A propane barbeque is used to heat up 400g of water in an aluminum pot until it is boiling. Using the following information, calculate the molar enthalpy of propane. You can assume the temperature of the water and the temperature of the aluminum pot are always the same.
Initial water temperature=25 degrees C
Mass of propane burned=300g
Heat capacity of aluminum=0.900j/g degrees C
Mass of aluminum pot=150g
anyone have it?
To calculate the molar enthalpy of propane, we need to follow these steps:
Step 1: Calculate the heat absorbed by the water.
The heat absorbed by the water can be calculated using the equation:
Q = m * c * ΔT
where Q is the heat absorbed, m is the mass of the water, c is the heat capacity of water (which is approximately 4.18 J/g°C), and ΔT is the change in temperature.
Given:
- Initial water temperature = 25°C
- Final temperature (boiling point of water) = 100°C
- Mass of water = 400g (m)
Using the equation:
Q = 400g * 4.18 J/g°C * (100°C - 25°C)
Q = 400g * 4.18 J/g°C * 75°C
Q = 125400 J
Step 2: Calculate the heat absorbed by the aluminum pot.
The heat absorbed by the aluminum pot can be calculated using the same equation as above:
Q = m * c * ΔT
Given:
- Initial temperature of aluminum pot = 25°C
- Final temperature of aluminum pot (assuming it reaches boiling point) = 100°C
- Mass of aluminum pot = 150g (m)
- Heat capacity of aluminum = 0.900 J/g°C (c)
Using the equation:
Q = 150g * 0.900 J/g°C * (100°C - 25°C)
Q = 150g * 0.900 J/g°C * 75°C
Q = 10125 J
Step 3: Calculate the total heat absorbed.
The total heat absorbed is the sum of the heat absorbed by the water and the heat absorbed by the aluminum pot.
Total Q = Q_water + Q_aluminum
Total Q = 125400 J + 10125 J
Total Q = 135525 J
Step 4: Calculate the number of moles of propane burned.
The number of moles of propane can be calculated using its molar mass. The molar mass of propane (C3H8) is approximately 44 g/mol.
Given:
- Mass of propane burned = 300g
Using the equation:
Number of moles = mass / molar mass
Number of moles = 300g / 44 g/mol
Number of moles = 6.82 mol
Step 5: Calculate the molar enthalpy of propane.
The molar enthalpy of propane can be calculated by dividing the total heat absorbed (Q) by the number of moles (n).
Molar enthalpy = Q / n
Molar enthalpy = 135525 J / 6.82 mol
The molar enthalpy of propane is approximately 19889 J/mol.