A buffer prepared by dissolving oxalic acid dihydrate ( H2C2O4⋅2H2O ) and disodium oxalate ( Na2C2O4 ) in 1.00 L of water has a pH of 4.957 . How many grams of oxalic acid dihydrate ( MW=126.07 g/mol ) and disodium oxalate ( MW=133.99 g/mol ) were required to prepare this buffer if the total oxalate concentration is 0.199 M? Oxalic acid has pa values of 1.250 ( pa1 ) and 4.266 ( pa2 ).

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o