Topic: Reactions in Aqueous Solution Do Now: Label the following at (aq) or (s) 1. NaBr 2. PbNO3 3. KOH 4. CuSO4 5. Ba2S Formation of a precipitate 2 aqueous solutions mixing to produce a new compound that is insoluble (a solid) Demo • KI + PbNO3 KNO3 + PbI • AgNO3 + NaCl AgCl + NaNO3 Reactions in aqueous solution • Many reactions, esp. many double replacement reactions, occur in water. • What happens when substances dissolve in water? • Depends on if they are ionic or covalent. Dissolving an Ionic Substance in water it splits into the ions that make up the compound • • • • • Example: NaCl(s) Na+(aq) + Cl-(aq) CaCl2(s) Ca2+(aq) + 2Cl-(aq) AlCl3(s) Al3+(aq) + 3Cl-(aq) The ions are spread out among the water molecules. Lets check to see if there are really ions • Conductivity = conduct electricity – Need charged particles (ions) to travel Electrolytes • = compounds that conduct electricity • Ionic compounds that dissolve in water are electrolytes Dissolving a Covalent Substance in water split into individual molecules NOT IONS • Ex: sucrose • C12H22O11(s) C12H22O11(aq) • The sugar molecules are spread out among the water molecules.