Explain the following: Cu + 2 AgNO 3 → Cu ( NO 3 ) 2 + 2 Ag is a redox reaction.

The silver nitrate reacts with copper to form hairlike crystals of silver metal and a blue solution of copper nitrate. When a copper is dipped in a solution of silver nitrate, silver ions will be reduced silver metal and copper will be oxidised to copper (II) ions as follows: Cu + 2 Ag + → Cu 2 + + Ag Here, copper is oxidized and silver is reduced. Hence, it is a redox reaction.

Explain the following: AgNO 3 + NaCl → NaNO 3 + AgCl is not a redox reaction.

When a solution of silver nitrate is added to a solution of sodium chloride, the silver ions combine with the chloride ions to form a precipitate of silver chloride. Redox is a type of chemical reaction in which the oxidation states of atoms are changed. In this reaction the elements of each product retains the same oxidation number they had as reactants. Hence, it is not a redox reaction since there is no change in oxidation states.

In the reaction 2 Na + O 2 → 2 NaO , identify the substance which loses electrons and is oxidized.

Sodium reacts with oxygen to form sodium oxide. Oxidation is the loss of electrons or an increase in the oxidation state of an atom, an ion, or of certain atoms in a molecule. In this reaction, sodium is the substance that loses electrons and gets oxidized. The oxidation reaction can be observed as follows: Na - e - → Na +

In the reaction 2 Na + O 2 → 2 NaO , identify the substance which gains electrons and is reduced.

Sodium reacts with oxygen to form sodium oxide. Reduction is the gain of electrons or a decrease in the oxidation state of an atom, an ion, or of certain atoms in a molecule. In this reaction, oxygen is the substance that gains electrons and gets reduced. The reduction reaction can be observed as follows: O + 2 e - → O 2 -

How are the following two reactions related? (a) NH 4 Cl → NH 3 + HCl (b) NH 3 + HCl → NH 4 Cl

The given chemical equations are: NH 4 Cl → NH 3 + HCl This is a reversible reaction, where the ammonium chloride decomposes into the gases ammonia and hydrogen chloride. NH 3 + HCl → NH 4 Cl Ammonium chloride is prepared commercially by combining ammonia with either hydrogen chloride or hydrochloric acid. As we can see that the above reactions are decomposition and combination reactions and hence, they are opposite type of reaction to each other.

In the reaction 3 Fe ( s ) + 4 H 2 O ( g ) → Fe 3 O 4 ( s ) + 4 H 2 ( g ) , select the substance oxidized.

In the reaction 3 Fe ( s ) + 4 H 2 O ( g ) → Fe 3 O 4 ( s ) + 4 H 2 ( g ) , the substance that gets oxidized is Iron. Oxidation is loss of electrons or increase in the oxidation state. It is also addition of oxygen to the element or compound. Iron gets oxidized to form ferric oxide.

In the reaction 3 Fe ( s ) + 4 H 2 O ( g ) → Fe 3 O 4 ( s ) + 4 H 2 ( g ) , select the substance reduced.

In the reaction 3 Fe ( s ) + 4 H 2 O ( g ) → Fe 3 O 4 ( s ) + 4 H 2 ( g ) , the substance that gets reduced is water. Reduction is gain of electrons or decrease in the oxidation state. It is also removal of oxygen from the element or compound. Water gets reduced to form hydrogen.