Exactly 5.02 grams of an unknown gas was sealed in a 3.0L flask at 37 degrees celsius and a pressure of 1.25 atm. Which on of the following is most likely to be the unknown?
H2O, HBr, HCN, H2S, C2H2
ok so I did (1.25)(3.0) = n(0.0821)(310)
3.75 = n(25.451)
n=0.1473
Then I did 0.1473= 5.02/mm and I got 34.08 and this is the mm for H2S. Is this correct?
That looks ok to me.
H2O is about 18
HBr = about 80 or so
HCN is about 27
H2S is about 34
C2H2 is about 26.
Ok thank you
that is correct. The MM for Hs@ is 34.1. Closes to 5.02/0.147=34.15.
You can also use d=PM/RT. Density is mass/volume. Plug it in and solve for M.
To determine the most likely unknown gas among the given options, you need to use the Ideal Gas Law equation, PV = nRT.
First, let's rearrange the equation to solve for the number of moles of gas (n). The equation becomes n = PV / RT, where P is the pressure, V is the volume, R is the ideal gas constant (0.0821 L·atm/(mol·K)), and T is the temperature in Kelvin.
Given:
Pressure (P) = 1.25 atm
Volume (V) = 3.0 L
Temperature (T) = 37°C = 37 + 273.15 K = 310.15 K
So, plugging in the values, we have:
n = (1.25 atm x 3.0 L) / (0.0821 L·atm/(mol·K) x 310.15 K)
Calculating this, we get:
n ≈ 0.1473 moles
Now, to determine the molar mass (mm) of the gas, we can use the equation mm = mass / n, where mass is the given mass of the gas (5.02 grams).
Therefore, mm = mass / n = 5.02 g / 0.1473 mol ≈ 34.08 g/mol.
You have correctly calculated the molar mass of the unknown gas to be approximately 34.08 g/mol.
Comparing this value to the given options, the closest match is H2S (Hydrogen sulfide), which has a molar mass of approximately 34.08 g/mol. Therefore, H2S is the most likely unknown gas based on the given information.
Your calculation and approach appear to be correct.