When a paper towel absorbs water, is it a physical or chemical change?
1 answer:
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Answer:
- See the image attached. It is taken from an online chemistry textbook.
- See the explanation below.
Explanation:
<em>Sodium chloride</em> consits of sodium cations (positive ions), Na⁺, and chloride anions (negative ions), CL⁻.
<u>Pure sodium chloride</u> is packed in crystals: sodium ions and chloride ions are packed together and the ions are in fixed positions. There are not free electrons that can move. Thus, sodium chloride doesn't conduct electricity, because there are no electrons or ions which are free to move.
In aqueous solution, sodium chloride units dissociates into their ions:
Those ions are freely to move in the solution, and such they are charge carriers, which conduct the electricity.
As explained above, in solid sodium chloride, the ions cannot move and there is not flow of current.
That is why solid pure salt of NaCl does not conduct electricity and the solutions of NaCl do conduct electricity.
The image attached show both diagrams. In the diagram A, the ions are packed together, showing that they cannot move. In the diagram B, the ions are dissolved in water, showing that they can move and carry the charge, allowing the flow of current.
