Pls. help with this chem. question.?

Question

If a 156-g of block of dry ice, CO2, is cublimed at 25 degrees celsius and 740 mm hg, what volume does the gas occupy?

Answer 1

PV=nRT

P = pressure ( atm)
V = volume (L)
n = number of moles = weight (g) / formula weight(g/mole)
R = gas constant = 0.0821 L atm/ mole degrees K
T = Temperature (Kelvin)

Now we can solve your problem.

PV=nRT
Rearrange this equation to get,
V = nRT/P

Before you do anything further, find the value of n and also make sure all the units are right according to the equation.

n = 156 (g) / 44 (g/mole) [ 44 is the formula wieght of CO2]
we get n= 3.545

T = 25 degrees celsius = 273.15 + 25 = 298.15 degree kelvin

P = 740mm Hg.

760mm Hg= 1 atm

Therefore 740 /760 = 0.9734 atm

Now use the rearranged equation,

V = nRT/P

V (Litres) = (3.545 * 0.0821*298.15) / 0.9734

V (Litres) = 89.15 litres

Answer 2

Quite a bit.
To get the answer, you need PV=nRT with these inputs. P=(740/760) atm
n= 156 x 453 g/lb / 44 g/g-mole
T= 298 K
R= 0.081 atm-L/deg K-gmole
(if you have a "R" for mm Hg, you can use it, but make sure P=740 mm Hg)
Cheating a bit, you have about 1600 g-moles.
At the P and T, 1 g-mole occupies about 25 L
So answer should be about 40000L. This is a good check on your more exact calcs.

Answer 3

156 * 740 / 25

Answer 4

Use PV=nRT
Determine your units for R and convert accordingly.
740mm becomes almost 1 atm
25C to K
156g/ MW CO2 to find n (number of moles)
You have everything but L in liters. plug and chug.

Answer 5

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