Q: (a) \$H_2O_2 + O_3 \rightarrow H_2O + 2O_2\$(b) \$H_2O_2 + Ag_2O \rightarrow 2Ag + H_2O + O_2\$Role of hydrogen peroxide in the above reactions is respectively:

(a) \$H_2O_2 + O_3 \rightarrow H_2O + 2O_2\$In this reaction, \$O_3\$ is reduced into \$O^{-2}\$ ion .(b) \$H_2O_2 + Ag_2O \rightarrow 2Ag + H_2O + O_2\$In this reaction, \$Ag_2O\$ is reduced to Ag .Hence, \$H_2O_2\$ acts as reducing agent in both the reactions.

Q: The reaction of aqueous \$KMnO_4\$ with \$H_2O_2\$ in acidic conditions gives:

The reaction of aqueous \$KMnO_4\$ with \$H_2O_2\$ in acidic conditions gives:\$3H_2SO_4+ 2KMnO_4 + 5H_2 O_2 \rightarrow 5O_2 + 2MnSO_4 + 8H_2O + K_2SO_4\$The oxidation number of \$Mn\$ in \$MnSO_4\$ is \$+2\$.Hence, option \$B\$ is correct.

Q: \${ H }_{ 2 }{ O }_{ 2 }\$ solution used for hair bleaching is sold as a solution of approximately 5.0 g \${ H }_{ 2 }{ O }_{ 2 }\$ per 100mL of the solution. The molecular mass of \${ H }_{ 2 }{ O }_{ 2 }\$ is 34. The molarity of this solution is approximately :

Man of \$H_2O_2=5\ g\$molar man of \$H_2O_2=34\$number of mole \$=\dfrac{5}{34}=0.147\$moraity \$\dfrac{0.147}{100\ m.p\times 10^{-3}}=1.47M\simeq1.5M\$

Q: In which of the following reactions, \$H_{2}O_{2}\$ acts as a reducing reagent ?

\$HOCl + H_{2}O_{2}\overset{H^+}{\rightarrow}H_{3}O^{+} + Cl^{-} + O_2\$Here, the \$H_2O_2\$ act as the reducing agent, as the \$Cl\$ has \$+1\$ oxidation state of in \$HOCl\$ and after reaction with the \$H_2O_2\$ , in the presence of the acid, it reduces the \$Cl\$ in \$HOCl\$ to \$Cl^{-}\$ having -1 oxidation state. So, as \$Cl\$ oxidation state decreases from the +1 to -1 oxidation state, hence the \$H_2O_2\$ is acting as the reducing agent.

Q: The reaction \$H_2S+H_2O_2\rightarrow S+2H_2O\$ describes:

The reaction \$H_2S+H_2O_2\rightarrow S+2H_2O\$ manifests oxidizing nature of \$H_2O_2\$ as it oxidises S from -2 to 0 oxidation states.Hence option C is correct.

Q: Which of the following equations depict the oxidizing nature of \$H_2O_2\$?

Oxidizing nature of \$H_2O_2\$ means it oxidizes other substance and itself gets reduced. In such reactions \$O_2\$ is not evolved. In (A), \$MnO_4^-\$ gets reduced from \$Mn^{7+}\$ to \$Mn^{2+}.\$In (B), \$Fe^{3+}\$ gets reduced to \$Fe^{2+} \$.In (C), \$ I^-\$ gets oxidised to \$I_2 \$In (D), \$KIO_4\$ gets reduced from \$I^{7+}\$ to \$I^{5+} \$ Option C is correct.

Q: Hydrogen peroxide in its reaction with \$KIO_4\$ and \$NH_2OH\$ respectively is acting as:

\$KIO_4 + H_2O_2 \rightarrow KIO_3 + H_2O + O_2\$\$NH_2 OH+ 3H_2 O_2 \rightarrow HNO_3 + 4H_2O\$.From this above reaction, we can easily figure out that hydrogen peroxide is acting as reducing and oxidising agent respectively.

Question 1

(a) $H_2O_2 + O_3 \rightarrow H_2O + 2O_2$(b) $H_2O_2 + Ag_2O \rightarrow 2Ag + H_2O + O_2$Role of hydrogen peroxide in the above reactions is respectively:

Accepted Answer

(a) $H_2O_2 + O_3 \rightarrow H_2O + 2O_2$In this reaction, $O_3$ is reduced into $O^{-2}$ ion .(b) $H_2O_2 + Ag_2O \rightarrow 2Ag + H_2O + O_2$In this reaction, $Ag_2O$ is reduced to Ag .Hence, $H_2O_2$  acts as reducing agent in both the reactions.

Question 2

The reaction of aqueous $KMnO_4$ with $H_2O_2$ in acidic conditions gives:

Accepted Answer

The reaction of aqueous $KMnO_4$ with $H_2O_2$ in acidic conditions gives:$3H_2SO_4+ 2KMnO_4 + 5H_2 O_2 \rightarrow 5O_2 + 2MnSO_4 + 8H_2O + K_2SO_4$The oxidation number of $Mn$ in $MnSO_4$ is $+2$.Hence, option $B$ is correct.

Question 3

${ H }_{ 2 }{ O }_{ 2 }$ solution used for hair bleaching is sold as a solution of approximately 5.0 g ${ H }_{ 2 }{ O }_{ 2 }$ per 100mL of the solution. The molecular mass of ${ H }_{ 2 }{ O }_{ 2 }$ is 34. The molarity of this solution is approximately :

Accepted Answer

Man of $H_2O_2=5\ g$molar man of $H_2O_2=34$number of mole $=\dfrac{5}{34}=0.147$moraity $\dfrac{0.147}{100\ m.p\times 10^{-3}}=1.47M\simeq1.5M$

Question 4

In which of the following reactions, $H_{2}O_{2}$ acts as a reducing reagent ?

Accepted Answer

$HOCl + H_{2}O_{2}\overset{H^+}{\rightarrow}H_{3}O^{+} + Cl^{-} + O_2$Here, the $H_2O_2$ act as the reducing agent, as the $Cl$ has $+1$ oxidation state of in $HOCl$ and after reaction with the $H_2O_2$ , in the presence of the acid, it reduces the $Cl$ in $HOCl$ to $Cl^{-}$ having -1 oxidation state. So, as $Cl$ oxidation state decreases from the +1 to -1 oxidation state, hence the $H_2O_2$ is acting as the reducing agent.

Question 5

The reaction $H_2S+H_2O_2\rightarrow S+2H_2O$ describes:

Accepted Answer

The reaction $H_2S+H_2O_2\rightarrow S+2H_2O$ manifests oxidizing nature of $H_2O_2$ as it oxidises S from -2 to 0 oxidation states.Hence option C is correct.

Question 6

From the following statements regarding $H_2O_2$, choose the incorrect statement?

Accepted Answer

(A) Hydrogen peroxide can act as oxidizing as well as reducing agent.For example, in acidic medium, it oxidizes ferrous ions to ferric ions.$2Fe^{2+} +H_2O_2 +2H^+\rightarrow 2Fe^{3+} +2H_2O$In acidic medium, hydrogen peroxide reduces HOCl to chloride ion.$HOCl + H_2O_2 \rightarrow H^++Cl^-+H_2O + O_2$Thus, the option A is incorrect.(B) It decomposes on exposure to light to form water and oxygen.$2H_2O_2 \rightleftharpoons 2H_2O + O_2$Thus, the option (B) is correct.(C) It has to be stored in plastic or wax, lined glass bottles in dark to prevent its decomposition.Thus, the option (C) is correct.(D) It has to be kept away from dust as it decomposes in presence of dust.Thus, the option (D) is correct.

Question 7

Which of the following equations depict the oxidizing nature of $H_2O_2$?

Accepted Answer

Oxidizing nature of $H_2O_2$ means it oxidizes other substance and itself gets reduced. In such reactions $O_2$ is not evolved. In (A), $MnO_4^-$ gets reduced from $Mn^{7+}$ to $Mn^{2+}.$In (B), $Fe^{3+}$ gets reduced to $Fe^{2+} $.In (C), $ I^-$ gets oxidised to $I_2 $In (D), $KIO_4$ gets reduced from $I^{7+}$ to $I^{5+} $ Option C is correct.

Question 8

In which of the following reaction ${ H }_{ 2 }{ O }_{ 2 }$ acts as the reducing agent ?

Accepted Answer

A reducing agent gets oxidised while reducing the other reactant. Hence it should release electrons.So in reactions,$H_2O_2-2e^- \longrightarrow O_2+2H^+$ & $H_2O_2+2OH^--2e^- \longrightarrow O_2+2H_2O$ ;  $H_2O_2$ acts as reducing agent.

Question 9

Hydrogen peroxide is prepared in the laboratory by:

Accepted Answer

Hydrogen peroxide can be prepared in the laboratory by the action of ice cold, dilute sulphuric acid on sodium peroxide or hydrated barium peroxide $(BaO_2. 8H_2O)$. A calculated quantity of sodium peroxide is added in small quantities to $20\%$ ice cold solution of sulphuric acid. The reaction is as follows:$Na_2O_2(s)  + H_2SO_4\rightarrow Na_2SO_4(s)  + H_2O_2(l)$Most of the sodium sulphate separates out on cooling as crystals of $Na_2SO_4.10H_2O$. Thus, $30\%$ of hydrogen peroxide containing small amount of sodium sulphate is obtained. Barium peroxide is made into a thin paste and added slowly to ice-cold dilute sulphuric acid. The reaction is as follows:$BaO_2(s)  + H_2SO_4(aq)\rightarrow BaSO_4(s) + H_2O_2(l)$Barium sulphate is allowed to settle down as a precipitate and filtered off. The filtrate obtained is a dilute solution of hydrogen peroxide. Phosphoric acid can be used in place of sulphuric acid. Alternatively, carbon dioxide gas may be passed through hydrated barium peroxide paste in ice cold water, in a slow stream.                      $2BaO_2(s)  +  2H_3PO_4(aq)\rightarrow Ba(PO_4)_2(s) + 3H_2O_2(l)$                  $BaO_2(s) + CO_2 + H_2O_2\rightarrow BaCO_3(s) + H_2O_2(l)$The precipitated barium peroxide or barium carbonate is filtered off which leaves hydrogen peroxide.

Question 10

Hydrogen peroxide in its reaction with $KIO_4$ and $NH_2OH$ respectively is acting as:

Accepted Answer

$KIO_4 + H_2O_2  \rightarrow KIO_3 + H_2O + O_2$$NH_2 OH+ 3H_2 O_2  \rightarrow HNO_3 + 4H_2O$.From this above reaction, we can easily figure out that hydrogen peroxide is acting as reducing and oxidising agent respectively.

Uses of Hydrogen Peroxide

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Hydrogen Peroxide - preparation, Properties, Structure and Uses

Properties and structure of hydrogen peroxide

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Properties and Structure of Hydrogen Peroxide