Question

2.76gms of silver carbonate on being strongly heated yield a residue weighing
A) $2.16 gm$
B) $2.48 gm$
C) $2.64 gm$
D) $2.32 gm$

Answer 1

Hint: A mole is defined as the quantity of substance containing the same number of entities (atoms, molecules or ions) as that present in \[12{\text{ }}gms\] of ${}^{12}C$ isotope. As a gram molecular weight or gram atomic weight of a substance contains Avogadro's number of particles ($6.023 \times {10^{23}}$ atoms, molecules or ions)

 Complete step by step answer:
 silver carbonate decomposes as
$
  2A{g_2}C{O_3} \to 4Ag + 2C{O_2} + {O_2} \\
  2{\text{ }}moles\;\;\;\;\;\;\;\;4{\text{ }}moles \\
$
As per the stoichiometric equation, 2 moles of silver carbonate decomposes to leave a residue of 4 moles of silver.
2 moles of silver carbonate weighs = \[2 \times 276{\text{ }}gms\]
Number of moles of silver carbonate $
   = \dfrac{{2.76}}{{276}} \\
   = 0.01 \\
       $
Therefore, the amount of silver produced \[ = 0.01 \times 2 \times 108\] \[ = 2.16{\text{ }}gms\]
Therefore, \[2.76{\text{ }}gm\] of silver carbonate on strongly heating yields a residue weighing \[2.16{\text{ }}gm\] .
So, Option “A” is correct.

Note: The molar mass of an element is found on the periodic table, and it is the element's atomic weight in grams/mole \[g/mol\] . If the mass of a substance is known, the number of moles in the substance can be calculated. Converting the mass, in grams, of a substance to moles requires a conversion factor of one mole of substance or molar mass of substance.