delta H and delta U
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Re: delta H and delta U
U is a measure of internal energy, which is basically all of the energy of a system. Energy can be transferred into a system through heating (q) or doing work on a system (w). In thermochemistry, ΔH is the difference in enthalpy between the products and the reactants; it is basically the heat that is absorbed or released by a reaction. At constant pressure, ΔH is the same as q.
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Re: delta H and delta U
Delta U involves both work and heat being exchanged between the system and the surroundings. Delta H refers to the enthalpy transfer of the products minus that of the reactants to get the total change in enthalpy. Often we will be provided values of delta H for specific products and reactants and be asked to calculate the Delta H for a reaction given the reaction is in standard conditions. This would be done by subtracting delta H of the reactants from the products.
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Re: delta H and delta U
Put simply, ∆H is difference in enthalpy (which is difference in heat for constant pressure), and ∆U is difference in internal energy, which factors in heat and work.
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Re: delta H and delta U
Delta H is the change in enthalpy and Delta U is the change in internal energy. The change in internal energy is calculated by adding heat and work. Heat is calculated by the equation, q=(m)(C)(deltaT) or q=(n)(C)(deltaT). And work is calculated with the equation w=(-n)(R)(T)ln(V2/V2) for a change in pressure or w=(-Pex)(delta V) when pressure is constant. At constant pressure, Delta H is equal to q.
Hope this helps!
Hope this helps!
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Re: delta H and delta U
Delta H refers to the change in enthalpy or the difference of the heat of a system, while delta U refers to the change in the internal energy of a system. You can find how much heat a sample absorbed or released by solving for q in the equation q = mc(delta T), where c is the specific heat.
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Re: delta H and delta U
Delta U is the change in internal energy. In an isothermal reaction, from beginning to end, Delta U would be equal to zero. Delta H is the change in enthalpy, so when Delta H is negative, then the reaction is exothermic.
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Re: delta H and delta U
Delta H is the change in enthalpy, and Delta U is the change in the internal energy of a system. To calculate Delta H, we focus on the products and reactants, and the change in enthalpy between them, and how much is either absorbed or released by the system. To calculate Delta U, you add work (w) and heat (q). To get heat (q), this is where we would use q = mCdeltaT or q = nCdeltaT, where the C is a constant, and usually depends on the substance.
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Re: delta H and delta U
The difference between delta H and Delta U is that delta H is the difference in enthalpy while delta U is the difference in internal energy. At constant pressure, delta H is equal to q. q can be calculated in q=(m)(c)(deltaT) or q=(n)(c)(delta T). You can calculate delta U by adding the heat and work and you can find work with w=(-n)(R)(T)ln(V2/v1) if there's a change in pressure.
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