# The vapor pressure of water at 45.0 °C is 71.93 mmHg. What is the vapor pressure of water over a solution prepared from 75.0 g of citric acid (C6H8O7) in 0.420 kg of water at this temperature?

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1. PH2O> = XH2O>*o</supH2O
mols H2O = g/molar mass = 420/18 = ?
mols C6H8O7 = g/molar mass = 75.0/192 = ?
Total mols = mols H2O + mols C6H8O7 = ?
XH2O</sub = mols H2O/total mols
Calculate mols H2O, mols C6H8O7, total mols, then XH2O
Substitute into equation 1 and solve.
Post your work if you get stuck.

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2. Let me try again. I tried to type in subscripts and superscripts and that didn't work well because I didn't do it right. I think you can interpret this OK. If not let me know.
PH2O = XoH2O
mols H2O = g/molar mass = 420/18 = ?
mols C6H8O7 = g/molar mass = 75.0/192 = ?
Total mols = mols H2O + mols C6H8O7 = ?
XH2O = mols H2O/total mols
Calculate mols H2O, mols C6H8O7, total mols, then XH2O
Substitute into equation 1 and solve.
Post your work if you get stuck.

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3. Sorry again. Replace equation 1 with the following:
PH2O = XH2O*Psup>oH2O

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4. those closing tags are a pain, right? :-(

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5. A REAL pain.

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