Which of the following is an example of how pictures of a planet's surface can provide evidence about the planet's natural resou
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Use the Clausius-Clapeyron equation...
<span>Let T1 be the normal boiling point, which will occur at standard pressure (P1), which is 101.3 kPa (aka 760 torr or 1.00 atm). You know the vapour pressure (P2) at a different temperature (T2). And you are given the enthalpy of vaporization. Therefore, we can use the Clausius-Clapeyron equation.
</span>![ln(P_1/P_2) = \frac{-\delta H_{vap}}{R} \times [\frac{1}{T_1} - \frac{1}{T_2}]](https://tex.z-dn.net/?f=ln%28P_1%2FP_2%29%20%3D%20%5Cfrac%7B-%5Cdelta%20H_%7Bvap%7D%7D%7BR%7D%20%20%5Ctimes%20%5B%5Cfrac%7B1%7D%7BT_1%7D%20-%20%5Cfrac%7B1%7D%7BT_2%7D%5D)
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</span><span>ln(101.3 kPa / 52.7 kPa) = (-29.82 kJ/mol / 8.314x10^{-3} kJ/molK) (1/T - 1/329 K)
</span>
------ some algebra goes here -----
<span>T = 349.99K ...... or ...... 76.8C </span>
<span>Let T1 be the normal boiling point, which will occur at standard pressure (P1), which is 101.3 kPa (aka 760 torr or 1.00 atm). You know the vapour pressure (P2) at a different temperature (T2). And you are given the enthalpy of vaporization. Therefore, we can use the Clausius-Clapeyron equation.
</span>
</span><span>ln(101.3 kPa / 52.7 kPa) = (-29.82 kJ/mol / 8.314x10^{-3} kJ/molK) (1/T - 1/329 K)
</span>
------ some algebra goes here -----
<span>T = 349.99K ...... or ...... 76.8C </span>
The question is incomplete, here is the complete question:
A solution contains 0.115 mol and an unknown number of moles of sodium chloride. The vapor pressure of the solution at 30°C is 25.7 torr. The vapor pressure of pure water at this temperature is 31.8 torr. Calculate the number of grams of sodium chloride in the solution. (Hint: Remember that sodium chloride is a strong electrolyte.)
<u>Answer:</u> The mass of sodium chloride in the solution is 0.714 grams
<u>Explanation:</u>
The formula for relative lowering of vapor pressure will be:
where,
= vapor pressure of solvent (water) = 31.8 torr
= vapor pressure of the solution = 25.7 torr
i = Van't Hoff factor = 2
= mole fraction of solute (sodium chloride) = ?
Putting values in above equation, we get:
Mole fraction of a substance is calculated by using the equation:
We are given:
Moles of water = 0.115 moles
To calculate the mass for given number of moles, we use the equation:
Moles of NaCl = 0.0122 moles
Molar mass of NaCl = 58.5 g/mol
Putting values in above equation, we get:
Hence, the mass of sodium chloride in the solution is 0.714 grams