CHEM 1110 Lecture Notes - Lecture 5: Ethylene Glycol, Mole Fraction, Sodium Bicarbonate
31 Jan 2017
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Concentration expression are ratio of amount of solute to amount of solvent or solution. Molarity: moles of solute in a liter of solution. Ex: 3. 5% sodium chloride contains 3. 5 grams nacl in 100 grams of solute. Parts per million (ppm)= (mass of solute/mass of solution)x10^6. 300 ppm nacl contains 300 grams nacl in 10^6 grams of solution. Moles of solute per kilogram of solvent. Ex: . 2 mol of ethylene glycol in 2/0x10^3 g (2 kg) has molality of . 1m. 1 m solution of cacl2 contains 1 mole of cacl2 in each liter. Dilution doesnt change m# moles of solute. Moles of component substance divided by total moles of solution: moles of solute. Xa=(moles of substance a)/(total moles of solution) Ex: which can be made using only mass measurements. Vp of solvent above solution is lower than vp of pure solvent. Add nonvolatile solute: reduces rate of vaporization, decreasing amount of vapor. Solute particles replace some solvent molecules at the surface.
