1- A 1.0000 gram sample of zinc metal is added to a solution containing 1.2500 g

Question

1- A 1.0000 gram sample of zinc metal is added to a solution containing 1.2500 grams of an unknown compound made of niobium, fluoride, and chloride. The reaction results in the formation of zinc fluoride, zinc chloride, and metallic niobium, When the reaction is complete, unreacted zinc remains, and this unreacted zinc is "burned off" by reaction with hydrochloric acid.After washing and drying, the mass of niobium metal recovered is 0.4900 grams.

a) calculate the experimental percentage of niobium in the original unknown compund.

b) In a separate experiment, a 4.0000gram sample of the unknown compound was found to contain 0.6406 gram of fluoride and 1.7931 gram of chloride. Determine the mass percentage of fluoride and chloride in the compound.

c) determine the empirical formula of the original unknown compound.

d) write a balanced chemical equation for the reaction of zinc with the original unknown compound.

e) assuminf that your answer to part D is correct, what is the minimun mass of zinc metal needed to react with niobium compound descrived above??

Please show work and answer all questions to get full points!! thank you!

Explanation / Answer

a) 0.4900 grams of niobium recovered / 1.2500 grams of unknown which = 39.20 percent??

b) cl: 1.7931/ 4.0000 = 44.828 percent and fl: 0.6406/4.000 = 16.02 percent

c) The 4.000g compound in b) contained 1.7931gCl and 0.6406g F
Therefore mass of Nb = 4.000 - ( 1.7931 + 0.6406) = 1.5663g Nb

Divide each mass by respective atomic mass:
Nb = 1.5663/ 92.91 = 0.016858
Cl = 1.7931/35.453 = 0.05058
F = 0.6406/18.998 = 0.0337

Divide by smallest:
Nb = 1
Cl = 3
F = 2

Empirical formula = NbCl3F2

d) the zinc must react to produce the zinc chloride and zinc fluoride, The Nb does not react

Equation: 2NbCl3F2 + 5Zn = 2Nb + 3ZnCl2 + 2ZnF2

e) Determine the mass of Zn required to react with 1.2500g NbCl3F2
From the equation:
2mol NbCl3F2 will react with 5mol Zn

Molar mass NbCl3F2 = 237.2628 g/mol
1.2500g NbCl3F2 = 1.2500/237.2628 = 0.005268mol
This will react with : 0.005268 *5/2 = 0.0132 mol Zn
Molar mass Zn = 65.38g/mol
0.0132mol = 0.0132 * 65.38 = 0.86g

Mass Zn required = 0.86g.

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