When a student transfered HCL to a graduated cylinder for addition to the sample

Question

When a student transfered HCL to a graduated cylinder for addition to the sample , several drops ran down the outside of the cylinder and on to the laboratory bench . Explan the potential danger of this situation , and suggest a good way to clean up the spill.

The percent chloride in an unknown sample may be determined in a manner similar to that used for the determination of the percent sulfate. Suppose that a 0.6123-g uknown choloride - contaning smaple was dissolved , and AgCL precipated by adding AgNO3 solution. The precipitate was filtered , ignitied , and found to weight 0.3324 g. What was the percent chloride in the unknown.

A student , following the insstructions for this experiment , precipated and disgested BaSO4. After allowing the precipitate to settle, she added a few drops of BaCl2 solution , and the previously clear solution became cloudy. Explan what happened?

Explain why AgNO3 solution is used to test the rinse water after the BaSO4 precipate has been transferred to the filter paper.

Explanation / Answer

As the acid will destroy the cloths and fumes are not good for health. This will be quenched with Saturated solution of bases like NaOH (it will neutralise the acid form salts, which are soluble in water).

0.3324gr AgCl contains =( 0.3324 ) (35.5/143.32) gr chlorine

= 0.0823 gr chlorine

0.6123 unknown chloride reacted to form 0.0823 gr of chloride product

%age of chlorine in unknown sample = 0.0823/0.6123= 13.5%

Due to precipitation process cloudy solution formed.

If any more precipitate left, that will be precipitated. Hence AgNO3 used for rinsing purpose.

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