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### Delta H v. q

Posted: Thu Jan 30, 2020 9:26 am
What is the difference between delta H and q?

### Re: Delta H v. q

Posted: Thu Jan 30, 2020 9:53 am
I believe that q is simply the heat that can be measured in a transfer. Enthalpy (delta H) is the total heat content in a system. It is energy, kind of like its potential energy RELATING to heat.

### Re: Delta H v. q

Posted: Thu Jan 30, 2020 11:24 am
Do you know why or how delta H is equal to qp? What about the constant pressure makes the two equal?

### Re: Delta H v. q

Posted: Thu Jan 30, 2020 11:35 am
Delta H is equal to q only when the gas is at a constant pressure. By definition, enthalpy (deltaH) is the amount of heat released/absorbed at a CONSTANT PRESSURE, so the heat required to change temp of gas at a constant pressure is the same as enthalpy.

### Re: Delta H v. q

Posted: Thu Jan 30, 2020 11:36 am
Angela Prince 1J wrote:Delta H is equal to q only when the gas is at a constant pressure. By definition, enthalpy (deltaH) is the amount of heat released/absorbed at a CONSTANT PRESSURE, so the heat required to change temp of gas at a constant pressure is the same as enthalpy.

So does that mean that the same does not hold for qv?

### Re: Delta H v. q

Posted: Thu Jan 30, 2020 4:11 pm
q refers to the energy, as heat, transferred due to a change in temperature. $\Delta H$ is the heat transferred at constant pressure