An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?
Answer (2)
The filtrate is blue, so the soluble solid is blue, which is solid X.
The residue is white, so the insoluble solid is white, which is solid Y.
Therefore, the mixture contains solids X and Y.
The answer is X an d Y
Explanation
Analyze the problem We are given a table with the color and solubility of four solids: W, X, Y, and Z. We know that a mixture of two of these solids is added to water, stirred, and filtered. The filtrate is blue, and the residue is white. We need to determine which two solids are in the mixture.
Identify the soluble solid The filtrate contains the soluble solid(s), and the residue contains the insoluble solid(s). Since the filtrate is blue, the soluble solid must be blue. Looking at the table, the only blue and soluble solid is X. Therefore, solid X is present in the mixture.
Identify the insoluble solid Since the residue is white, the insoluble solid must be white. Looking at the table, the only white and insoluble solid is Y. Therefore, solid Y is present in the mixture.
Conclusion Therefore, the mixture contains solid X and solid Y.
Examples
This type of problem is useful in chemistry for identifying unknown substances based on their physical properties like color and solubility. For example, if you have a mixed sample of chemicals and you observe that after dissolving it in water, the solution is blue and some white solid remains undissolved, you can deduce the presence of a blue soluble compound and a white insoluble compound.
A current of 15.0 A flowing for 30 seconds results in a charge of 450.0 Coulombs. This charge corresponds to approximately 2.81 × 10²¹ electrons. Therefore, about 2.81 trillion electrons flow through the device in that time frame.
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