b. 6.13 moles c. 5.00 moles d. 4.38 moles 2. For the reaction 2 H2 + O2 2H2O + 5

Question

b. 6.13 moles c. 5.00 moles d. 4.38 moles 2. For the reaction 2 H2 + O2 2H2O + 572.4 kJ which of the following is NOT TRUE? a. The reaction is exothermic b. 572.4 kJ of heat are liberated for each mole of water formed c. Two moles of hydrogen react with one mole of oxygen d. 572.4 kJ of heat are liberated for each two moles of hydrogen reacted. 3. Automotive airbags inflate when sodium azide, NaN3, rapidly decomposes to its constituent elements according to the chemical equation, 2 NaN 3 2 Na + 3 N2. How many grams of nitrogen are produced when 1000. milligrams of sodium azide decomposes? a. 0.01538 grams b. 0.2308 grams c. 0.3538 grams d. 0.6462 grams

Explanation / Answer

2)

Answer: b

Correct statement should be

572.4 KJ of heat are liberated for each two moles of water formed

3)

Molar mass of NaN3 = 1*MM(Na) + 3*MM(N)

= 1*22.99 + 3*14.01

= 65.02 g/mol

mass of NaN3 = 1000 mg = 1 g

mol of NaN3 = (mass)/(molar mass)

= 1/65.02

= 0.0154 mol

From balanced chemical reaction, we see that

when 2 mol of NaN3 reacts, 3 mol of N2 is formed

mol of N2 formed = (3/2)* moles of NaN3

= (3/2)*0.0154

= 0.0231 mol

Molar mass of N2 = 28.02 g/mol

mass of N2 = number of mol * molar mass

= 0.0231*28.02

= 0.6462 g

Answer: 0.6462 g

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