Calculate how many grams of sodium azide (nan3) are needed to inflate a 25.0 × 25.0 × 20.0 cm bag to a pressure of 1.35 atm at a temperature of 20.0°c. how much sodium azide is needed if the air bag must produce the same pressure at 10.0°c? the equation is 20nan3+6sio2+4kno3=32n2+5na4sio4+k4 sio

Answer : The mass of at temperature 28.47 g.

The mass of at temperature 29.51 g.

Solution : Given,

Pressure of gas = 1.35 atm

Temperature of gas =    

Volume of gas =  

Molar mass of = 65 g/mole

Part 1 : First we have to calculate the moles of gas at temperature . The gas produced in the given reaction is .

Using ideal gas equation,

where,

P = pressure of the gas

V = volume of the gas

T = temperature of the gas

n = number of moles of gas

R = Gas constant = 0.0821 Latm/moleK

Now put all the given values in this formula, we get

By rearranging the terms, we get the value of 'n'

The moles of = 0.7015 moles

The given balanced reaction is,

As, 32 moles of produced from 20 moles of

So, 0.7015 moles of produced from moles of

Now we have to calculate the mass of .

Therefore, the mass of needed are 28.47 g.

Part 2 : We have to calculate the moles of gas at temperature and same volume & pressure.

Using ideal gas equation,

Now put all the given values in this formula, we get

By rearranging the terms, we get the value of 'n'

The moles of = 0.726 moles

The given balanced reaction is,

As, 32 moles of produced from 20 moles of

So, 0.726 moles of produced from moles of

Now we have to calculate the mass of .

Therefore, the mass of needed are 29.51 g.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.