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1. When 0.75 g of hydrazine, NJ?H, decomposes, the mass of hydrogen produced sho

ID: 705116 • Letter: 1

Question

1. When 0.75 g of hydrazine, NJ?H, decomposes, the mass of hydrogen produced should be,L (A) equal to 0.75 g because mass is conserved. (B) equal to twice the mass of the nitrogen because of stoichiometry (C) less than the mass of nitrogen because of relative molecular weights.- (D) greater than the mass of hydrazine because more moles of hydrogen are produced. 2. Which chemical reaction could be represented by the figure below? (A) CH4 + 2 Cl2 ? CCl4 + 2H2 (B) NH3 + 202 NO2 2 H20 (C) CH4 + 202 ? CO2 + 2H3O (D) NH4 2 Cl2 NC12 2 H20 3. Which picture below represents a heterogeneous mixture?

Explanation / Answer

ANSWER (1) :- Option (C) is correct

N2H4 --> N2 + 2H2 so 1 mole hydrazine produces 1 mole nitrogen gas and two moles hydrogen gas.
0.75 g / 32.0452 g/mol = 0.0234 moles hydrazine so 0.0234*2 = 0.0468 moles N2 and 0.0234 moles H2
are produced. Mass N2 = 0.0468 mol * 28.014 g/mol = 1.31 g, Mass H2 = 0.0234 mol * 2.0 g/mol = 0.0468 g.

SO, the right answer is (C). H2 produced is less than N2 because N2 has a much greater molar mass than H2.