I am going to do a experiment on determinating the relative formula mass of insouluble metal carbonate. The process of the experiment: 1.weight about 1.3g of MCO3 and put it in a large beaker. 2.add 50.00cm^3 into the beaker. 3.wait untill the effervescence ceased. 4.dilute the solution to 250cm^3 and take 25cm^3 of it to a conical flask. 5.add 2-3 drops of methyl orange. 6.titrated with NaOH. 7.End pt, then take reading. I have a few questions: 1.Why can't phenolohthalein be used in this experiment? 2.Why it is not suitable to use HCl and H2SO4 in back titraction between insoluble metal carbonate. I also understand that back titration can be use when the sample contains impurities that interfere with forward titration. Can you guys give me some example? -- "人們之所以戰爭，是因為人們熱愛它。" 潘興將軍 --

※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 219.77.41.29