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### Delta H

Posted: Sun Jan 27, 2019 2:21 pm
What do positive and negative delta H mean?

### Re: Delta H

Posted: Sun Jan 27, 2019 2:24 pm
A positive delta H indicates that the reaction is endothermic and requires heat to be absorbed while a negative delta H indicates that the reaction is exothermic and releases energy.

### Re: Delta H

Posted: Sun Jan 27, 2019 2:25 pm
Positive delta H means an Endothermic reaction because is greater than 0. Negative delta H is an exothermic reaction because heat is released.

### Re: Delta H

Posted: Sun Jan 27, 2019 2:27 pm
Endothermic is positive ∆H because the enthalpy of the products is greater than the enthalpy of the reactants, so energy is absorbed. The opposite is true for exothermic, since energy is released.

### Re: Delta H

Posted: Sun Jan 27, 2019 3:53 pm
$\Delta H =$ $H_{products} - H_{reactants}$ , H being enthalpy. If the enthalpy, or total energy, of the products is greater than the energy of the reactants, then ΔH is positive and it is an endothermic reaction. If the energy of the products is less than the energy of the reactants, ΔH is negative and the reaction is exothermic.

### Re: Delta H

Posted: Sun Jan 27, 2019 4:06 pm
Delta refers to the change between the final and the initial of value. When you have a negative delta H this is due to the fact that you have lost enthalpy, so it makes sense that the reaction would be exothermic (give off heat). The reverse is true for a reaction with positive delta H. It is an endothermic reaction.

### Re: Delta H

Posted: Sun Jan 27, 2019 4:47 pm
This is how Dr. Lavelle explained it. Positive delta H signifies that it is endothermic which means energy is being put into the system. Negative delta H is exothermic which means energy is leaving the system. In this way, you can rationalize the positive and negative better as gain and loss of energy from the system.

### Re: Delta H

Posted: Sun Jan 27, 2019 4:53 pm
H stands for enthalpy. So delta H represents the change in enthalpy during a reaction. If delta H is positive then the reaction requires energy and is endothermic. If delta H is negative then the reaction releases energy and is exothermic.

### Re: Delta H

Posted: Sun Jan 27, 2019 5:54 pm
positive delta H is endothermic and negative delta H is exothermic

### Re: Delta H

Posted: Sun Jan 27, 2019 6:05 pm
+H = endothermic the reactions needs heat
-H = exothermic the reaction gives off heat

### Re: Delta H

Posted: Sun Jan 27, 2019 6:20 pm
A positive delta H indicates that the reaction is endothermic and that the reaction takes in heat/energy to occur and if it is negative that means that the reaction is exothermic and releases heat and energy.

### Re: Delta H

Posted: Mon Feb 11, 2019 11:19 pm
A Positive ΔH is an endergonic reaction. A negative ΔH is an exergonic reaction.