107.9 g of Ag is produced from a reaction of 31. 75 gram of Copper.
<h3>How we calculate mass from the moles?</h3>
Mass of any substance will be calculated from its moles as:
n = W/M, where
W = required mass
M= molar mas
Given chemical reaction is:
Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag
From the stoichiometry of the reaction, it is clear that:
1 mole of Cu = produce 2 moles of Ag
Given mass of Cu = 31.75g
Molar mass of Cu = 63.5g/mol
Moles of Cu = 31.75g / 63.5g/mol = 0.5 moles
0.5 moles of Cu = produce 2×0.5 = 1 mole of Ag
Molar mass of Ag = 107.9g/mol
Required mass of Ag = 1mol × 107.9g/mol = 107.9 g
Hence, option (2) is correct i.e. 107.9 g of Ag is produced.
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