snowysummer Posted October 19, 2005 Share Posted October 19, 2005 Can anybody tell me what primary standard is usually used to standardize NaCl? Link to comment Share on other sites More sharing options...
akcapr Posted October 19, 2005 Share Posted October 19, 2005 Whats a primary standard? Link to comment Share on other sites More sharing options...
snowysummer Posted October 20, 2005 Author Share Posted October 20, 2005 primary standard is a substance that has high purity. Dissolve the standard into solution, then titrate it against a sample to determine the sample's concentration. Link to comment Share on other sites More sharing options...
akcapr Posted October 20, 2005 Share Posted October 20, 2005 Its hard to understand your question, try explaining it better. Are titrateing an acid or something? Link to comment Share on other sites More sharing options...
woelen Posted October 20, 2005 Share Posted October 20, 2005 Can anybody tell me what primary standard is usually used to standardize NaCl? This article may help you. http://www.chem.uidaho.edu/faculty/ifcheng/Chem%20253/labs/Experiment%206.doc Whether silver ntirate is a primary standard or not is debated somewhat. I think it can be a primary standard, provided a really high grade sample is used. In the paper, I have given here, the silver nitrate must be standardized. You could do the other way around, standardizing your NaCl. Link to comment Share on other sites More sharing options...
scientistsahai Posted October 20, 2005 Share Posted October 20, 2005 A primary standard A substance of a known high degree of purity that undergoes one invariable reaction with the other reactant of interest. A primary standard is a reagent that is extremely pure, stable, has no waters of hydration, and has a high molecular weight. Some primary standards for titration of acids: sodium carbonate: Na2CO3, mol wt. = 105.99 g/mol tris-(hydroxymethyl)aminomethane (TRIS or THAM): (CH2OH)3CNH2, mol wt. = 121.14 g/mol This is what you were looking for : Some primary standards for titration of bases: potassium hydrogen phthalate (KHP): KHC8H4O4, mol wt. = 204.23 g/mol potassium hydrogen iodate: KH(IO3)2, mol wt. = 389.92 g/mol Some primary standards for redox titrations: potassium dichromate: K2Cr2O7, mol wt. = 294.19 g/mol Link to comment Share on other sites More sharing options...
insane_alien Posted October 20, 2005 Share Posted October 20, 2005 i made some primary standards on wednesday. too easy. silver nitrate is the primary standard for NaCl and NaCl is the primary standard for AgNO3. Link to comment Share on other sites More sharing options...
ecoli Posted October 20, 2005 Share Posted October 20, 2005 Funny, I just did that for my chem lab, about five minutes ago... accept we were using a primary standard of KHP to find the concentration of NaOH. Same concept, though. Link to comment Share on other sites More sharing options...
akcapr Posted October 21, 2005 Share Posted October 21, 2005 WHy cant you jsut use say KOH or NaOH as a titration base? I know you can but why isnt it "standard"? Link to comment Share on other sites More sharing options...
jdurg Posted October 21, 2005 Share Posted October 21, 2005 Because NaOH and KOH both absorb water from the air in their 'pure' form, and solutions of the bases absorb CO2 from the air to form the bicarbonates. Since the composition of your starting compound changes as soon as you open the bottle, it cannot be used as a standard. Link to comment Share on other sites More sharing options...
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