In a endothermic reaction energy from an outside source is continuously being added.
Mixture. Distilled Water may be a pure substance, however, there are many minerals and such that are in tap water, making it a mixture.
<span>The value of enthalpy of a reaction can be a useful tool in determining the type of reaction it is. If the enthalpy is negative the reaction is exothermic and if the enthalpy is positive the reaction is endothermic. Hope this answers the question. Have a nice day.</span>