1. Solutions Day 2 Chemistry Ms. Boon 11.28.12

2. Catalyst  Identify the following substances as homogeneous mixtures or heterogeneous mixtures:  Milk  Gasoline  Muddy water  Steel  Coffee  Ink  Crude oil  Bronze  Brass  seawater Objective Agenda  Catalyst  Homework review  Percent concentration  Exit slip  I can express the concentration of a solution by percent concentration. HW: Read pp. 460-464, 468-470 Problems pp. 488 #4, 16, 21, 25

3. Homework Review: pp. 459 3.The solvent is the substance in excess. There is more of it. The solute is the substance dissolved in the solvent. 4.(a) solvent: water; solute: carbon dioxide (b) solvent: water; solute: apple extract (c) solvent: water; solute: coffee filtrate (d) solvent: water; solute: salt 5.No. A solution is any homogeneous mixture and can be gas & gas or solid & solid. (example: air or brass) 12. Water is evaporating, leaving behind the solute which is salt.

4. Solutions Mini-Review A solution is a homogeneous mixture. In a solution, the solute is distributed evenly throughout the solvent.

5. Solutions Mini-Review Therefore, any part of a solution has the same ratio of solute to solvent as any other part of the solution. This ratio (or comparison) of solute to solvent is called concentration.

6. Percent Concentration One way to express concentration is by using a percentage. Percentage concentration is the number of grams of solute per 100 grams of solution. % concentration = g solute___ x 100% g solution Example: Roundup weed killer is a solution containing 18% chemical pesticide. There are 18 g pesticide for every 100 g solution.

7. Finding the Percent Concentration % concentration = g solute___ x 100% g solution The denominator is the mass of solution. Add: g solute + g solvent Example 1: What is the percentage by mass of a solution made by dissolving 0.5 g of glucose in 9.5 g of water?

8. Finding the Percent Concentration % concentration = g solute___ x 100% g solution The denominator is the mass of solution. Add: g solute + g solvent Example 2: What is the percentage by mass of a solution containing 12.70 g of water and 0.49 g of potassium sulfate (K 2 SO 4 )?

9. Finding the Percent Concentration % concentration = g solute___ x 100% g solution The denominator is the mass of solution. Add: g solute + g solvent Example 3: What is the percentage by mass of a salt water solution made by dissolving 0.5 mol NaCl in 500 g water? The units must be grams. If given moles, multiply by the molar mass.

10. Finding the Percent Concentration % concentration = g solute___ x 100% g solution The denominator is the mass of solution. Add: g solute + g solvent Example 4: A student wants to make a 5.0% solution of rubidium chloride and water with 10.0 g rubidium chloride. How much water is needed? If given the %, work backwards to find the unknown mass.

11. Exit Slip Show all your work and label your answer with the correct units. 1.A chemist dissolves 20 g silver nitrate in 180 g water. What is the percent concentration? 2.A glass of koolaid contains 4.0 g sucrose and 96 g water. What is the percent concentration? 3.A fish tank contains 4 mol NaCl (salt) and 1000 g water. What is the percent concentration?