Redox Reactions

The number of electrons transferred can be calculated based on the oxidation states of aluminum and iron in the reaction. Aluminum is oxidized and iron is reduced, and the total number of electrons transferred is 9.

Iodine is released when potassium iodide reacts with copper sulfate due to the reduction of iodine ions.

By balancing the reaction for the liberation of nitric oxide and nitrogen dioxide, the stoichiometric coefficients for copper and nitric acid are found to be 2 and 3, respectively.

Hydrogen sulfide reduces chromium from +6 oxidation state in to +2 oxidation state.
Final Answer:

In the reaction between potassium dichromate and hydrogen sulfide, the chromium in the dichromate is reduced from an oxidation state of +6 to +3.
Final Answer:

Step 1: Assign oxidation numbers to the elements in
The oxidation number of hydrogen is , and the oxidation number of oxygen is .
Step 2: Use the rule for the sum of oxidation numbers
The sum of the oxidation numbers in a neutral compound must be zero. The oxidation numbers of the two hydrogen atoms contribute , and the oxidation numbers of the four oxygen atoms contribute .
Let the oxidation number of sulfur be . Answer: Therefore, the oxidation number of sulfur in is . So, the correct answer is option (1).

Step 1: Understand Redox Reactions A redox reaction is a type of chemical reaction in which the oxidation states of atoms are changed. Oxidation involves the loss of electrons, and reduction involves the gain of electrons. Step 2: Identify the Redox Reaction - In option (1), , hydrogen ( ) is oxidized, and chlorine ( ) is reduced. This is a redox reaction. - In option (2), , there is no change in oxidation states; this is a double displacement reaction, not a redox reaction. - In option (3), , there is no clear change in oxidation states. - In option (4), , oxygen is reduced, but hydrogen is not oxidized. Answer: The correct answer is option (1): .