Calculate the heat released when 3.10 L of Cl2(g) with a density of 1.88 g/L reacts with an excess of sodium metal at 25°C and 1 atm to form sodium chloride
Write the equation and balance it.
Convert 3.10 L Cl2 to grams (using density), then to moles. Look up delta Hf for products and reactants, then
delta Hrxn = (delta Hproducts)-(delta Hreactants).
Then why am I calculating the moles if I just need to look up the Change in H for products and reactants...that isn't going to give me the heat released. What formulas do I need to use?
To calculate the heat released in the given reaction, we need to determine the moles of chlorine gas (Cl2) that react with the excess sodium metal. Then we can use the balanced chemical equation and the enthalpy change of the reaction to calculate the heat released.
1. Determine the moles of Cl2:
We are given the volume of Cl2 gas (3.10 L) and its density (1.88 g/L). To find the moles, we need to use the molar mass of Cl2, which is 70.90 g/mol.
Moles of Cl2 = volume of Cl2 gas (L) × density of Cl2 (g/L) / molar mass of Cl2 (g/mol)
= 3.10 L × 1.88 g/L / 70.90 g/mol
2. Calculate the moles of sodium chloride (NaCl) formed:
From the balanced chemical equation for the reaction, we know that 1 mole of Cl2 reacts with 2 moles of Na to form 2 moles of NaCl. Therefore, the number of moles of Cl2 is also the number of moles of NaCl.
Moles of NaCl = Moles of Cl2
3. Use the enthalpy change of the reaction to calculate the heat released:
The enthalpy change of the reaction can be found in a thermodynamic table or given in the problem statement. Let's assume it is ΔH = -200 kJ/mol (where the negative sign indicates heat release).
Heat released = Moles of NaCl × ΔH
= Moles of Cl2 × ΔH
Plug in the calculated values to obtain the final answer.
Note: To solve this problem accurately, it is always recommended to use the actual enthalpy change value if available, as it may differ from the assumed value provided in this example.