Which of the following is NOT true about the thermodynamic standard state?
A. A solid is in its standard state when the atmospheric pressure is 1.00 atm and the temperature is 25C.
B. A pure liquid is in its standard state at 25C and a vapor pressure of 1.00 atm.
C. An aqueous solution is in its standard state at a concentration of 1.00 M.
D. A gas is in its standard state when its pressure is 1.00 atm and its temperature is 25C.
E. All of these are true.
I am left between B and C. For B i couldn't find the VP of water to be 1.00atm. I don't know anything about C.
C is correct. 1 M concn is the standard state for solutions. B is not true. A pure liquid need NOT have a vapor pressure of 1 atm. If it's a pure liquid, then it has its normal vapor pressure at 25 degrees C.
Some notes here, which probably were not meant to apply to this problem but may be worth mentioning, anyway, are as follows:
The concn of 1.00 molar ACTUALLY is an ACTIVITY of 1.00.
I understand that the IUPAC changed the standard pressure from 1 atmosphere to 1 bar (exactly 100 kPa) in 1990. As far as I know, most everyone in the US still uses 1 atm. That sorta like the STP and SATP. SATP haven't caught on in the US yet, at least not widely.
Under those added rules, there are several statements above not true; however, I think the question was meant to be more elementary than that.
If nitrogen gas is 0.10 atm, hydrogen gas is 0.50 atm, and oxygen gas is 1.00 atm. What is the partial pressure of the three gases?
The correct answer is B. A pure liquid is NOT in its standard state at 25C and a vapor pressure of 1.00 atm.
In the thermodynamic standard state, a pure liquid is generally considered to be at its standard state when its pressure is 1.00 atm and its temperature is the normal boiling point. The vapor pressure of a pure liquid at its standard state is typically less than 1.00 atm.
For option C, an aqueous solution can be considered to be in its standard state when it has a concentration of 1.00 M. This means that 1 mole of solute is dissolved in 1 liter of solvent at standard state conditions.
To determine which statement is NOT true about the thermodynamic standard state, let's examine each option.
A. A solid is in its standard state when the atmospheric pressure is 1.00 atm and the temperature is 25°C.
This statement is correct. The standard state for a solid is typically defined as the pure substance at a pressure of 1.00 atm and a temperature of 25°C.
B. A pure liquid is in its standard state at 25°C and a vapor pressure of 1.00 atm.
This statement is NOT true. The standard state for a pure liquid is typically defined at its normal boiling point, not at 25°C and a vapor pressure of 1.00 atm. The vapor pressure of a liquid varies depending on its temperature and molecular properties.
C. An aqueous solution is in its standard state at a concentration of 1.00 M.
This statement is also NOT true. The standard state for an aqueous solution is typically defined as a concentration of 1.00 M, but it is not the only condition for a solution to be in its standard state. Other factors, such as temperature and pressure, also come into play.
D. A gas is in its standard state when its pressure is 1.00 atm and its temperature is 25°C.
This statement is correct. The standard state for a gas is typically defined at a pressure of 1.00 atm and a temperature of 25°C.
E. All of these are true.
This option is not the correct answer because statement B and C are not true, as explained earlier.
Therefore, the correct answer is option B. A pure liquid is not in its standard state at 25°C and a vapor pressure of 1.00 atm.