Compute the difference in masses of one mole | vedclass

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Question

(A) The molar mass of an aluminium atom is $27 \,g \,mol^{-1}$.An aluminium atom $(Al)$ loses $3$ electrons to form an aluminium ion $(Al^{3+})$.For $

Vedclass · Accepted Answer

$0.0016$

Vedclass · Answer

(A) The molar mass of an aluminium atom is $27 \,g \,mol^{-1}$.An aluminium atom $(Al)$ loses $3$ electrons to form an aluminium ion $(Al^{3+})$.For $1 \,mol$ of $Al^{3+}$ ions,$3 \,mol$ of electrons are lost.The mass of $1 \,mol$ of electrons is calculated by multiplying the mass of one electron by Avogadro's number $(N_A = 6.022 	imes 10^{23} \,mol^{-1})$.Mass of $3 \,mol$ of electrons $= 3 	imes (9.1 	imes 10^{-28} \,g) 	imes (6.022 	imes 10^{23} \,mol^{-1})$.$= 27.3 	imes 6.022 	imes 10^{-5} \,g \,mol^{-1} \approx 164.4 	imes 10^{-5} \,g \,mol^{-1} = 0.001644 \,g \,mol^{-1}$.Since the ion has lost mass (electrons),the aluminium atom is heavier than the aluminium ion by the mass of the lost electrons,which is approximately $0.0016 \,g$.

Compute the difference in masses of one mole each of aluminium atoms and one mole of its ions. (Mass of an electron is $9.1 \times 10^{-28} \,g$). Which one is heavier (in $,g$)?

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