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Solutions. What is a solution? A solution is a mixture that has the same composition, color, density and even taste throughout The most common solutions.

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Presentation on theme: "Solutions. What is a solution? A solution is a mixture that has the same composition, color, density and even taste throughout The most common solutions."— Presentation transcript:

1 Solutions

2 What is a solution? A solution is a mixture that has the same composition, color, density and even taste throughout The most common solutions are liquids and have water in them, but not all are To describe a solution, you might say that one substance is dissolved in another

3 Parts of a solution The substance being dissolved is the solute, and it is always in lower amounts that the solvent The solvent is the substance that does the dissolving and is always in higher amounts than the solute Water is known as the “Universal Solvent” because it can dissolve many things

4 Non liquid Solutions Solutions can be solid, like bronze, which is a mixture of both copper and tin. Brass is a mixture of copper and zinc. Solid solutions are known as alloys Air is a gaseous solution that is a mixture of Nitrogen, oxygen, carbon dioxide, hydrogen and others.

5 Identify the solvent and solute in each Kool Aid Ocean water Bronze Air Carbonated soft drink

6 Water is Polar Water is a special molecule that can dissolve just about everything The trick is, like dissolves like Water is a polar liquid, so it can dissolve polar solids such as salt Something is considered polar if it has a positive area and a negative area in the same molecule

7 Polar Molecules Water Table Salt and Water

8 How does sugar dissolve in water Step 1: Water clusters around sugar molecules, negative ends attracted to positive Step 2: Water molecules pull sugar molecules into solution Step 3: Water and sugar molecules mix evenly, forming a solution

9 More Dissolving Gases can dissolve in liquids Liquids can also dissolve in liquids Making solid solutions, or alloys is more complicated, you must melt the solids down and mix them so they will remain mixed when cooled

10 Rate of Dissolving When one thing dissolves in another, it does so at a constant rate You can increase the dissolving rate by doing three things 1. Stirring- brings more solvent into contact with solute 2. Decreasing crystal size (grinding)- gives solvent more surface area to dissolve 3. Increase temperature- makes particles move faster and mix easily

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12 Solubility and Concentration How much can dissolve? Solubility is the maximum amount of solute that can be dissolved in a solvent at a certain temperature Concentration depends on how much solute is dissolved in the solvent A solution with more solute than another in the solvent is considered more “concentrated” Example orange drink is 10 % juice, where orange juice is 100 % juice– the juice is more concentrated in one than the other

13 Saturated vs Unsaturated Solutions A saturated solution is one that holds all the solute that it can at a certain temperature. In an unsaturated solution, more solute can be dissolved in the solvent at a certain temperature

14 Solubility Curves You can use these to determine how much of a solute can dissolve in a given solvent at a certain temperature

15 Supersaturated Solutions Unstable solution that have more solute dissolved in the solvent than they should You can supersaturate a solution by heating it, forcing more solute to dissolve, then letting it cool As it cools, some of the solute falls out of solution You can make rock candy using a supersaturated solution of sugar and water

16 Solubility of Gases You can increase the amount of a gas dissolving in a liquid by INCREASING the pressure or DECREASING the temperature More carbon dioxide gas is dissolved in a cold soft drink than a warm one, that’s why sodas get “flat” as they warm up

17 Particles in Solution Pure water is a poor conductor of electricity. In order for water to conduct electricity well, you have to add ions to it. Solutions of ions that conduct electricity well are called electrolytes

18 Effects of Solute Particles Adding antifreeze to the water in your car radiator both lower the freezing point of the water AND raise the boiling point of water Meaning, that with the antifreeze, the water in your radiator won’t freeze or boil as easily Some animals such as polar fish and caribou have a natural antifreeze in their bodies that keep them from freezing in cold temperatures

19 When Water Won’t Work Water cannot dissolve all substances. If a substance is non-polar, meaning it has even charges all the way through and no negative and positive ends, the water cannot dissolve it Some substances are both polar and non-polar because part of the molecule is charged, and the other part is not. Ethanol is an example.

20 Nonpolar Solvents Goo gone, lighter fluid, dry cleaning solution are all examples of nonpolar solvents and can dissolve things that water can’t. Nonpolar solvents are often toxic and flammable They can produce harmful vapor

21 The Chemistry of Soap Non polar ends of soap attach to dirt and oil and dissolve it Polar ends of soap mix with water and all is washed away Soap works because it is BOTH Polar and Non-polar

22 Chapter 23

23 Acids Acids can be harmful or they can be safe, depending on the specific one What they all have in common, is that in solution, they all release H+, hydrogen, or hydronium ions into water Acids have a sour taste Some are corrosive and can react strongly with certain metals Acids also react with indicators (a substance used to identify acids and bases) Litmus paper, for example, changes red in presence of an acid

24 Common Acids Hydrochloric Acid HCl – gastric juices (stomach acid) Ascorbic Acid – vitamin C Citric Acid– found in citrus fruits Carbonic Acid- carbonated drinks Sulfuric Acid– battery acid

25 Bases In solutions, bases release OH- or hydroxide ions into water Bases are the opposite of acids They are smooth and slippery They have a bitter taste Strong bases are corrosive and can burn Litmus paper turns blue in bases

26 Common Bases Soaps Cleaning supplies Bleach Milk of Magnesia Alka Seltzer and Tums (antacids)

27 Ammonia is Special Ammonia is a strong base used as a cleaner It does not form hydroxide ions in solution Do not use ammonia with anything containing chlorine like bleach If you mix the two together, it makes a poisonous gas that is fatal

28 Dissociation When acids and bases dissolve in water, the ions are attracted to the water and in some cases, they are mixed completely in the water This is called dissociation When acids dissociate, they release H+ ions in water (hydronium) When bases dissociate, they release OH- ions in water (hydroxide)

29 Strong and Weak Acids and Bases The strength of an acid or base depends on the number of ions dissociated in solution A strong acid or base has many ions in solution, dissociates completely A weak acid or base has few ions in solution, does not dissociate completely Ions meaning H+ for acids and OH- for bases

30 pH of Solutions pH of a solution is the measure of the concentration of H+ ions in solution The pH scale ranges from 0 to 14 An acid has a pH below 7 A base has a pH above 7 7 is neutral, pure water is an example You can measure pH using a pH meter or indicator pH paper, which turns a certain color for each pH value

31 pH Scale

32 Blood pH In order for blood to function properly, it must have a pH between 7 and 7.8 Many enzymes cannot work outside this range How is it that you can eat acidic foods and not change your blood pH? Your blood contains buffers, solutions containing ions that react with acids and bases to minimize changes in pH

33 Neutralization Antacids such as Tums or Alka Seltzer produce what is called neutralization in your stomach This is because too much acid can cause discomfort Neutralization is a chemical reaction between an acid and a base which produces water Remaining ions in a solution react to form salts

34 Salts Salts are essential for healthy life Most salts contain a positive metal ion and an ion with a negative charge Ammonium salts contain the ammonium ion instead of a metal


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