Decide whether each chemical reaction in the table below is an oxidation-reduction ("redox") reaction. If the reaction is a redox reaction, write down the formula of the reducing agent and the formula of the oxidizing agent. 2C1₂(g) + Sn (s) CuSO4 (aq) + Zn (s) → ZnSO4 (aq) + Cu (s) 2N₂(g) + 50₂(g) SnCl (s) - 2N₂05 (8) redox reaction? O yes reducing agent: oxidizing agent: redox reaction? O yes reducing agent: oxidizing agent: O yes Ono redox reaction? reducing agent: oxidizing agent: Ono no X

The first reaction is of a strong oxidizer (HNO3) with a metal (Cu) to produce copper nitrate, nitrogen dioxide, and water. Indicate the oxidation state of each element (atom) in the reactants and products.  Describe which species was oxidized, and which species was reduced in this reaction (where did the electrons come from and where did they go?). (Reaction 1)    Cu(s) + HNO3(aq) → Cu(NO3)2(aq) + H2O(l) + NO2(g)

A 4.50 g sample of limestone (impure CaCO3) was dissolved in 0.1M HCl solution according to the following equation.   CaCO3(s) + 2HCl(aq) → CaCl2 (aq) + CO2 (g) + H2O (l)   Excess of (NH4)2C2O4(aq), was added to the resulting solution to precipitate the calcium ions as calcium oxalate, CaC2O4(s). Ca2+(aq) + C2O42-(aq) → CaC2O4 (s)   The precipitate was filtered, dried and weighed at 2.15 g.   (Show your work)                                                                                                 a)    Determine the percentage by mass of calcium carbonate (CaCO3) in the limestone sample. (MM of CaCO3 is 100.09 g/mol)   b) Why we need to dry the precipitate until we get a constant mass?   c) Is the precipitate of calcium oxalate (CaC2O4) stable and in the final form or not? Explain.

When potassium cyanide (KCN) reacts with hydrochloric acid, a poisonous gas of hydrogen cyanide is given off.  The equation describing this process is: KCN(aq) + HCL(aq) ==> KCl(aq) + HCN(g) If 0.140 g pf KCN is completely reacted with hydrochloric acid, calculate the amount of HCN that is formed.