A mixture containing 15 g of carbon and 25 g of oxygen is sealed in a flask. The total mass of the system is 140 g. The flask is then heated to cause the carbon and oxygen to react. The sealed flask is then weighed. What is the final weight of the system?
To find the final weight of the system, we need to determine the mass of the products formed from the reaction between carbon and oxygen.
The reaction between carbon (C) and oxygen (O₂) produces carbon dioxide (CO₂).
To calculate the mass of carbon dioxide produced, we need to determine the limiting reactant in the reaction using the concept of the law of conservation of mass.
1. Calculate the moles of carbon (C):
The molar mass of carbon is 12.01 g/mol.
Moles of carbon = Mass of carbon / Molar mass of carbon
= 15 g / 12.01 g/mol
= 1.248 mol (rounded to three decimal places)
2. Calculate the moles of oxygen (O₂):
The molar mass of oxygen is 16.00 g/mol.
Moles of oxygen = Mass of oxygen / Molar mass of oxygen
= 25 g / 16.00 g/mol
= 1.563 mol (rounded to three decimal places)
3. Determine the limiting reactant:
The reactant with fewer moles is the limiting reactant. In this case, carbon (C) has fewer moles, so it is the limiting reactant.
4. Calculate the moles of carbon dioxide (CO₂) produced:
From the balanced equation:
2C + O₂ -> 2CO₂
We can see that 2 moles of carbon dioxide are produced for every 1 mole of carbon reacted.
Therefore, the moles of carbon dioxide produced are 2 * Moles of carbon
Moles of carbon dioxide = 2 * 1.248 mol
= 2.496 mol (rounded to three decimal places)
5. Calculate the mass of carbon dioxide produced:
The molar mass of carbon dioxide (CO₂) is 44.01 g/mol.
Mass of carbon dioxide = Moles of carbon dioxide * Molar mass of carbon dioxide
= 2.496 mol * 44.01 g/mol
= 109.96 g (rounded to two decimal places)
6. Calculate the final weight of the system:
Since the flask is a closed system, the mass of the reactants and products remains constant.
Final weight of the system = Initial weight of the system + Mass of carbon dioxide produced
= 140 g + 109.96 g
= 249.96 g (rounded to two decimal places)
Therefore, the final weight of the system is 249.96 g.
To determine the final weight of the system after the reaction, we need to consider the law of conservation of mass, which states that mass cannot be created or destroyed during a chemical reaction.
First, we need to calculate the initial total mass of the carbon and oxygen in the mixture:
Initial total mass = Mass of carbon + Mass of oxygen
Initial total mass = 15 g + 25 g
Initial total mass = 40 g
According to the conservation of mass, the total mass of the system before and after the reaction should be the same. Therefore, the final weight of the system is also 140 g.
Thus, the final weight of the system remains unchanged at 140 g after the reaction.
Conservation of mass:
40 grams