please help with chemistry, it is the only problem i cant figure out and my teacher wont help...?

Question

thanks alot to anyone who can show me how to do it or tell me an answer....

As shown in the image above a sample of sodium bicarbonate is heated, producing oxygen gas. The volume of gas collected is 260.mL at 21.0 degrees C and 760.0 Torr of total pressure. How many moles of carbon dioxide are produced?


i dont think the image really matters in the problem, the gas is just being collected in a glass container...thanks!

Answer 1

Use the ideal gas law, and solve for moles of gas

PV=nRT

n = PV/RT

substitute in your variables:

change V to L
260 ml = 0.26 L

change temp to K
21 C=294.15 K

use 62.3637 L · Torr · K-1 · mol-1 for R
because your pressure in is torr

n = [(760 Torr)(0.26 L)]/[(62.3637 L · Torr · K-1 · mol-1)(294.15 K)]

n= 1.08 x 10^-2 moles

Answer 2

The answer to this problem can simply be found using the Ideal Gas Law formula PV=nRT. The pressure is the 760.0 Torr, the volume is 260mL converted to Liters, n is the number of moles you are looking for, R is the gas constant 0.0821, and the Temperature is degrees C converted to Kelvins (21+273). So you preceed as follows:

First, I would convert mL to L 260*(1*10^(-3))=.26 Liters
so u have 760=1 atm for pressure
so now plug everything back in:
(1 atm)(.260 L)=N(.0821)(294 K)
.260 L/24.1374=N
N= ~1.077*10^(-2) moles

I hope this helps you!

Answer 3

Use the fact that one Mole of Gas is 22.4 Liters at STP. 760 Torr is Standard Pressure, but I don't think that 21C is standard Temperature. You will need to convert the volume to the standard Temperature equivalent. This will give you the number of Moles of O2 Gas. Then you will need to use your reaction equation to see how much CO2 is produced for a Mole of O2.

Good Luck.