So here I am doing my HW worksheet on the ideal gas law/graham's law ad I have gotten to this one problem where I am totally stuck and confused. Please help me by telling me how to set this up and giving me tips, if necessary.
What is the mass (in grams) of ammonia gas (NH {tiny #3at the bottom}, 17g/mole contained in a 4.00 flask at 32.5 degrees Celsius and 1.6atm?
Answered below.
So is grams, n in the formula PV=nRT?
I think I am starting to understand this.
No. n in the formula PV = nRT is the number of moles.
First you solve for n (number of moles). THEN you use the formula, moles = grams/molar mass to solve for grams (which is what the problem asks for).
Oh! I think I understand now
To solve this problem, you can use the ideal gas law equation, which is:
PV = nRT
Where:
P = pressure (in atmosphere, atm)
V = volume (in liters, L)
n = number of moles
R = ideal gas constant (0.0821 L·atm/(mol·K))
T = temperature (in Kelvin, K)
Since you're given the pressure, volume, temperature, and the molecular weight (molar mass) of ammonia, you can use the ideal gas law equation to determine the number of moles of ammonia gas, and then convert it to grams using its molar mass.
Here are the steps to solve the problem:
Step 1: Convert Celsius to Kelvin.
To convert the temperature from Celsius to Kelvin, add 273.15 to the given temperature:
32.5°C + 273.15 = 305.65 K
Step 2: Apply the ideal gas law equation to find the number of moles.
PV = nRT
1.6 atm x 4.00 L = n x 0.0821 L·atm/(mol·K) x 305.65 K
Solving for n:
n = (1.6 atm x 4.00 L) / (0.0821 L·atm/(mol·K) x 305.65 K)
Step 3: Calculate the number of moles.
Now, substitute the given values into the equation and calculate the number of moles:
n = (1.6 atm x 4.00 L) / (0.0821 L·atm/(mol·K) x 305.65 K)
n ≈ 0.268 moles
Step 4: Convert moles to grams using the molar mass.
The molar mass of ammonia (NH₃) is approximately 17 g/mol.
Now, multiply the number of moles by the molar mass to get the mass in grams:
Mass = n x molar mass
Mass = 0.268 moles x 17 g/mol
Mass ≈ 4.556 grams
Therefore, the mass of ammonia gas contained in the 4.00 L flask at 32.5 degrees Celsius and 1.6 atm is approximately 4.556 grams.