InterviewSolution
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What is the mass of precipitate formed when50 mL of 16.9% solution of AgNO3 is mixedwith 50 mL of 5.8% NaCl solution?(Ag = 107.8,N = 14,0 = 16,Na 23,Cl 35.5)(a) 28 g (b) 3.5 g (c)7g (d) 14 g |
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Answer» Well,w/v≡Mass of soluteVolume of solution, we should get over7⋅gof silver chloride. Explanation: And thusmass of silver nitrate=16.9%×50⋅mL=8.45⋅g. And this represents a molar quantity of8.45⋅g/169.87⋅g⋅mol−1 =0.0497⋅mol, with respect toAgNO3. Likewisemass of sodium chloride=5.8%×50⋅mL=2.90⋅g. And this represents a molar quantity of2.90⋅g/58.44⋅g⋅mol−1 =0.0497⋅molwith respect toNaCl. Clearly the reagents are present in 1:1 molar ratio. The reaction that occurs in solution is the precipitation of a curdy white mass ofAgCl(s), i.e. and we represent this reaction by the net ionic equation..... Ag++Cl−→AgCl(s)⏐↓ Of course the complete reaction is.... AgNO3(aq)+NaCl(aq)→AgCl(s)⏐↓+NaNO3(aq), i.e. sodium nitrate remains in solution and can be separated (with effort) from the precipitate. And given thestoichiometry, we gets, 0.04974⋅mol×143.32⋅g⋅mol−1=7.11⋅g. Of course a material such as silver halide would be very hard to isolate. Particle size is very small; it is likely to clog the filter, and filter very slowly; and moreoverAgClis photoactive, and would decompose under light. |
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