Carbonic acid (H2CO3) is a weak diprotic acid with K a1=4.4310?7 and K a2=4.7310
ID: 776060 • Letter: C
Question
Carbonic acid (H2CO3) is a weak diprotic acid with Ka1=4.4310?7 and Ka2=4.7310?11.
A) What volume of 0.200M HCl is required for the complete neutralization of 1.60g of NaHCO3(sodium bicarbonate)?
B)What volume of 0.170M HCl is required for the complete neutralization of 1.00g of Na2CO3(sodium carbonate)?
C) A sample of NaOH (sodium hydroxide) contains a small amount of Na2CO3 (sodium carbonate). For titration to the phenolphthalein endpoint, 0.180g of this sample requires 23.98 mL of 0.100 M HCl. An additional 0.700 mL of 0.100 M HCl is required to reach the methyl orange endpoint. What is the percentage of Na2CO3 by mass in the sample?
Explanation / Answer
a) What volume of 0.200M HCl is required for the complete neutralization of 1.60g of NaHCO3(sodium bicarbonate)?
Use M1V1 (acid) = M2V2 (base)
0.2M x V1 = no. o moles of NaHCO3
0.2M x V1 = 1.6g/84g/mol = 0.019mol
V1 =0.09523 L = 95.24mL