Potassium azide (KN3\text{KN}_3KN3) is a compound that decomposes when heated to produce potassium metal and nitrogen gas. The equation for this decomposition is:
2KN3(s)→2K(l)+3N2(g) 2\text{KN}_3(\text{s}) \rightarrow 2\text{K}(\text{l}) + 3\text{N}_2(\text{g}) 2KN3(s)→2K(l)+3N2(g)Potassium azide is used in some specialized safety gas generators to rapidly produce nitrogen gas to inflate protective bags.
A fully-inflated gas bag has a total volume of 72 dm372\text{ dm}^372 dm3. Calculate the amount of nitrogen, in moles, in this fully-inflated bag. (Assume that the volume of one mole of nitrogen under these conditions is 24 dm324\text{ dm}^324 dm3.)
Use your answer to (a)(i) to calculate the mass, in grams, of potassium azide required to produce 72 dm372\text{ dm}^372 dm3 of nitrogen. [Relative atomic masses: K=39\text{K} = 39K=39, N=14\text{N} = 14N=14]
The gas generator also contains iron(III) oxide (Fe2O3\text{Fe}_2\text{O}_3Fe2O3). This reacts with the potassium formed in the decomposition of potassium azide. The equation for the reaction is:
6K(l)+Fe2O3(s)→3K2O(s)+2Fe(s) 6\text{K}(\text{l}) + \text{Fe}_2\text{O}_3(\text{s}) \rightarrow 3\text{K}_2\text{O}(\text{s}) + 2\text{Fe}(\text{s}) 6K(l)+Fe2O3(s)→3K2O(s)+2Fe(s)Suggest one reason why the designers of the gas generator want this reaction to occur.
The generator also contains silicon dioxide (SiO2\text{SiO}_2SiO2) which reacts with the potassium oxide (K2O\text{K}_2\text{O}K2O) produced in the reaction above to form a glassy solid potassium silicate (K2SiO3\text{K}_2\text{SiO}_3K2SiO3) that safely seals all the residue products inside. Construct a balanced chemical equation for the formation of potassium silicate from potassium oxide and silicon dioxide. Include state symbols.
Another reaction of azides is to make silver azide (AgN3\text{AgN}_3AgN3), which is used as an initiator in detonators:
AgNO3(aq)+NaN3(aq)→AgN3(s)+NaNO3(aq) \text{AgNO}_3(\text{aq}) + \text{NaN}_3(\text{aq}) \rightarrow \text{AgN}_3(\text{s}) + \text{NaNO}_3(\text{aq}) AgNO3(aq)+NaN3(aq)→AgN3(s)+NaNO3(aq)What name is given to this type of reaction?
What method would you use to remove the solid silver azide from the final reaction mixture?
