Worked gas prob with my anwer +correct answer

[geffman1]

stoichiometric relationships

Homework Statement

hey guys just wondering if you could tell me where i went wrong
"One process related to formation of smog is:
2NO(g) + O2(g) 2NO2(g)
This reaction can be monitored in the laboratory by finding the total pressure of a mixture of the gases.

A bulb of volume 1.000 L is filled with a mixture of NO(g) and O2(g). The initial total pressure is 335 kPa at 26.4°C. After 6 hours the total pressure is 263 kPa. What mass of NO2(g) in grams has been formed? "

PV=nRT
P=335Kpa-263Kpa=72Kpa
R=8.314
v=1
t=299.4K

n=PV/RT=72/(8.314*299.4)=0.0289
Therefore mass =moles*molermass=0.0289*46.01=1.33grams HOWEVER answer is 2.66grams? therefore i should mulitple my answer by 2, but Y?
anyhelp would be apprecitated

Homework Equations

The Attempt at a Solution

 

[Borek]

If I understand what you did correctly, 72 kPa is amount of oxygen that reacted - take a look at the reaction equation now...

 

[Blueshift5]

Thank you for sharing your work and providing the correct answer. It seems that you have correctly applied the ideal gas law to calculate the moles of NO2 formed. However, the reason why you need to multiply your answer by 2 is because of the stoichiometric relationship between the reactants and products in the given reaction.

In this reaction, for every 2 moles of NO used, 2 moles of NO2 are produced. This means that the amount of NO2 formed will be double the amount of NO used. Therefore, you need to multiply your calculated moles of NO2 by 2 to get the correct answer.

In general, when solving stoichiometric problems, it is important to consider the balanced chemical equation and the stoichiometric ratios between the reactants and products. This will ensure that your calculations are accurate and your answer is correct.

I hope this helps clarify why your answer needs to be multiplied by 2. Keep up the good work!