1093-g sample of impure Na2CO3 was analyzed by residual precipitimetry. After adding 50.00 mL of 0.06911 M AgNO3, the sample was back-titrated with 0.05781 M KSCN, requiring 27.36 mL to reach the endpoint. The percentage Na2CO3 (MW = 106.0 g/mole) in the tested sample is ________ % ?
1. 1093-g sample of impure Na2CO3 was analyzed by residual precipitimetry. After adding 50.00 mL of 0.06911 M AgNO3, the sample was back-titrated with 0.05781 M KSCN, requiring 27.36 mL to reach the endpoint. The percentage Na2CO3 (MW = 106.0 g/mole) in the tested sample is ________ % ?
Note: Express final answer using least number of significant figures.
2. The alkalinity of natural waters is usually controlled by OH- (MW = 17.01 g/mole), CO3-2 (MW = 60.01 g/mole), and HCO3- (MW = 61.01 g/mole), which may be present singularly or in combination. Titrating a 10.0-mL sample to a phenolphthalein endpoint requires 38.12 mL of a 0.5812 M solution of HCl, and an additional 18.67 mL of the same titrant to reach the methyl orange endpoint.
The composition of the sample is _________% CO3-2 and ___________ % OH-
Note: Express final answers using least number of significant figures.
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