BIO 135 Lab Report: Cations and anion reactions

BIO 135 Lab Report: Cations and anion reactions Cations and anion reactions II. Introduction • Reaction between cations and anions will be examined in this lab. The resulting precipitate is indicative of the reaction that occured. • In our lab a lead nitrate solution, Pb(NO3)2 will be mixed with a solution of potassium chromate, K2CrO4 , a yellow precipitate will forms. This precipitate must be a combination of K+ or Pb2+ cation and CrO4 2- or NO3 2- anion. Since most potassium salts and nitrates are soluble in water, PbCrO4 must be the precipitate. The equation for this reaction is: • Pb2+ + CrO4 2- - PbCrO4 Purpose—a concise statement about the lab’s objective Background— For this week's lab, I will conduct the following Model ChemLab experiment: Cations and Anion Reaction. This experiment will demonstrate a double replacement reaction of ionic compounds. This experiment demonstrates ionic compounds. In this experiment, I will mix two ionic compounds. Both compounds are soluble in water. If a reaction occurs between these two compounds, then a precipitate will form because one of the two resultant compounds is not soluble in water. This is evidence that a reaction occurred. Findings— The following reaction will occur: Lead nitrate + Potassium chromate = Potassium nitrate + Lead chromate. The following is the balanced chemical reaction: Pb(NO3)2 + K2CrO4 à 2 KNO3 + PbCrO4. III. Procedure Step 1 Add 50 ml(s) of potassium chromate 1M solution in a 100 ml beaker. Use the Chemicals selection from the Toolbar. Select All Chemicals from the dropdown menu. Using the dropdown menu, select 1 M potassium chromate. Change the volume to 50 mL. Make sure that on the lower part of the window that you have indicated that the potassium chromate is to be added to a new 100 mL beaker. Click OK. A beaker will appear on the workspace. Half of the beaker will appear white—this is the 50 mL of potassium chromate.