This lab was conducted to find the key differences between the quantity of heat (q) and ∆H of a substance. Different masses of substances CaCl2 and NH4NO3 were dissolved in water to see how changing mass impacts the q and ∆H of a substance. When the two substances dissolve, they become ions. CaCl2 dissolves in a reaction of: CaCl2 Ca2+aq + 2Cl1-aq while NH4NO3 dissolve in a reaction of: NH4NO3 NH41+aq + NO31-aq . As shown in these reactions, when ionic compounds dissolve in water, they break into their individual charged ions. The compounds are held together through ionic bonds, but when they dissolve, ionic bonds are broken and ion dipole attractions form instead. This change in bonding indicates that there is a change in energy, which can create endothermic or exothermic reactions. Endothermic reactions are those when energy is drawn into the system in order to perform the reaction, while exothermic reactions are those when energy is released into the surroundings. Exothermic reactions are caused when the ionic bonds have more energy than those of the ion dipole attractions, so they give off energy after the substance is dissolved. In this lab, this is shown through the reaction of CaCl2 Ca2+aq + 2Cl1-aq.
