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The change in enthalpy that accompanies the formation of a compound from its elements?
Wiki User
∙ 10y ago
The energy change that happens when a substance forms from its elements (APEX)
Wilburn Weissnat
Wiki User
∙ 10y agoHeat of formation
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What best describe the enthalpy of formation of a substance?
The enthalpy of formation of a substance is the amount of energy that was put in or evolved from the making of that substance from the individual elements.
Equation for the heat of formation of carbon disulphide?
C + 2S -> CS2 Enthalpy of formation is the change in enthalpy for the formation of a substance from its elements.
What is the difference of enthalpy of formation and the enthalpy of combustion?
Enthalpy of combusion is energy change when reacting with oxygen. Enthalpy of formation is energy change when forming a compound. But some enthalpies can be equal.ex-Combusion of H2 and formation of H2O is equal
What is an endothermic compound and what is an exothermic compound?
Compounds are not generally considered endothermic or exothermic. These terms refer to processes. So, the process of formation, or the process of decomposition, would be an endothermic process or an exothermic process.
What is the basic difference between enthalpy of formation?
Standard Heat (Enthalpy) of Formation, Hfo, of any compound is the enthalpy change of the reaction by which it is formed from its elements, reactants and products all being in a given standard state.By definition, the standard enthalpy (heat) of formation of an element in its standard state is zero, Hfo = 0.Standard Molar Enthalpy (Heat) of Formation, Hmo, of a compound is the enthalpy change that occurs when one mole of the compound in its standard state is formed from its elements in their standard states.Standard Enthalpy (Heat) of Reaction, Ho, is the difference between the standard enthalpies (heats) of formation of the products and the reactants.Ho(reaction) = the sum of the enthalpy (heat) of formation of products - the sum of the enthalpy (heat) of formation of reactants: Ho(reaction) = Hof(products) - Hof(reactants)To calculate an Enthalpy (Heat) of Reaction:Write the balanced chemical equation for the reaction Remember to include the state (solid, liquid, gas, or aqueous) for each reactant and product.Write the general equation for calculating the enthalpy (heat) of reaction: Ho(reaction) = Hof(products) - Hof(reactants)Substitute the values for the enthalpy (heat) of formation of each product and reactant into the equation. Remember, if there are 2 moles of a reactant or product, you will need to multiply the enthalpy term by 2, if molar enthalpies (heats) of formation are used.Standard Enthalpy (Heat) of FormationExample: Standard Enthalpy (Heat) of Formation of WaterThe standard enthalpy (heat) of formation for liquid water at 298K (25o) is -286 kJ mol-1. This means that 286 kJ of energy is released when liquid water, H2O(l), is produced from its elements, hydrogen and oxygen, in their standard states, ie, H2(g) and O2(g).This reaction is written as:H2(g) + ½O2(g) -----> H2O(l) Hfo = -286 kJ mol-1The standard enthalpy (heat) of formation of water vapour at 298K (25o) is -242 kJ mol-1.This means that 242 kJ of energy is released when gaseous water (water vapour), H2O(g), is produced from its elements, hydrogen and oxygen, in their standard states, ie, H2(g) and O2(g).This reaction is written as:H2(g) + ½O2(g) -----> H2O(g) Hfo = -242 kJ mol-1
What best describe the enthalpy of formation of a substance?
The enthalpy of formation of a substance is the amount of energy that was put in or evolved from the making of that substance from the individual elements.
What is the heat released during the synthesis of one mole of compound from its elements?
Molar heat (or enthalpy) of formation.
Equation for the heat of formation of carbon disulphide?
C + 2S -> CS2 Enthalpy of formation is the change in enthalpy for the formation of a substance from its elements.
What is the difference of enthalpy of formation and the enthalpy of combustion?
Enthalpy of combusion is energy change when reacting with oxygen. Enthalpy of formation is energy change when forming a compound. But some enthalpies can be equal.ex-Combusion of H2 and formation of H2O is equal
What is an endothermic compound and what is an exothermic compound?
Compounds are not generally considered endothermic or exothermic. These terms refer to processes. So, the process of formation, or the process of decomposition, would be an endothermic process or an exothermic process.
What is the basic difference between enthalpy of formation?
Standard Heat (Enthalpy) of Formation, Hfo, of any compound is the enthalpy change of the reaction by which it is formed from its elements, reactants and products all being in a given standard state.By definition, the standard enthalpy (heat) of formation of an element in its standard state is zero, Hfo = 0.Standard Molar Enthalpy (Heat) of Formation, Hmo, of a compound is the enthalpy change that occurs when one mole of the compound in its standard state is formed from its elements in their standard states.Standard Enthalpy (Heat) of Reaction, Ho, is the difference between the standard enthalpies (heats) of formation of the products and the reactants.Ho(reaction) = the sum of the enthalpy (heat) of formation of products - the sum of the enthalpy (heat) of formation of reactants: Ho(reaction) = Hof(products) - Hof(reactants)To calculate an Enthalpy (Heat) of Reaction:Write the balanced chemical equation for the reaction Remember to include the state (solid, liquid, gas, or aqueous) for each reactant and product.Write the general equation for calculating the enthalpy (heat) of reaction: Ho(reaction) = Hof(products) - Hof(reactants)Substitute the values for the enthalpy (heat) of formation of each product and reactant into the equation. Remember, if there are 2 moles of a reactant or product, you will need to multiply the enthalpy term by 2, if molar enthalpies (heats) of formation are used.Standard Enthalpy (Heat) of FormationExample: Standard Enthalpy (Heat) of Formation of WaterThe standard enthalpy (heat) of formation for liquid water at 298K (25o) is -286 kJ mol-1. This means that 286 kJ of energy is released when liquid water, H2O(l), is produced from its elements, hydrogen and oxygen, in their standard states, ie, H2(g) and O2(g).This reaction is written as:H2(g) + ½O2(g) -----> H2O(l) Hfo = -286 kJ mol-1The standard enthalpy (heat) of formation of water vapour at 298K (25o) is -242 kJ mol-1.This means that 242 kJ of energy is released when gaseous water (water vapour), H2O(g), is produced from its elements, hydrogen and oxygen, in their standard states, ie, H2(g) and O2(g).This reaction is written as:H2(g) + ½O2(g) -----> H2O(g) Hfo = -242 kJ mol-1
What is the purpose of defining the standard enthalpies of formation?
The standard enthalpy of formation is a measure of the energy released or consumed when one mole of a substance is created under standard conditions from its pure elements. A triangle is a change in enthalpy. A degree signifies that it's a standard enthalpy change. A f is a reaction from a substance that's formed from its elements.
What is the standard enthalpy of formation of hydrogen bromide?
[from wikipedia] The standard enthalpy of formation"standard heat of formation" of a compound is the change of enthalpy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually 298.15 K or 25 degrees Celsius). Its symbol is ΔHfO.
How does lattice energy differs from bond enthalpy?
Bond enthalpy is the energy required to break a chemical bond whereas lattice energy is the enthalpy of formation of one mole of an ionic compound from gaseus ions under standard conditions.
What best describes the enthalpy of formation of a substance?
The energy change that happens when a substance forms from its elements (APEX)
Why does oxygen gas not have an enthalpy of formation but ozone does?
Ozone gas has enthalpy of formation. It is due to the high altitude.
What does the negative sign on the value of an enthalpy of formation indicate?
A negative enthalpy of formation indicates that energy is evolved.
