NCERT Solutions for Class 12 Chemistry Part 1 Electrochemistry
Categories: NCERT Solutions
NCERT Solutions for Class 12 Chemistry Part 1
Electrochemistry
Q1: Why does the conductivity of a solution decrease with dilution?
Answer: The conductivity of a solution is the conductance of ions present in a unit volume of the solution. The number of ions (responsible for carrying current) decreases when the solution is diluted. As a result, the conductivity of a solution decreases with dilution.
Q2: Suggest a list of metals that are extracted electrolytically.
Answer: Metals that are on the top of the reactivity series such as sodium, potassium, calcium, lithium, magnesium, aluminium are extracted electrolytically.
Q3: Suggest two materials other than hydrogen that can be used as fuels in fuel cells.
Answer: Methane and methanol can be used as fuels in fuel cells.
Q4: Arrange the following metals in the order in which they displace each other from the solution of their salts. Al, Cu, Fe, Mg and Zn
Answer: The following is the order in which the given metals displace each other from the solution of their salts.
Mg, Al, Zn, Fe, Cu
Q5: Given the standard electrode potentials,
K + /K = -2.93V, Ag + /Ag = 0.80V,
Hg 2+/Hg = 0.79V
Mg 2+/Mg = -2.37 V, Cr 3+/Cr = - 0.74V
Arrange these metals in their increasing order of reducing power.
Answer: The lower the reduction potential, the higher is the reducing power. The given standard electrode potentials increase in the order of K + /K < Mg
2+/Mg < Cr 3+/Cr < Hg 2+/Hg < Ag + /Ag.
Hence, the reducing power of the given metals increases in the following order:
Ag < Hg < Cr < Mg < K
Q6: Can you store copper sulphate solutions in a zinc pot?
Answer: Zinc is more reactive than copper. Therefore, zinc can displace copper from its salt solution. If copper sulphate solution is stored in a zinc pot, then zinc will displace copper from the copper sulphate solution. Hence, copper sulphate solution cannot be stored in a zinc pot.
Q7: Consult the table of standard electrode potentials and suggest three substances that can oxidise ferrous ions under suitable conditions.
Answer: Substances that are stronger oxidising agents than ferrous ions can oxidise ferrous ions.
; = - 0.77 V
This implies that the substances having higher reduction potentials than
+0.77 V can oxidise ferrous ions to ferric ions. Three substances that can do so are F2, Cl2, and O2.