1 7-Zip-Right-click on the file or folder you want to compress and select 7-Zip â Add to archive. 2  In the Add to Archive menu, you can set your compression options. 3  Note that increasing compression levels can significantly increase the time it takes to compress. 7-Zip-Right-click on the file or folder you want to compress and select 7-Zip â Add to archive. 2  In the Add to Archive menu, you can set your compression options. 3  Note that increasing compression levels can significantly increase the time it takes to compress.
Endothermic reactions are the opposite. The new bonds require more energy. This comes from heating the substances, or sometimes, comes from the surrounding environment. Absorbing heat energy from the environment makes everything decrease in temperature so the reaction 'feels' cooler.
Most chemical reactions involve the breaking and formation of chemical bonds. It takes energy to break a chemical bond but energy is released when chemical bonds are formed. If more energy is released than consumed, then the chemical reaction evolves heat and is said to be exothermic. On the other hand if the reaction consumes more energy than it releases then the reaction absorbs heat and is said to be endothermic. Most reactions are exothermic. The amount of heat generated by a reaction can be quantified. The quantity that specifies the amount of heat is known as the enthalpy . If is positive then the reaction is endothermic and if it is negative the reaction is exothermic.