Stoichiometric Characterization Lab Report

☐ Figure 1. Mass percentages of sodium, chlorine, nitrogen, and oxygen in the studied mixture. Discussion In the first part of the experiment, many separate reactions take place. First, sodium percarbonate is dissolved in water to break it into its specific ions: Na 2 CO 3 · n H 2 O 2 ( s ) → 2 N a + ( aq ) + CO 3 2 – ( aq ) + n H 2 O 2 ( aq ); next, iodide is added to the solution which reacts with aqueous hydrogen peroxide: H 2 O 2 ( aq ) + 2 H + ( aq ) + 3 I – ( aq ) → 2 H 2 O( l ) + I 3 – ( aq ); finally, sodium thiosulfate solution is added to the mixture to determine how much triiodide was produced in the previous reaction: I 3 – ( aq ) + 2 S 2 O 3 2 – ( aq ) → 3 I – ( aq ) + S 4 O 6 2 – ( aq ). In the second part of the experiment, one main reaction occurs. In an aqueous solution of sodium chloride (NaCl) and sodium nitrate (NaNO 3 ), silver reacts with the chlorine ions to form silver chloride precipitate: Ag + ( aq ) + Cl – ( aq ) → AgCl ( s ). In addition to this main reaction, once all of the chlorine anions are consumed, excess silver reacts with chromate ions in a potassium chromate indicator (K 2 CrO 4 ) to make a red tint in the solution: 2 Ag + ( aq ) + CrO 4 2 – ( aq ) → A g 2 CrO 4 ( s ), this tint is indicative of the chloride fully reacted. In experiment one, the end goal is to find the ratio of sodium carbonate to hydrogen peroxide. First, we find the mols of thiosulfate added to the solution; because the solution was (0.1 mol/L) we can simply multiply the number of mL added to the solution by this ratio and divide by 1000 due to the conversion between mL and L. In the case of my data, I added 0.000277 mols S 2 O 3 2 – . After we ’ ve obtained this value, we can