Chemistry – Feb 28, 2018 P3 Challenge – (or nomenclature quiz M or N if not done yet) Translate this sentence into a balanced equation including state descriptors: If chlorine gas is bubbled through an aqueous solution of hydrosulfuric acid, solid elemental sulfur is formed within an aqueous solution of hydrochloric acid.

Chemistry – Feb 28, 2018 Agenda Acids and bases Objective – Driving forces continued Assignment: Finish Driving forces Worksheet 1 Driving Forces Worksheet 2 Agenda Acids and bases Neutralization reactions Gas forming reactions Electron Transfer (time permitting)

2) Formation of water: Acids and Bases Acids are molecular compounds that dissociate to form hydrogen ions, H+. 6 acids dissociate completely and are called strong acids. (memory item) HCl HBr HI HNO3 H2SO4 HClO4 All acids are aqueous solutions. (aq) Strong acids get completely dissociated. All other acids are weak acids that split into ions only a little bit. Bases dissociate in water to form hydroxide ion, OH- Hydroxides of alkali and alkaline earth metals are strong bases that completely dissociate.

2) Formation of water: Acids and Bases Acids react with bases to form water and an ionic salt. Formation of water is a driving force. Ex: HC2H3O2 (aq) + NaOH(aq)  H2O (l) + NaC2H3O2 (aq) Net ionic equations can be found for acid base reactions too. All acids are aqueous solutions. (aq) Strong acids get split. Weak acids are the ONLY (aq) substance that you DO NOT SPLIT when determining a net ionic equation.

3) Formation of a gas If a gas is produced, it will the driving force. Acid base reactions, decomposition reactions, and combustions often form gases. Common gases are CO2, NO2, SO2, NH3, H2S, H2, N2, O2, F2, Cl2 (memorize these) If a product is a gas, then gas formation is a driving force. Ex: K2CO3 (s)  K2O (s) + CO2(g)

4) Transfer of electrons: Oxidation-Reduction How to identify a redox reaction Is there an atom that is an element on one side and in a compound on the other side? (Single Replacement reaction) Is there an element that has a different charge ion on both sides? (Many synthesis and decomposition reactions. Also combustion.) Transfer of electrons is a driving force. Elements are driven to complete octets. Note: All combustion reactions are driven by electron transfer.

Activity Series For single replacement reactions, the determining factor is the place of the two metals in the activity series. In general, a metal can displace any of the metals which are lower in the activity series: Ex: Cu + AgNO3  Cu(NO3)2 + Ag Ex: Cu + Fe(NO3)3  Cu (NO3)2 + Fe Ex: Zn + Fe(NO3)3  Zn (NO3)2 + Fe

Reactivity Series for Halogens In general, a halogen can displace any of the halogens which are lower in the activity series for halogens. Notice that the activity series of halogens is just their order within the periodic table. Ex: F2 + 2 NaBr  2 NaF + Br2 Ex: Br2 + 2 NaCl  2 NaBr + Cl2

Exit Slip - Homework Exit Slip: Write the complete ionic equation then determine the net ionic equation for: NiCl2 (aq) + 2 KOH (aq)  Ni(OH)2 (s) + 2 KCl (aq) What’s Due? (Pending assignments to complete.) Finish Driving forces Worksheet 1 Driving Forces Worksheet 2 What’s Next? (How to prepare for the next day) Read p473, p286-288, p548-549, p280-282