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session.masteringchemistry.c a previous 5 of 17 | next Submit My Answers Give Up Correct o convert cts in chemical Significant Figures Feedback: Your answer 70 g NHs was either rounded differently or used a different number of significant figures than required for this part elationships lanced reaction ometry can be or number of , as shown in re 1) Part C How many grams of H2 are needed to produce 10.81 g of NH, ? Express your answer numerically in grams. Hints g H2 Submit My Answers Give Up Part D How many molecules (not moles) of NHs are produced from 2.69*104 g of H3? Express your answer numerically as the number of molecules. molar mass Hints from anced equation molar mass molecules Submit My Answers Give Up Provide Feedback Continue

Explanation / Answer

C)

Molar mass of NH3 = 1*MM(N) + 3*MM(H)

= 1*14.01 + 3*1.008

= 17.034 g/mol

mass of NH3 = 10.81 g

mol of NH3 = (mass)/(molar mass)

= 10.81/17.034

= 0.6346 mol

we have the Balanced chemical equation as:

N2 + 3 H2 —> 2 NH3

From balanced chemical reaction, we see that

when 2 mol of NH3 forms, 3 mol of H2 is required

mol of H2 required = (3/2)* moles of NH3

= (3/2)*0.6346

= 0.9519 mol

Molar mass of H2 = 2.016 g/mol

mass of H2 = number of mol * molar mass

= 0.9519*2.016

= 1.92 g

Answer: 1.92 g

D)

Molar mass of H2 = 2.016 g/mol

mass of H2 = 2.69*10^-4 g

mol of H2 = (mass)/(molar mass)

= 2.69*10^-4 /2.016

= 1.334*10^-4 mol

From balanced chemical reaction, we see that

when 3 mol of H2 reacts, 2 mol of NH3 is formed

mol of NH3 formed = (2/3)* moles of H2

= (2/3)*1.334*10^-4

= 8.895*10^-5 mol

number of molecules of NH3 = moles of NH3 * Avogadro’s number

= 8.895*10^-5 mol * 6.022*10^23 molecules/mol

= 5.36*10^19 molecules

Answer: 5.36*10^19 molecules

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