the helium in a 1.5L flask at 25degrees celcius exerts a pressure of 56.65kPa. How many moles of helium are in the flask?
Note the correct spelling of celsius.
Use PV = nRT
Remember T must be in kelvin.
If you use P in kPa, R must be 8.314.
To determine the number of moles of helium in the flask, we can use the ideal gas law equation, which is:
PV = nRT
Where:
P = pressure (in Pa)
V = volume (in m^3)
n = number of moles
R = ideal gas constant (8.314 J/(mol·K))
T = temperature (in Kelvin)
First, let's convert the given temperature from degrees Celsius to Kelvin:
T(K) = T(°C) + 273.15
T(K) = 25°C + 273.15 = 298.15 K
Now, let's convert the given pressure from kilopascals (kPa) to pascals (Pa):
P(Pa) = P(kPa) x 1000
P(Pa) = 56.65 kPa x 1000 = 56,650 Pa
Next, we need to convert the volume from liters (L) to cubic meters (m^3):
V(m^3) = V(L) / 1000
V(m^3) = 1.5 L / 1000 = 0.0015 m^3
Now we have all the values in the correct units, so we can substitute them into the ideal gas law equation to solve for the number of moles (n):
n = PV / RT
n = (56,650 Pa) x (0.0015 m^3) / [(8.314 J/(mol·K)) x (298.15 K)]
After calculating this expression, we will get the value of n, representing the number of moles of helium in the flask.