What is the molar heat of the formation of sodium aside?
The molar heat of formation of sodium (Na) is the amount of heat released or absorbed when one mole of sodium is formed from its elemental components (in their standard states) in their standard states under standard conditions (25 degrees Celsius and 1 atmospheric pressure).
The molar heat of formation of sodium is -240.1 kJ/mol, indicating that heat is released when sodium is formed.
The molar heat of formation of sodium chloride (NaCl) can be determined by using the Hess's law and the known molar heats of formation of the reactants and products involved. Here are the steps to calculate the molar heat of formation of sodium chloride:
Step 1: Write the balanced chemical equation for the formation of sodium chloride. The reaction takes place between solid sodium metal (Na) and gaseous chlorine (Cl2) to form solid sodium chloride (NaCl). The balanced equation is:
2 Na(s) + Cl2(g) -> 2 NaCl(s)
Step 2: Determine the molar heats of formation of the reactants and products. The molar heat of formation of sodium (ΔHf°[Na]) is 0 kJ/mol since it is in its standard state. The molar heat of formation of chlorine (ΔHf°[Cl2]) is 0 kJ/mol as well, as it exists as a diatomic gas in its standard state. The molar heat of formation of sodium chloride (ΔHf°[NaCl]) is -411 kJ/mol, which is an experimental value.
Step 3: Apply Hess's law, which states that the total enthalpy change of a reaction is independent of the pathway taken. In this case, we will consider two fictitious reactions to calculate the molar heat of formation of sodium chloride:
a) Na(s) + 1/2 Cl2(g) -> NaCl(s) ΔH1
b) Cl2(g) -> 2 NaCl(s) ΔH2
Step 4: Subtract the enthalpy change of reaction a) from the enthalpy change of reaction b) to obtain the molar heat of formation of sodium chloride. Mathematically, it can be expressed as:
ΔH2 - ΔH1 = ΔHf°[NaCl]
ΔH2 - 0 = -411 kJ/mol
ΔH2 = -411 kJ/mol
Therefore, the molar heat of formation of sodium chloride (NaCl) is -411 kJ/mol.
Note: The molar heat of formation values used in this explanation are approximate and may vary slightly depending on the source.
The molar heat of formation of sodium chloride refers to the amount of heat energy absorbed or released when one mole of sodium chloride is formed from its individual elements, sodium (Na) and chlorine (Cl2), under standard conditions (25 degrees Celsius and 1 atmosphere of pressure). To determine the molar heat of formation of sodium chloride, you can follow these steps:
1. Write the balanced chemical equation: The formation of sodium chloride can be represented by the equation:
Na (s) + 1/2 Cl2 (g) -> NaCl (s)
2. Calculate the enthalpy of formation (ΔH): The enthalpy of formation can be obtained by subtracting the enthalpies of the reactants from the enthalpy of the product. The standard enthalpy of formation of sodium (Na) is 0 kJ/mol, while the standard enthalpy of formation of chlorine gas (Cl2) is 0 kJ/mol. The standard enthalpy of formation of sodium chloride (NaCl) is -411 kJ/mol.
ΔH = Σ(H products) - Σ(H reactants)
ΔH = (-411 kJ/mol) - [0 kJ/mol + 0 kJ/mol]
ΔH = -411 kJ/mol
Therefore, the molar heat of formation of sodium chloride is -411 kJ/mol. Please note that this value can vary slightly depending on the specific reference or source used for the standard enthalpy values.