Nitrogen and Overall Cell Reaction

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N11/4/CHEMI/SP2/ENG/TZ0/XX

88116105

CHEMISTRY STandaRd lEvEl PaPER 2 Monday 7 November 2011 (afternoon) 1 hour 15 minutes INSTRUCTIONS TO CANDIDATES • • • • •

Candidate session number 0 0 Examination code 8 8 1 1 – 6 1 0 5

Write your session number in the boxes above. Do not open this examination paper until instructed to do so. Section A: answer all questions. Section B: answer one question. Write your answers in the boxes provided.

19 pages © International Baccalaureate Organization 2011

0120

2– SECTION A Answer all questions. Write your answers in the boxes provided. 1.

N11/4/CHEMI/SP2/ENG/TZ0/XX

Airbags are an important safety feature in vehicles. Sodium azide, potassium nitrate and silicondioxidehavebeenusedinonedesignofairbag.

[Source:www.hilalairbag.net]

Sodium azide, a toxic compound, undergoes the following decomposition reaction under certainconditions. 2NaN 3 (s) → 2Na (s) + 3N 2 (g) Twostudentslookedatdatainasimulatedcomputer-basedexperimenttodeterminethevolume ofnitrogengeneratedinanairbag. (a) Sodium azide involves ionic bonding, and metallic bonding is present in sodium. Describeionicandmetallicbonding. [2] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(This question continues on the following page)

0220

3– (Question 1 continued)

N11/4/CHEMI/SP2/ENG/TZ0/XX

(b) Usingthesimulationprogramme,thestudentsenteredthefollowingdataintothecomputer. Temperature (T ) /°C 25.00 (i) Mass of NaN3 (s) (m) / kg 0.0650 Pressure ( p) / atm 1.08 [1]

Statethenumberofsignificantfiguresforthetemperature,massandpressuredata. T: m: p: ........................................................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(ii) Calculatetheamount,inmol,ofsodiumazidepresent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

[1]

(iii) Determine the volume of nitrogen gas, in dm3, produced under these conditions basedonthisreaction. [4] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....
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