Q&A for How to Calculate Vapor Pressure

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How is vapor pressure affected by temperature?

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As the temperature of a liquid or solid increases, its vapor pressure also increases. Conversely, vapor pressure decreases as the temperature decreases.

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How can I solve this problem? "The vapor pressure of pure water is 760mm at 25 degree Celsius. The vapor pressure of a solution containing 1 m of solution of glucose will be what?"

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I suggest you study colligative properties. The pressure lowering of the water is PX' as P stands for the pressure of pure solvent and X' is the molar fraction of the solute. 1L of water has 1000g of water, so there are 1000/18 mols of water ~ 55.6 mols. So, there's 56.6 mols of molecules for every 1L of solution (one comes from glucose and 55.6 from water as calculated). So, the solute molar fraction is 1/56.6 ~ 1.768.10^-2. So the pressure lowering is 760mmHg times 1.768.10^-2, which is ~ 13.44 mmHg. Finally, the vapor pressure of the solution is 760mmHg-13.44mmHg = 746.56mmHg.

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At an ambient temperature, what would be the vapor pressure of water?

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You can use the Antoine's equation to calculate the vapor pressure of any substance and any temperature. At an ambient pressure of 25 degrees Celsius, the vapor pressure of water is 23.8 torr.

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How many atoms are in a gram of carbon?

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The molar mass of carbon is 12.011 grams per mole, and in every mole there is 6.022 * 10^23 atoms. Just use these equation to calculate: (1 g) * (1 mol)/12.011 g = 1/12.011 moles = 0.083257 moles. Now, take this number, and convert moles to atoms. (0.083257 mole) * (6.022 * 10^23 atoms)/(1 mole) = 0.083257 * 6.022 * 10^23 = 5.01374 * 10^22 atoms.

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