Download App

Redox Reactions — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryRedox Reactions3 Marks
Question
Balance the following redox reactions by ion-electron method:
$\text{Cr}_2\text{O}_7^{2-}+\text{SO}_2(\text{g})\rightarrow\text{Cr}^{3+}(\text{aq})+\text{SO}^{2-}_4(\text{aq})$ (in acidic solution).
✓

Answer

Following the steps as in part (a), we have the oxidation half reaction as:
$\text{SO}_{2(\text{g})}+2\text{H}_2\text{O}_{(\text{l})}\rightarrow\text{SO}^{2-}_{4(\text{aq})}+4\text{H}^+_{(\text{aq})}+2\text{e}^-$
And the reduction half reaction as:
$\text{Cr}_2\text{O}^{2-}_{7(\text{aq})}+14\text{H}^{+}_{(\text{aq})}+6\text{e}^-\rightarrow2\text{Cr}^{3+}_{(\text{aq})}+7\text{H}_2\text{O}_{(\text{l})}$
Multiplying the oxidation half reaction by 3 and then adding it to the reduction half reaction, we have the net balanced redox reaction as:
$\text{Cr}_2\text{O}^{2-}_{7(\text{aq})}+3\text{SO}_{2(\text{g})}+2\text{H}^{+}_{(\text{aq})}\rightarrow2\text{Cr}^{3+}_{(\text{aq})}+3\text{SO}^{2-}_{4(\text{aq})}+\text{H}_2\text{O}_{(\text{l})}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Redox Reactions→Redox Reactions — all question types→Chemistry STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

The amount of energy released when $1 \times 10^{10}$ atoms of chlorine in vapour state are converted to $Cl ^{-}$ions according to the equation,
$Cl(g)+e^{-} \rightarrow Cl^{-}(g) \text { is } 57.86 \times 10^{-10} J$
Calculate the electron gain enthalpy of chlorine atom in terms of $kJ mol ^{-1}$ and eV per atom.
→
Suggest a reason as to why CO is poisonous.
→
What is the hybrid state of:
i. B in $\mathrm{BF}_3$.
ii. Al in $\mathrm{AlCl}_3$,
iii. Be in $\mathrm{BeCl}_2$,
iv. C in $\mathrm{CO}_2$ and $\mathrm{C}_2 \mathrm{H}_4$,
v. S in $\mathrm{SO}_2$ and $\mathrm{SO}_3$ ?
→
Define the bond length.
→
Why is $\mathrm{Li}_2 \mathrm{CO}_3$ decomposed at a lower temperature whereas $\mathrm{Na}_2 \mathrm{CO}_3$ at higher temperature?
→
Complete the following reactions:
  1. $\text{CH}_3-\text{CH}=\text{CH}_2+\text{HBr}\xrightarrow{\text{Peroxide}}?$
  2. $\text{CH}_3-\text{Cl}+\text{Na}\xrightarrow{\text{Dry ether}}?$
  3. $\text{CH}_3-\text{CH}-\text{CH}_2-\text{CH}_3\xrightarrow[\Delta]{\text{alc. KOH}}\\ \ \ \ \ \ \ \ \ \ \ \ \ \ |\\ \ \ \ \ \ \ \ \ \ \ \ \ \text{Cl}$
→
For the reaction, $\text{CH}_4(\text{g})+2\text{H}_2\text{S(g)}\rightleftharpoons\text{CS}_2\text{(g)}+4\text{H}_2(\text{g})$ at 1173K, the magnitude of the equilibrium constant, $K_c$​​​​​​​ is 3.6. For each of the following compositions, decide whether reaction mixture is at equilibrium. If it is not, decide in which direction the reaction should go?
  1. $[\text{CH}_4]=1.07\text{M},[\text{H}_2\text{S}]=1.20\text{M},[\text{CS}_2]$
$=0.90\text{M},[\text{H}_2]=1.78\text{M}$
  1. $[\text{CH}_4]=1.45\text{M},[\text{H}_2\text{S}]=1.29\text{M},[\text{CS}_2]$
$=1.25\text{M},[\text{H}_2]=1.75\text{M}$
→
Note: Consider structures I to VII and answer the questions:
  1. $\text{CH}_3-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{OH}$
  2. $\text{CH}_3-\text{CH}_2-\text{CH}-\text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{OH}$
  3. $\ \ \ \ \ \ \ \ \ \ \ \ \text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ |\\\text{CH}_3-\text{C}-\text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ |\\\ \ \ \ \ \ \ \ \ \ \ \ \text{OH}$
  4. $\text{CH}_3-\text{CH}-\text{CH}_2-\text{OH}\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{CH}_3$
  5. $\text{CH}_3-\text{CH}_2-\text{O}-\text{CH}_2-\text{CH}_3$
  6. $\text{CH}_3-\text{O}-\text{CH}_2-\text{CH}_2-\text{CH}_3$
  7. $\text{CH}_3-\text{O}-\text{CH}-\text{CH}_3\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{CH}_3$
Identify the pairs of compounds which are functional group isomers.
→
A mixture of CO and $CO_2$ is found to have a density of $1.50gL^{-1}$ at 20°C and 740mm pressure. Calculate the composition of the mixture.
→
Identify the type of redox reaction taking place in the following.
  1. $3\stackrel{0\ \ \ \ \ \ \ \ \ \ \ \ }{\text{Mg(s)}}+\stackrel{0\ \ \ \ \ \ \ \ \ \ \ }{\text{N}_2\text{(g)}}\ \xrightarrow{\ \ \ \ \ \ \ \ \ \ }\ \stackrel{+2\ \ \ \ -3\ \ \ \ \ \ \ \ }{\text{Mg}_3\text{N}_2\text{(s)}}$
  2. $\stackrel{+5\ \ \ \ \ \ -2\ \ \ \ \ \ \ }{\text{V}_2\text{O}_5\text{(s)}}5\stackrel{0\ \ \ \ \ \ \ \ \ \ }{\text{Ca(s)}}\xrightarrow{\ \ \ \ \ \ \ }2\stackrel{0\ \ \ \ \ \ \ \ }{\text{V(s)}}+\text{5}\stackrel{+2\ \ -2\ \ \ \ \ \ \ \ \ \ }{\text{CaO(s)}}$
  3. $2\stackrel{+1\ +5\ -2\ \ \ \ \ \ \ \ \ \ \ \ }{\text{KClO}_3(\text{s})}\xrightarrow{\ \ \ \ \ \ \ }2\stackrel{+1\ \ -1\ \ \ \ \ \ \ \ \ \ }{\text{KCl(s)}}+3\stackrel{0\ \ \ \ \ \ \ \ \ \ }{\text{O}_2\text{(g)}}$
  4. $\stackrel{0}{\text{Ca}\text{(s)}}+2\stackrel{+1-2}{\text{H}_2\text{O}\text{l}}\ \xrightarrow{\ \ \ \ \ \ \ \ \ \ \ }\stackrel{+2\ \ -2+1\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ }{\text{Ca(OH)}_2(\text{aq})}+\stackrel{0}{\text{H}}_2\text{(g)}$
  5. $\stackrel{0\ \ \ \ \ \ \ \ \ \ \ }{\text{Br}_2(\text{l})}+\stackrel{-1\ \ \ \ \ \ \ \ \ \ \ \ }{2\text{I}^-(\text{aq})}\xrightarrow{\ \ \ \ \ \ \ \ \ \ }\stackrel{1-}{\text{2Br}^-}(\text{aq})+\stackrel{0\ \ \ \ \ \ \ \ \ \ }{\text{I}_2\text{(s)}}$
→