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Unit: Chemical Interactions Chapter 8: Solutions When substances dissolve to form solutions, the properties of the mixture change. 8.1: A solution is a.

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Presentation on theme: "Unit: Chemical Interactions Chapter 8: Solutions When substances dissolve to form solutions, the properties of the mixture change. 8.1: A solution is a."— Presentation transcript:

1 Unit: Chemical Interactions Chapter 8: Solutions When substances dissolve to form solutions, the properties of the mixture change. 8.1: A solution is a type of mixture 8.2: The amount of solute that dissolves can vary 8.3: Solutions can be acidic, basic, or neutral 8.4: Metal alloys are solid mixtures

2 Review / warm-up  What are their chemical formulas? What are the elements?  Which is an ionic compound and which is a covalent compound?  Are the properties of each compound the same/different than the atoms/elements that form them?  What is the different in how these compounds are held together? 8.1: A solution is a type of mixture Na Cl O C O animation

3 8.1 A solution is a type of mixture 8.1: A solution is a type of mixture

4 The parts of a solution are mixed evenly  Mixture: a combination of substances – ex: fruit salad, chili  Can physically separate ingredients because they are not chemically changed – still the same substances  If a mixture is so completely blended together…  The ingredients canNOT be separated and identified as different substances  Solution: a type of mixture, called a homogeneous mixture  “same throughout” (“well-mixed”)  All portions of the the mixture have the same properties  Sand + Water  Sand sinks to the bottom ; Solution?  Sugar + water  sugar is dispersed throughout; Solution?  Other common solutions: seawater, gasoline, liquid part of blood 8.1: A solution is a type of mixture

5 Solutes and Solvents – components of a solution  Solutions – have a definite composition  Solute – a substance that is dissolved to make a solution  When it dissolves, it separates into individual particles  It is dissolved into the…  Solvent – a substances that dissolves a solute  Most common: water  Others – ex: turpentine, soaps - to remove oils  After the solute dissolves and separates into individual particles, it is not possible to identify the solute and solvent as different substances  Ex: 8.1: A solution is a type of mixture SolutionSolutesolvent Salt water blood saltwater Calcium ions, sugar water

6 8.1: A solution is a type of mixture Solvent (water) animation Solute (salt) A salt water solution

7 Types of Solutions  Gas Solution:  Ex: air = oxygen (an other gases) dissolved in nitrogen  Liquid Solution:  Ex: vinegar = acetic acid dissolved in water  Solid Solution:  Ex: bronze = tin dissolved in copper  Must first be melted to a liquid, then mixed, then cooled to solid  Mixed?  Ex: soda = carbon dioxide dissolved in water solution  Ex: saltwater = salt dissolving in water 8.1: A solution is a type of mixture

8 Solution Worksheet solute solvent solute solvent

9 Suspensions  Suspension: the particles added are larger than those found in a solution, so instead of dissolving, these larger particles turn the liquid cloudy  Ex: Flour added to water  Can sometimes separate the components of the suspension using a filter 8.1: A solution is a type of mixture

10 Solvent and solute particles interact  The parts of a solution are not changed into new substances  The solute and the solvent can still be physically separated, though they do interact  Ex: a solid dissolves in a liquid, the particles of the solute are surrounded by particles of the liquid (solvent)  The solute particles become evenly distributed through the solvent 8.1: A solution is a type of mixture

11 Solvent and solute particles interact (2)  The way a solid compound dissolves in a liquid depends on the type of bonds in the compound  Ionic compounds split apart into individual ions  Ex: table salt dissolves in water – the sodium and chloride ions separate, and each ion is surrounded by water molecules  Covalent compounds dissolved in water, the molecules stay together and are surrounded by solvent molecules  Ex: table sugar dissolves in water – C12H22O11 stays as such 8.1: A solution is a type of mixture

12 Properties of solvents change in solutions  Solutes change the physical properties of a solvent in every solution  A solution’s physical properties differ from the physical properties of the pure solvent  Dependent on the amount of solute added

13 Lowering the Freezing Point  Freezing Point: temperature Liquid  Solid  A solvent’s freezing point is lowered when a solute is dissolved in it  Ex: add salt to water – freezing point drops below 32 o F ( 0 o C)  Useful for snow and ice on sidewalks and roads (water freezes at a lower temperature, can help to melt ice) A limit: can get down to -6 o F ( -21 o C) before the melted ice will freeze again Ice cream maker: Canister surrounding ingredients holds a mixture of salt and ice The lower freezing point causes the ice to melt, absorbing heat from surroundings This includes the ice cream ingredients, which get chilled Then tiny ice crystals form all at once in the ice cream mixture rather than a few crystals growing larger over time (as would happen in a regular freezer)

14 Raising the Boiling Point  Boiling Point: temperature liquid  gas  Boiling point of a solution is higher than the boiling point of the pure solvent  Solution can remain a liquid at a higher temperature than its pure solvent  Ex: boiling point of water = 212 o F (100 o C)  Salt raises the boiling point of water  Dependent on amount of salt added  Summary: a solute lowers the freezing point and raises the boiling point of the solvent in the solution  Extends the temperature range in which the solvent remains a liquid  Uses: antifreeze in a car’s radiator (ethylene glycol added to water)  Prevents the water from freezing in the winter  Keeps it from boiling in the summer

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