5535kJ is the reaction that represents breaking all the bonds in gaseous benzene C6H6.
The equation for the reaction is C6H6 (g)--->6CH (g).
C6
the breaking down of elements into atoms. it is the energy required when 1 mole of a substance completely decomposes into its gaseous atoms i.e endothermic reaction, delta H is +ve meaning breaking bonds
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
The standard enthalpy for sodium sulphate is -1387kJ/mol.
The answer to this question will depend on what the substance that is reacting is. You will need to find the appropriate standard enthalpy value, which corresponds to the amount of enthalpy change when one mole of matter is transformed by a chemical reaction in standard conditions.
Enthalpy change of neutralisation is defined as the enthalpy change of a reaction where one mole of hydrogen ions reacts with one mole of hydroxide ions to form one mole of water under standard conditions of 1 atm, 298K (25 degree Celsius) and in the solutions containing 1 mol per dm3.
the heat released or absorbed in a reaction
the breaking down of elements into atoms. it is the energy required when 1 mole of a substance completely decomposes into its gaseous atoms i.e endothermic reaction, delta H is +ve meaning breaking bonds
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
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.
The standard enthalpy for sodium sulphate is -1387kJ/mol.
The answer to this question will depend on what the substance that is reacting is. You will need to find the appropriate standard enthalpy value, which corresponds to the amount of enthalpy change when one mole of matter is transformed by a chemical reaction in standard conditions.
Enthalpy change of neutralisation is defined as the enthalpy change of a reaction where one mole of hydrogen ions reacts with one mole of hydroxide ions to form one mole of water under standard conditions of 1 atm, 298K (25 degree Celsius) and in the solutions containing 1 mol per dm3.
i believe that standard enthalpy change of atomisation is the enthalpy change that takes place when one mole of gaseous atoms is formed from its elements under standard conditions(which includes breaking of bonds between atoms within molecules), while for sublimation it only involves the change of states (from solid to liquid) with no intramolecular bonds broken.
the standard enthalpy change of vaporization DHov is the enthalpy change when one mole of a substance is transformed into a gas enthalpy change is the term we use to describe the energy exchange that occurs with the surroundings at a constant temperature and pressure so to work it out, use the formula DH = cmDT DH - the enthalpy change c - the specific heat capacity of butanol (kJ kg-1 °C-1) m - the mass of butanol heated (kg) DT - the change in temperature of the butanol (°C) so there is no general enthalpy change of butanol, it depends on the factors above. the specific heat capacity of butanol, the mass of butanol heated, and the change in temperature of the butanol should be given to you in order to work the enthalpy change of vaporization of butanol if there is a rise in temperature, the reaction is exothermic and if there is a drop in temperature the reaction is endothermic. exothermic reactions have a negative enthalpy change, and therefore endothermic reactions have a positive enthalpy change. hope it helped (:
The reaction is exothermic; the standard enthalpy of formation for sodium chloride is -411,12 kJ/mol at 25 0C.
-6969 Kj/mol2
if there is an increase in the number of gas molecules , then ^S > 0