A sample of gas is collected over water at a temperature of 45.0 oC when barometric pressure reading is 742.0 torr. What is the partial pressure of the dry gas?

This site tells me that vapour pressure of water at 35.0 ∘C = 42.2⋅mm⋅Hg.

Explanation:
P
collected
=P gas+P SVP, P SVP is given above, and is called the saturated vapour pressure. This should have been quoted with the question.

Thus
Pgas≅700⋅mm⋅Hg.

Ptotal = Pgas + PH2O.

Ptotal = 742.0
pH2O = ? Look up the vapor pressure of H2O @ 45.0 degrees C. You should have that in your text/notes or you can find it on the web. Note that Helper used 35.0 but the problem gives 45.0 C.

To find the partial pressure of the dry gas, we need to subtract the vapor pressure of water from the total pressure.

First, let's determine the vapor pressure of water at 45.0°C using a reference table or vapor pressure calculator. The vapor pressure of water at 45.0°C is approximately 71.93 torr.

Next, subtract the vapor pressure of water from the total pressure:

Partial pressure of dry gas = Total pressure - Vapor pressure of water
Partial pressure of dry gas = 742.0 torr - 71.93 torr
Partial pressure of dry gas = 670.07 torr

Therefore, the partial pressure of the dry gas is approximately 670.07 torr.

To find the partial pressure of the dry gas, we need to subtract the vapor pressure of water at the given temperature from the total barometric pressure.

First, let's find the vapor pressure of water at 45.0°C. We can use the Antoine equation, which gives the vapor pressure as a function of temperature:

log(P) = A - B/(T + C)

where P is the vapor pressure in torr, T is the temperature in degrees Celsius, and A, B, and C are constants specific to the substance. For water, the Antoine equation constants are:

A = 8.07131
B = 1730.63
C = 233.426

Plugging in the values, we have:

log(P) = 8.07131 - 1730.63/(45.0 + 233.426)

Now, we can solve for P by taking the antilog of both sides of the equation:

P = 10^(8.07131 - 1730.63/(45.0 + 233.426))

Using a calculator, we find that P ≈ 150.94 torr.

Next, we can find the partial pressure of the dry gas by subtracting the vapor pressure from the total barometric pressure:

Partial pressure of the dry gas = Barometric pressure - Vapor pressure of water

Partial pressure of the dry gas = 742.0 torr - 150.94 torr

Therefore, the partial pressure of the dry gas is approximately 591.06 torr.