Hosphoric acid is a triprotic acid ( K a1 = 6.9 × 10 − 3 Ka1=6.9×10−3 , K a2 = 6.2 × 10 − 8 Ka2=6.2×10−8 , and K a3 = 4.8 × 10 − 13 Ka3=4.8×10−13 ). To find the pH of a buffer composed of H 2 PO − 4 ( aq ) H2PO4−(aq) and HPO 2 − 4 ( aq ) HPO42−(aq) , which p K a Ka value should be used in the Henderson–Hasselbalch equation? p K a1 Ka1 = 2.16 p K a2 Ka2 = 7.21 p K a3 Ka3 = 12.32 Calculate the pH of a buffer solution obtained by dissolving 15.0 15.0 g of KH 2 PO 4 ( s ) KH2PO4(s) and 31.0 31.0 g of Na 2 HPO 4 ( s ) Na2HPO4(s) in water and then diluting to 1.00 L. p H = pH=

These questions are based on the attached photo. the experiment is about burning magnesium metal with oxygen. 1. write the balanced chemical equation for the reaction you are performing. 2. calculate the mass of magnesium metal used in each trial. o trial 1: o trial 2: 3. calculate the actual yield of magnesium oxide for each trial. o trial 1: o trial 2: 4. magnesium is the limiting reactant in this experiment. calculate the theoretical yield of mgo for each trial. o trial 1: o trial 2: 5. determine the percent yield of mgo for your experiment for each trial. o trial 1: o trial 2: 6. determine the average percent yield of mgo for the two trials. your company currently uses a process with a similar cost of materials that has an average percent yield of 91 percent. if the average percent yield of this process is higher than that, this could save the company money. what is your recommendation to the company? support your recommendation using your data, calculations, and understanding of stoichiometry gathered from this lab.