Tag: reactivity series and electrochemistry

Questions Related to reactivity series and electrochemistry

Out of $Cu, Ag, Fe$ and $Zn$, the metal which can displace all others from their salt solution is:

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $Ag$

  2. $Cu$

  3. $Fe$

  4. $Zn$

Show answer
Correct Option: D
Explanation:

This answer can be explained by Reduction potential values:

$Zn^{+2}+2e^- \longrightarrow Zn$  $[-0.76]$
$Ag^++e^- \longrightarrow Ag$         $[0.22]$
$Cu^++e^- \longrightarrow Cu$        $[0.52]$
$Fe^{+3}+e^- \longrightarrow Fe^{+2}$   $[0.77]$
As the reduction potential for $Zn$ is low it can replace that element from their compound state for which their reduction potential is above than that.

$H^{+}$ ions are reduced at platinum electrode prior to__________.

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $Zn^{2+}$

  2. $Cu^{2+}$

  3. $Ag^{+}$

  4. $I _{2}$

Show answer
Correct Option: A
Explanation:

$H^+$ ions are reduced at platinum electrode prior to $Zn^{2+}$.

Because reduction potential of $\underset {(aq.)}{Zn^{+2}}+2e^- \longrightarrow Zn (s)$  $(-0.76)$
It means that it favours for oxidation rather than reduction.
Where reduction potential of $\underset {(aq.)}{2H^+}+2e^- \longrightarrow H _2 (g)$         $ (0)$
                                                  $\underset {(aq.)}{Cu^{+2}}+2e^- \longrightarrow Cu (s)$     $(0.16)$
                                                  $\underset {(aq.)}{Ag^+}+e^- \longrightarrow Ag(s)$         $(0.22)$
                                                  $\underset {(s)}{I _2}+2e^- \longrightarrow \underset {(aq.)}{2I^-} $               $(0.54)$

Which one of the following four metals would be displaced from the solution of its salts by other three metals?

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $Mg$

  2. $Ag$

  3. $Zn$

  4. $Cu$

Show answer
Correct Option: B
Explanation:

In a displacement reaction, a more reactive metal of the activity series can displace a less active one in its salt solution. Reactivity order is: 
$Mg> Zn> Cu> Ag.$
Thus, we see that Ag is least reactive and of the given four metals, Ag would be displaced from the solution of its salts by other three metals.

A gas $Cl _{2}$ at $1\ atm$ is bubbled through a solution containing a mixture of $1\ M\ Br^{-1}$ and $1\ M\ F^{-1}$ at $25^{\circ}C$. If the reduction potential is $F > Cl > Br$, then

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $Cl$ will oxidise $Br$ and not $F$

  2. $Cl$ will oxidise $F$ and not $Br$

  3. $Cl$ will oxidise both $Br$ and $F$

  4. $Cl$ will reduce both $Br$ and $F$

Show answer
Correct Option: A

What happens when a piece of aluminium metal is added to dilute hydrochloric acid?

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. Aluminium displaces hydrogen

  2. Aluminium chloride is formed along with dilute hydrochloric acid

  3. Hydrogen gas is evolved

  4. No reaction

Show answer
Correct Option: A,C
Explanation:

On adding aluminium(Al) to dilute hydrochloric acid(HCl), the following displacement reaction takes place:
$2Al(s)  +  6HCl(aq)  \rightarrow   2AlCl _{3}(aq)  +  3H _{2}(g)$
Aluminium being more reactive than hydrogen, displaces the latter in hydrochloric acid $(HCl)$ to form aluminium chloride($AlCl _{3}$).

Copper sulphate solution can be safely kept in a vessel made of :

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. platinum

  2. lead

  3. silver

  4. zinc

Show answer
Correct Option: A,C
Explanation:

Silver and platinum are less reactive than copper. Hence, they can't displace copper from its solution.

The correct order of increasing chemical reactivity is :

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. $Zn < Fe < Mg < K$

  2. $Fe < Mg < Zn < K$

  3. $Fe< Mg < K < Zn$

  4. $Fe < Zn < Mg < K$

Show answer
Correct Option: D
Explanation:

The reactivity series is a series in which metals are arranged in decreasing order of their reactivities.
$Fe<Zn<Mg<K$
In the reactivity series, the most active metal is at the left side of the series and the least active metal is at the right side of the series.

Which of the following metals can displace the other three metals from their salt solutions?

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. Iron

  2. Copper

  3. Zinc

  4. None of the above

Show answer
Correct Option: D
Explanation:

Zinc is present above iron and copper in the activity series so it can displace both iron and copper from the salt solution. but question mention about other 3 so answer is none of these.

Zinc sulphate forms a colourless solution in water. Colour on adding copper  is :

chemistry reactivity series and electrochemistry reactivity series and displacement reactions chemical properties of metals chemical properties of metals and non metals

  1. blue

  2. black

  3. brown

  4. no change in colour

Show answer
Correct Option: D
Explanation:

There will be no change in colour as copper(Cu) is less reactive metal than zinc(Zn) and thus cannot displace the latter from $ZnSO _{4}$ solution.