## Energy of a system

Bryce Ramirez 1J
Posts: 120
Joined: Sat Aug 24, 2019 12:16 am

### Energy of a system

When determine whether the energy of a system is increasing or decreasing in energy, can someone explain the difference between when energy (heat) gets added/ removed and what sign that would be.

Long Luong 2H
Posts: 51
Joined: Thu Sep 19, 2019 12:16 am

### Re: Energy of a system

When delta H is positive, the system absorbed heat. When delta H is negative, heat is removed. Delta H is the change in enthalpy of a system

Yiyang Jen Wang 4G
Posts: 76
Joined: Wed Nov 21, 2018 12:18 am

### Re: Energy of a system

If Delta H is negative, the reaction is exothermic, heat released; if Delta H is positive, the reaction is endothermic, heat absorbed.

Dina Marchenko 2J
Posts: 54
Joined: Thu Jul 25, 2019 12:16 am

### Re: Energy of a system

In an exothermic reaction, the system loses energy in the form of heat, so the value of delta H and U is negative. When the system undergoes an endothermic reaction, it gains energy in the form of heat, so delta H and U is positive.

CosetteBackus_4F
Posts: 23
Joined: Wed Feb 20, 2019 12:18 am

### Re: Energy of a system

Delta H is the enthalpy of a reaction. It is calculated by the difference in the energy of the products and the reactants. If the reaction gives a net release of heat, it is exothermic and delta H is negative (heat is released into the surroundings). If the reaction requires heat, it is endothermic, and delta H is positive.

AveryAgosto
Posts: 76
Joined: Wed Sep 18, 2019 12:16 am

### Re: Energy of a system

When delta H is negative, the rxn is exothermic and releases heat. When delta H is positive the rxn is endothermic and absorbs heat.

Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

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