unknown compound = Mass of CO2 produced = 29.5747 g
Number of moles of carbon in unknown compound = Mass of carbon / Atomic mass of carbon = 29.5747 g / 12.011 g/mol = 2.4648 mol
Number of moles of oxygen produced = Number of moles of carbon = 2.4648 mol
Mass of oxygen produced = Number of moles of oxygen produced x Atomic mass of oxygen = 2.4648 mol x 15.999 g/mol = 39.423 g
Therefore, the mass of oxygen produced is 39.423 g, which is closest to option D: 8.071 g.
To calculate the mass of oxygen produced, we need to find the difference in mass before and after combustion.
Given:
Mass of CO2 produced = 29.5747 g
Mass of H2O produced = 12.1068 g
We can first calculate the total mass of carbon in the CO2 produced:
C (carbon) = 12.011 g/mol × (1 mol CO2 / 44.01 g CO2) × 29.5747 g CO2 = 8.0959 g
Next, we calculate the total mass of hydrogen in the H2O produced:
H (hydrogen) = 1.008 g/mol × (2 mol H2O / 18.015 g H2O) × 12.1068 g H2O = 1.3461 g
Now, we can calculate the total mass of carbon and hydrogen in the unknown compound:
Mass of C + H = 8.0959 g + 1.3461 g = 9.442 g
Finally, we can calculate the mass of oxygen in the unknown compound by subtracting the total mass of C + H from the total mass of the compound:
Mass of oxygen = 10.7696 g - 9.442 g = 1.3276 g
Therefore, the mass of oxygen produced is 1.3276 g.