Acetylene(C2H2) torches are used in welding.
How much heat (in kJ) evolves when 2.0L of C2H2 (d=1.0967kg/m3) is mixed with a stoichiometric amount of oxygen gas? The combustion reaction is C2H2(g)+52O2(g)→2CO2(g)+H2O(l), ΔH∘=−1299.5kJ
Convert 2.0 L acetylene to grams using density.
q = heat evolved = 1299.5 x (g C2H2/26) = ?
Well, that's quite a fiery situation we have here! Let's find out how much heat will be generated when acetylene meets its oxygen match.
First, we need to determine how many moles of acetylene we have. We can do this by using the density and molar mass of acetylene.
The molar mass of C2H2 is approximately 26 g/mol (2 * 12.01 g/mol + 2 * 1.01 g/mol).
To find the mass of acetylene, we can multiply the density (1.0967 kg/m3) by the volume (2.0 L), keeping in mind that 1 L = 1 dm3. So, the mass of acetylene is 1.0967 kg/m3 * 2.0 dm3 = 2.1934 kg.
Next, we need to convert the mass of acetylene to moles. Since the molar mass of C2H2 is 26 g/mol, we have 2.1934 kg * (1000 g/kg) / (26 g/mol) = 84.36 mol of C2H2.
Now, we know that the reaction is stoichiometric, which means that 1 mole of acetylene reacts with 52 moles of oxygen gas. So, we have 84.36 mol of C2H2, which means we'll need 84.36 mol * 52 mol O2/mol C2H2 = 4385.92 mol of O2.
Finally, we can calculate the amount of heat evolved using the enthalpy change of the reaction (-1299.5 kJ/mol). We multiply this value by the number of moles of acetylene (84.36 mol) and then divide by 1000 to convert the result to kJ:
Heat evolved = -1299.5 kJ/mol * 84.36 mol / 1000 = -109548.18 kJ.
So, when 2.0 L of acetylene is mixed with a stoichiometric amount of oxygen gas, approximately -109548.18 kJ of heat is evolved. That's one hot date between C2H2 and O2!
To calculate the heat evolved when 2.0L of C2H2 is mixed with a stoichiometric amount of oxygen gas, we can follow these steps:
Step 1: Calculate the mass of C2H2 gas:
Given:
Density of C2H2 (d) = 1.0967 kg/m^3
Volume of C2H2 (V) = 2.0 L
Firstly, we need to convert the volume of C2H2 to the mass of C2H2 using its density:
Mass = Density * Volume
Mass = 1.0967 kg/m^3 * 2.0 L
Step 2: Calculate the heat evolved using stoichiometry:
Given:
Balanced equation: C2H2(g) + 5O2(g) → 2CO2(g) + H2O(l)
Enthalpy change: ΔH° = -1299.5 kJ
The stoichiometry of the reaction tells us that for every 1 mole of C2H2 that reacts, 5 moles of O2 react.
We can use the ideal gas law to convert the mass of C2H2 to moles:
Molar mass of C2H2 (M) = 2 * Atomic mass of C + 2 * Atomic mass of H
Molar mass of C2H2 ≈ 2 * 12 g/mol + 2 * 1 g/mol
Moles = Mass / Molar mass
Now, we can determine the moles of C2H2 reacted.
Next, using the stoichiometry of the reaction, we can calculate the moles of O2 reacted, which will be 5 times the moles of C2H2.
Finally, we can calculate the heat evolved using the enthalpy change (ΔH°) and the moles of C2H2 reacted:
Heat evolved = ΔH° * Moles of C2H2 reacted
Following these steps, you can calculate the heat evolved in kJ.
To calculate the heat evolved during the combustion of acetylene with oxygen, we first need to determine the number of moles of acetylene (C2H2) and oxygen (O2) involved in the reaction. Then, we can use the stoichiometry of the reaction and the enthalpy change of the reaction to calculate the heat evolved.
1. Convert the volume of acetylene gas (2.0 L) to moles:
- To do this, we need to know the molar mass of acetylene, which is the sum of the atomic masses of its constituent elements.
- Carbon (C): 12.01 g/mol
- Hydrogen (H): 1.01 g/mol
- Acetylene (C2H2): (2 × 12.01 g/mol) + (2 × 1.01 g/mol) = 26.04 g/mol
- Density of acetylene (d = 1.0967 kg/m3) can be converted to grams per liter (g/L) by multiplying by 1000: d = 1.0967 kg/m3 × 1000 g/kg = 1096.7 g/L
- Number of moles of acetylene gas: (2.0 L) × (1096.7 g/L) / (26.04 g/mol) = 83.66 mol
2. Determine the number of moles of oxygen gas.
- The reaction is stoichiometric, meaning that the number of moles of oxygen gas is directly proportional to the number of moles of acetylene gas.
- From the balanced equation, the stoichiometric ratio between acetylene and oxygen is 1:52.
- Number of moles of oxygen gas: 83.66 mol × 52 = 4348.32 mol
3. Use the balanced equation and enthalpy change to calculate the heat evolved.
- From the balanced equation: C2H2(g) + 5/2O2(g) → 2CO2(g) + H2O(l)
- Enthalpy change (ΔH°) for the reaction: -1299.5 kJ
- We can use the balanced equation coefficients and the ΔH° value to calculate the heat evolved.
- Heat evolved (in kJ) = (-1299.5 kJ / 1 mol) × (83.66 mol / 1 mol) = -108,574.67 kJ
Therefore, the heat evolved when 2.0 L of C2H2 is mixed with a stoichiometric amount of oxygen gas is approximately -108,574.67 kJ. The negative sign indicates that the reaction is exothermic, releasing heat.