i got my test back and i dont know why i got this wrong??
can you please help me?
thanks
A researcher has an unknown biological compound that she knows is a triprotic acid. She weighs out 2.143 grams of the unknown acid, dissolves it in water, adds an indicator, and titrates it to neutrality using 81.99 mL of 0.1195 M NaOH. What is the molecular weight of the acid?
answer:_______ AMU
2007-08-08 10:24:36 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
H3A + 3 NaOH --> Na3A + 3 H2O
Ratio of acid to base is 1:3
0.08199 L X 0.1195 M = 0.009798 moles NaOH
0.09798 moles NaOH X (1 mol H3A/3 mol NaOH) = 0.003266 moles H3A.
Molar mass H3A = 2.143 g/0.003266 mol = 656.2 g/mol
2007-08-08 10:37:03 · answer #1 · answered by William Q 5 · 1⤊ 0⤋
If you email me this problem, I'll work it out on paper, scan it, attach it to an email, and email it back.
It doesn't look to hard to me. The answer's probably 97g/mol because it's probably phosphoric acid.
2007-08-08 10:32:52 · answer #2 · answered by Anonymous · 0⤊ 1⤋
2.143gA/81.99mLNaOH x 1000mLNaOH/0.1195molNaOH x 3molNaOH/1molA = 656gA/mol
2007-08-08 11:03:33 · answer #3 · answered by steve_geo1 7 · 0⤊ 0⤋