Chemistry (gas)

Question

8. Besides using NaN3, there are a number of chemical reactions that produce N2 gas. One such example is,

NH4ClO4(s) + heat = N2(g) + Cl2(g) + O2(g) + H2O(l)

a) How many grams of ammonium perchlorate would you need to produce enough nitrogen gas to exactly fill a 67.2 L air-bag under standard conditions? (Hint: Begin by balancing equation.) (3 marks)

b) Would it be a good idea to use ammonium perchlorate in commercial airbags? Explain.

(1 mark)

Answer 1

Hi Zoe B.,

To balance the equation, start counting up atoms. Start with the first element in the first reactant. Here it's one N. So you need to first write a coefficient of 2 in front of the ammonium perchlorate. That balances the N's. Then go on to the second element, etc.

If you have to adjust further the coefficient of a material that you've already adjusted, then you'll need to check forward and backwards in the reaction to make sure that everything is re-balanced.

When you're done, the atoms of each element will balance on each side of the reaction.

So to do the rest of (a), convert that N2 volume into moles, using the Universal Gas Equation. Since the balanced equation describes a ratio among moles of reactants, you may use the proportion of the coefficients of N2 and ammonium perchlorate to calculate across into moles of ammonium perchlorate required, then convert that back into mass of ammonium perchlorate.

(b) Commercial airbags are designed to deflate rapidly after cushioning your body following an impact. Therefore, the product gases are available for breathing, inside your car, as you recover from the shock of the collision. Nitrogen, oxygen, and water are no big problem, so what remains and IS a big problem?

Disclaimer: Even NaN3-powered airbags are no joke after deployment. They definitely save lives, but may cause contact burns and temporary lung irritation and exacerbate existing airway problems or even initiate them. After a collision in which the airbags activate, turn off the car's ignition, wiggle yourself for broken bones, and crank open a window if possible. Then check others in the car, scan for safely exiting the car, etc.

-- Cheers, -- Mr. d.