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Solutions Day 2

Solutions Day 2. Chemistry Ms. Boon 11.28.12. Objective. Catalyst. I can express the concentration of a solution by percent concentration. Agenda. Catalyst Homework review Percent concentration Exit slip. HW: Read pp. 460-464, 468-470 Problems pp. 488 #4, 16, 21, 25.

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Solutions Day 2

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  1. Solutions Day 2 Chemistry Ms. Boon 11.28.12

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

  3. Homework Review: pp. 459 The solvent is the substance in excess. There is more of it. The solute is the substance dissolved in the solvent. (a) solvent: water; solute: carbon dioxide (b) solvent: water; solute: apple extract (c) solvent: water; solute: coffee filtrate (d) solvent: water; solute: salt 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 (K2SO4)?

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

  10. Finding the Percent Concentration % concentration = g solute___ x 100% g solution The denominator is the mass of solution. Add: g solute + g solvent If given the %, work backwards to find the unknown mass. 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?

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

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