Chemical Reactions

Stewart Pine, Max Handler, Ian Wood, Shane Silverstein, Dylan Pyle 10/6/08 B2 Reaction #1 Magnesium Ribbon and Oxygen 1. Synthesis Reaction and Combustion Reaction 2. 2Mg (s) + O2 (g) → 2MgO (s) is the completed equation. 3. The two reactions are both exothermic. Each Magnesium atom loses two electrons in this equation and each Oxygen atom gains two electrons. Since Oxygen naturally bonds with itself in the air, there are automatically two Oxygen atoms for every Magnesium atom. Therefore, there must be two Magnesium atoms to balance out the equation. Each Magnesium atom has an oxidation state of +2, while the Oxygen atom has an oxidation state of -2. After the heat is added, the swapping of electrons occurs and Magnesium Oxide is formed. This makes it a synthesis reaction because there were two elements, Magnesium and Oxygen, which combined to form a single compound, Magnesium Oxide. It is also a combustion reaction because one of the elements involved was Oxygen. This reaction is always reversible. Reaction #2 Potassium Iodide and Lead Nitrate 1. Double Replacement Reaction 2. Pb(NO3)2 (aq) + 2KI (aq) → 2KNO3 (aq) + PbI2 (s) 3. This reaction is exothermic. The Lead (II) nitrate and the potassium iodide cancel out to have a total charge of zero. When mixed, the potassium splits from the iodide and combines with the nitrate. Here, the potassium has an oxidation state of +1 and the nitrate has an oxidation state of -1. There are two molecules of this. The lead (II) that was formerly combined with the nitrate is now with the iodine, forming lead(II)iodide. In this state, there are two molecules of iodine and only one of lead, so since iodine has an oxidation state of -1, the lead must have an oxidation state of +2. This is a reversible reaction, and is a double replacement reaction because lead replaced nitrate with iodide and the potassium replaced iodide with nitrate, hence a double replacement. Reaction #3 Magnesium and Hydrochloric Acid 1. Metallic Single Replacement Reaction 2. Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g) 3. This reaction is exothermic. The pure magnesium powder and hydrochloric acid cancel to have a total charge of zero. Hydrochloric acid is a combination of hydrogen and

chloride. In this metallic single replacement reaction, the hydrogen is replaced with the magnesium to form pure hydrogen and magnesium chloride. The magnesium has an oxidation state of +2 and the chloride has an oxidation state of -1, but there are two chlorine atoms so it balances out. This reaction is not reversible.