# Calc ∆Hf (kJ/mol) for C3H8 + 5 O2 -> 3 CO2 + 4 H2O

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• chrisisone
In summary, to determine the total enthalpy of the reactants and products, use the standard enthalpy of formation (∆Hf) values for each substance and multiply by the number of moles. Add these values together to get the total enthalpy. Record these values in Table C of the Student Worksheet.
chrisisone
Determine the total enthalpy of the reactants and the total enthalpy of the products. Record these values in Table C of the Student Worksheet.

I need to know the total number of products and reactants in ∆Hf (kJ/mol) The substances are:

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Based on the chemical equation provided, there are 2 reactants (C3H8 and O2) and 2 products (CO2 and H2O). To determine the total enthalpy of the reactants and products, you will need to use the standard enthalpy of formation (∆Hf) values for each substance. These values can be found in reference tables or online databases.

To calculate the total enthalpy of the reactants, you will need to multiply the number of moles of each substance by its respective ∆Hf value and then add them together. For example, for C3H8, the ∆Hf value is -103.8 kJ/mol, so the total enthalpy of the reactants would be: (1 mol C3H8)(-103.8 kJ/mol) + (5 mol O2)(0 kJ/mol) = -103.8 kJ.

Similarly, to calculate the total enthalpy of the products, you will need to multiply the number of moles of each substance by its respective ∆Hf value and then add them together. For CO2, the ∆Hf value is -393.5 kJ/mol, and for H2O, the ∆Hf value is -241.8 kJ/mol. So the total enthalpy of the products would be: (3 mol CO2)(-393.5 kJ/mol) + (4 mol H2O)(-241.8 kJ/mol) = -2028.7 kJ.

Remember to record these values in Table C of the Student Worksheet. Hope this helps!

## What is the meaning of "Calc ∆Hf (kJ/mol) for C3H8 + 5 O2 -> 3 CO2 + 4 H2O"?

This equation represents the change in enthalpy (heat energy) that occurs when one mole of C3H8 (propane) reacts with five moles of O2 (oxygen) to produce three moles of CO2 (carbon dioxide) and four moles of H2O (water).

## What is ∆Hf (kJ/mol)?

∆Hf (kJ/mol) stands for the change in enthalpy of formation per mole. It is a measure of the amount of heat energy released or absorbed when one mole of a substance is formed from its constituent elements in their standard states.

## How is ∆Hf (kJ/mol) calculated?

∆Hf (kJ/mol) is typically calculated using Hess's Law, which states that the total enthalpy change of a reaction is equal to the sum of the enthalpy changes of its individual steps. In this case, the enthalpy changes of the formation of CO2 and H2O are subtracted from the enthalpy change of the combustion of C3H8 to determine the ∆Hf (kJ/mol) for the overall reaction.

## What factors can affect ∆Hf (kJ/mol)?

The ∆Hf (kJ/mol) value for a substance can be affected by factors such as temperature, pressure, and the state of the reactants and products (solid, liquid, gas). It can also vary depending on the reference state used for the elements in the reaction.

## Why is ∆Hf (kJ/mol) important in chemistry?

∆Hf (kJ/mol) is an important concept in chemistry as it helps us to understand the energy changes that occur during chemical reactions. It can also be used to predict the feasibility and direction of a reaction, as well as to calculate the amount of heat energy released or absorbed during a reaction.

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