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Airbags are an important safety feature of today’s cars - VCE - SSCE Chemistry - Question 15 - 2011 - Paper 1

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Airbags are an important safety feature of today’s cars. The airbag contains a mixture of solid sodium azide, NaN₃, and potassium nitrate, KNO₃. In the event of an a... show full transcript

Worked Solution & Example Answer:Airbags are an important safety feature of today’s cars - VCE - SSCE Chemistry - Question 15 - 2011 - Paper 1

Step 1

Calculate the number of moles of gas produced

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Answer

To find the number of moles, use the Ideal Gas Law:

PV=nRTPV = nRT

Where:

  • PP = pressure in pascals (100 kPa = 100,000 Pa)
  • VV = volume in liters (62.0 L = 0.062 m³)
  • RR = ideal gas constant (8.314 J/(mol·K))
  • TT = temperature in Kelvin (36.6 °C = 309.75 K)

Rearranging gives:

n=PVRTn = \frac{PV}{RT}

Calculating: n=(100000)(0.062)(8.314)(309.75)=2.43extmolesofNn = \frac{(100000)(0.062)}{(8.314)(309.75)} = 2.43 ext{ moles of } N

Step 2

Determine the moles of sodium azide required

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Answer

From the balanced equation, 10 moles of NaN₃ produce 16 moles of N. Thus, the moles of NaN₃ needed are:

1016×2.43=1.52extmolesofNaN3 \frac{10}{16} \times 2.43 = 1.52 ext{ moles of } NaN₃

Step 3

Calculate the mass of sodium azide

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Answer

Using the molar mass of NaN₃ (65.0 g/mol), the mass can be found as:

mass=moles×molarmass=1.52×65.0=98.8gmass = moles \times molar mass = 1.52 \times 65.0 = 98.8 g

Rounding gives approximately 97.9 g, hence the answer is:

  • C. 97.9 g

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