Download App

The d-and f-Block Elements — Chemistry STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceChemistryThe d-and f-Block Elements2 Marks
Question
Explain chemical reactivity of transition metals.
✓

Answer

$\rightarrow$ Transition metals vary widely in their chemical reactivity.
$\rightarrow$ Many of them are sufficiently electropositive to dissolve in mineral acids, although a few are 'noble' $-$ that is, they are unaffected by simple acids.
$\rightarrow$ The metals of the first series with the exception of copper are relatively more reactive and are oxidised by $1M\ H+,$ though the actual rate at which these metals react with oxidising agents like hydrogen ion $(H+)$ is sometimes slow
$. \rightarrow$ The $E^\circ$ values for $M^{2+}/M$ indicate a decreasing tendency to form divalent cations across the series
$\rightarrow$ This general trend towards less negative $E^\circ$ values is related to the increase in the sum of the first and second ionization enthalpies.
$\rightarrow$ It is interesting to note that the $E ^{\ominus}$ values for $Mn , Ni$ and $Zn$ are more negative than expected from the general trend.
$\rightarrow$ An examination of the $E ^{\ominus}$ values for the redox couple $M ^{3+} / M ^{2+}$ shows that $Mn ^{3+}$ and $Co ^{3+}$ ions are the strongest oxidising agents in aqueous solutions. The ions $Ti ^{2+}, V ^{2+}$ and $Cr ^{2+}$ are strong reducing agents and will liberate hydrogen from a dilute acid, e.g.,
$\ce{2 Cr ^{2+}( aq )+2 H ^{+}( aq ) \rightarrow 2 Cr ^{3+}( aq )+ H _2(g)}$

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 "2 Marks Questions" from The d-and f-Block Elements→The d-and f-Block Elements — all question types→Chemistry STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

How would you account for the irregular variation of ionisation enthalpies $($first and second$)$ in the first series of the transition elements?
→
Explain boiling point and melting point of dihalo-benzene. ### Give reason why melting point of P-Dichloro benzene is more than ortho and meta isomers.
→
What are enantiomers? Draw the structures of the possible enantiomers of 3 methyl pent-1-ene.
→
What is "semi permeable membrane"?
→
Answer the following:
$(a)\ a.$ Write the mathematical relation between rate constant and half-life of a first order reaction.
$b.$ What is collision frequency?
$(b)$ If the rate equation is given below:
Rate $= k[A]^2[B]$
then what will be the unit of its rate and rate constant?
→
Determine the values of equilibrium constant $(K_C)$ and $\Delta G^{\circ}$ for the following reaction:
$\text{Ni (s)}+\text{2Ag}^{+}\text{(aq)}\rightarrow\text{Ni}^{2+}+\text{2Ag(s)},\text{E}^{\circ}=1.05\text{V}\ \ \ (\text{IF} = 96500 \text{C mol}^{–1}).$
→
Define the following terms:
  1. Fuel cell
  2. Limiting molar conductivity$(\wedge^\circ_\text{m}) $
→
What are biodegradable polymers? Write the structural formula of a biodegradable polymer.
→
Calculate the emf of the cell in which the following reaction takes place $Ni(s) + 2Ag^+ (0.002 M) \rightarrow Ni^{2+} (0.160 M) + 2Ag(s)$
Given that $\text{E}^\ominus_{(\text{cell})} = 1.05 V$
→
Consider the standard electrode potential values $\left(\frac{M^{2+}}{M}\right)$ of the elements of the first transition series.
$Ti$ $V$ $Cr$ $Mn$ $Fe$ $Co$ $Ni$ $Cu$ $Zn$
$-1.63$ $-1.18$ $-0.90$ $-1.18$ $-0.44$ $-0.28$ $-0.25$ $+0.34$ $-0.76$

Explain:
i. $E^\circ$ value for copper is positive.
ii. $E^\circ$ value of $Mn$ is more negative as expected from the trend.
iii.$Cr^{3+}$ is a stronger reducing agent than $Fe^{2+}.$
→