How much heat is released when a mixture containing 12.6 g CS2 and 13.2 g Cl2 reacts by the following equation?
CS2(g) + 3 Cl2(g) → S2Cl2(g) + CCl4(g)
ΔH° = −230. kJ
To calculate the amount of heat released in a chemical reaction, you need to use the concept of stoichiometry and the given reaction equation and enthalpy change value (ΔH°).
Here's how you can calculate the heat released:
1. Convert the given masses of CS2 and Cl2 into moles. To do this, divide the given mass of each substance by their respective molar masses.
- Molar mass of CS2 (carbon disulfide) = 76.14 g/mol
- Molar mass of Cl2 (chlorine) = 70.91 g/mol
Moles of CS2 = 12.6 g / 76.14 g/mol
Moles of Cl2 = 13.2 g / 70.91 g/mol
2. Determine the limiting reactant. The limiting reactant is the one that is completely consumed in the reaction, limiting the amount of product that can be formed. To find the limiting reactant, compare the number of moles of each reactant and their stoichiometric coefficients in the balanced equation.
From the balanced equation, the stoichiometric ratio of CS2 to Cl2 is 1:3. So, if CS2 reacts with 1 mole of Cl2, it will require 3 moles of Cl2.
Compare the number of moles:
Moles of CS2 = 12.6 g / 76.14 g/mol
Moles of Cl2 = 13.2 g / 70.91 g/mol
Convert the moles of Cl2 required for the reaction with the defined moles of CS2:
Moles of Cl2 required = Moles of CS2 * (3 moles Cl2 / 1 mole CS2)
Compare this value to the actual moles of Cl2 available. If the moles of Cl2 required are greater than the moles of Cl2 available, then Cl2 is the limiting reactant. Otherwise, if the moles of Cl2 required are less than the moles of Cl2 available, then CS2 is the limiting reactant.
3. Calculate the moles of product formed using the stoichiometry of the reaction. The stoichiometry gives the ratio of reactants to products in moles.
For the balanced equation: CS2(g) + 3 Cl2(g) → S2Cl2(g) + CCl4(g)
Moles of limiting reactant (either CS2 or Cl2) * (moles of product / moles of limiting reactant)
4. Multiply the moles of product formed by the enthalpy change (ΔH°) per mole of the reaction. The ΔH° value is -230 kJ/mol for the given reaction.
Moles of product * ΔH°
This will give the heat released in kJ.
Remember to keep track of units and follow the correct stoichiometric ratios when performing the calculations.
To calculate the amount of heat released in the reaction, we will follow these steps:
Step 1: Calculate the moles of CS2 and Cl2 using their molar masses.
Step 2: Determine the limiting reactant.
Step 3: Use the stoichiometric coefficients from the balanced equation to find the moles of S2Cl2 and CCl4 formed.
Step 4: Calculate the heat released using the stoichiometry and the given enthalpy change.
Let's start with step 1:
Step 1: Calculate the moles of CS2 and Cl2
Molar mass of CS2 = 12.01 g/mol (C) + 32.07 g/mol (S) = 44.08 g/mol
Moles of CS2 = 12.6 g / 44.08 g/mol = 0.285 mol
Molar mass of Cl2 = 2 x 35.45 g/mol = 70.90 g/mol
Moles of Cl2 = 13.2 g / 70.90 g/mol = 0.186 mol
Step 2: Determine the limiting reactant
To determine the limiting reactant, we compare the mole ratios of CS2 and Cl2 in the balanced equation.
From the balanced equation:
1 mol CS2 reacts with 3 mol Cl2
Mole ratio of CS2 to Cl2:
0.285 mol CS2 / 1 = 0.285
0.186 mol Cl2 / 3 = 0.062
The limiting reactant is Cl2 because it is completely consumed before all the CS2 is used.
Step 3: Use the stoichiometric coefficients to find the moles of S2Cl2 and CCl4 formed.
From the balanced equation:
1 mol CS2 reacts to form 1 mol S2Cl2
3 mol Cl2 reacts to form 1 mol CCl4
Since Cl2 is the limiting reactant, we consider its mole ratio:
0.186 mol Cl2 * (1 mol CCl4 / 3 mol Cl2) = 0.062 mol CCl4
The mole ratio of CS2 to S2Cl2:
0.285 mol CS2 * (1 mol S2Cl2 / 1 mol CS2) = 0.285 mol S2Cl2
Step 4: Calculate the heat released using stoichiometry and given enthalpy change.
According to the equation, when 1 mol of the reaction occurs, it releases -230 kJ of heat.
Using the mole ratio from step 3, we can calculate the heat released.
Heat released = moles of limiting reactant * ΔH°
= 0.062 mol CCl4 * -230 kJ/mol
= -14.06 kJ
Therefore, when the mixture containing 12.6 g CS2 and 13.2 g Cl2 reacts, it releases approximately 14.06 kJ of heat.