Molarity and Dilutions Intro to Solutions Molarity and Dilutions

Solution Vocabulary Solutions are homogeneous mixtures. Solvent. Uniform throughout. Solvent. Determines the state of matter in which the solution exists. Is the largest component. Solute. Other solution components said to be dissolved in the solution.

Concentration of a Solution Measure of the amount of solute that is dissolved in a given quantity of solvent Dilute Solution: Contains a small amount of solute Concentrated Solution: Contains a large amount of solute

Ways to Describe Solution Concentration Mass/Volume Percent. Isotonic saline is prepared by dissolving 0.9 g of NaCl in 100 mL of water and is said to be: 0.9% NaCl (mass/volume) Volume percent. 100-mL of Vinegar contains 5-mL of Acetic Acid; 5% HC2H3O2 solution

ppm, ppb, and ppt Very low solute concentrations are expressed as: ppm: parts per million (g/g, mg/L) ppb: parts per billion (ng/g, g/L) ppt: parts per trillion (pg/g, ng/L) g = microgram (1 X10-6 g) ng = nanogram (1 X10-9 g) pg = picogram (1 X10-12 g)

Molarity (concentration) Molarity (M): the number of moles of solute dissolved in one liter of solution

Examples of Molarity 1. A solution has a volume of 2.0-L and contains 36.0-g of glucose (C6H12O6). What is the molarity of the solution?

Examples of Molarity 2. A solution has a volume of 250 mL and contains 0.70 mol NaCl. What is its molarity?

Examples of Molarity 3. Calculate the molarity of a solution prepared by dissolving 1.56-g of gaseous HCl in enough water to make a 26.8-mL of solution?

Dilutions Water is added to a concentrated solution to decrease the molarity. Moles of solute after dilution = moles of solute before dilution M1V1 = M2V2 M1 = Molarity concentrated solution V1 = volume of concentrated solution M2 = Molarity diluted solution V2 = Volume diluted solution

Dilution Example 1. What volume of 16 M sulfuric acid must be used to prepare 1.5 L of a 0.10 M H2SO4?