What is the % of metal (P) by mass in alloy. | TestHub

Passage / Comprehension

A silvery coloured alloy made up of two metals [P] and [Q] . 10 gram sample of that alloy dissolve in dil. HNO₃ to produce transparent clear solution-[S] .

Assume no redox change on passing H₂S in step 2 and 100% yield of the all precipitation reaction.

(Given that dmg = dimethylglyoxime , atomic mass of Zn = 65 , Cu = 63.5 , Mn = 55 , Fe = 56 , Sn = 119 , Pb = 207 , Ni = 58.6 , Au = 197 , Ag = 108 , Cd = 112.5 , Hg = 200 , Pt = 195 , Al = 27 , Co = 59 , C = 12 , H = 1 , O = 16 , N = 14 , S = 32 , Cl = 35.5)

What is the % of metal (P) by mass in alloy.

Answer:

Solution:

Molar mass of Ni(dmg)₂ = $58.6 + 2 [(4 \times 2) + (7 \times 1) + (2 \times 14) + (2 \times 16)] = 288.6 g / m o l$

Given Mass of Ni(dmg)₂ = $8.7 g$

Moles of Ni(dmg)₂ = $0.03014$

Mass of Ni = $0.03014 \times 58.6 = 1.76 g$

Total mass of copper = $10 - 1.76 = 8.24 g$

% of copper = $82.40%$

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