Question

the standard molar heat of formation of ethane ch2 and what are respectively -21.194 and 168.3 the standard molar heat of combustion of ethane will be

Answer 1

The standard molar heat of combustion of ethane is -389.5 kJ/mol.

Step-by-step explanation:

The standard molar heat of combustion of a substance is the enthalpy change for the complete combustion of one mole of the substance under standard conditions (25°C and 1 atm pressure). The combustion of ethane can be represented by the following equation:

`C_2H_6(g) + 3.5O_2(g)` →
`2CO_2(g) + 3H_2O(g)`

The standard molar enthalpy change for this reaction is -389.5 kJ/mol. This means that 389.5 kJ of heat are released when one mole of ethane is burned completely under standard conditions.

The standard molar heat of combustion of a substance can be calculated using the following equation:

ΔH°combustion = ΣΔH°f(products) - ΣΔH°f(reactants)

where:

ΔH°combustion is the standard molar heat of combustion (kJ/mol)

ΔH°f is the standard molar heat of formation (kJ/mol)

The standard molar heats of formation of ethane,
`CO_2`, and
`H_2O` are -21.1 kJ/mol, -393.5 kJ/mol, and -285.8 kJ/mol, respectively. Plugging these values into the equation, we get:

ΔH°combustion = (2 × -393.5 kJ/mol) + (3 × -285.8 kJ/mol) - (-21.1 kJ/mol) = -389.5 kJ/mol

Therefore, the standard molar heat of combustion of ethane is -389.5 kJ/mol.