First, let's convert all the pressures to the same unit. We will use torr since one of them is already in torr.
1 atm = 760 torr, so 0.300 atm = 0.300 * 760 = 228 torr.
Now we have:
He(g): V = 1.25 L, P = 228 torr
Ar(g): V = 2.50 L, P = 233 torr
When the stopcock between the flasks is opened, the gases will mix and the final pressure can be found using the formula for partial pressures:
P_total = P_He + P_Ar
To calculate the partial pressures, we first need the total volume:
V_total = V_He + V_Ar = 1.25 L + 2.50 L = 3.75 L
Now we have to find the moles of each gas using the ideal gas law equation, PV = nRT. We'll assume a constant temperature and use R = 62.36 L * torr / mol * K since we're using torr and L.
He(g): 228 torr * 1.25 L = n * 62.36 L * torr / mol * K
n_He = 228 * 1.25 / 62.36 = 4.583 moles
Ar(g): 233 torr * 2.50 L = n * 62.36 L * torr / mol * K
n_Ar = 233 * 2.50 / 62.36 = 9.324 moles
Now, we can use the total volume and total moles to find the new pressure after the gases mix:
P_total * 3.75 L = (4.583 + 9.324) * 62.36 L * torr / mol * K
P_total = (4.583 + 9.324) * 62.36 / 3.75 = 242.40 torr
The total pressure after the stopcock is opened and the gases mix is approximately 242.40 torr.
Consider the flasks diagrammed below. What is the total pressure in torr after the stopcock between the two flasks is opened? He(g)---> V=1.25L and P=0.300atm and Ar(g)---> V=2.50L and P=233 torr.
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