3) Tarnished silver contains Ag2S. The tarnish can be removed by placing silverware in an aluminum pan containing an inert electrolyte Such as NaCl. Explain the electrochemical principle for this procedure. The standard reduction potential for the half-cell reaction: Ag2S (s) + 2e-  2Ag (s) + S-2 (aq) is -0.71 V

Tarnished silver ware is cleaned by placing it in an aluminium pan as E°cell is positive.

Explanation:

The tarnish silver due to silver sulphate is removed by placing the tarnished ware in an aluminium pan. Certainly, aluminium is a stronger reducing agent than silver. Hence, it reduces the silver ions(Ag+) to metallic silver. The silvery white white colour will slowly get deposited on the walls of silwer ware and then the tarnish will be removed.

Al(s)+ 3Ag+ (aq)→ Al3+ (aq)+ 3Ag(s)

E° cell = E ° cathode - E° anode

 = (-0.71)- (-1.66) = 0.95 V is positive.

Hence, the reaction is feasible and the tarnish will be removed.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

answer

fusion: the energy source of stars. the energy released from the collapse of the gas into a protostar causes the center of the protostar to become extremely hot. when the core is hot enough, nuclear fusion commences. fusion is the process where two hydrogen atoms combine to form a helium atom, releasing energy.

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