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Published byPatience Warner Modified over 8 years ago
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Classic Chem It’s the acid test 9-12 Science Std: Chem 5a
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We started with: Solutions A solution is: A homogeneous mixture Of 2 or more substances In a single phase
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We then looked at : Chemical Equations NaCl + AgNO 3 The reactants An equation shows: AgCl + Na + + NO 3 - And the products It can show how much is there and if there are ions or whole compounds
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And yesterday we covered What is an acid and a base An acid is: A compound that increases the concentration of hydrogen ions in a water solution A base is: A compound that increases the concentration of hydroxide ions in a water solution H+H+ OH -
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And yesterday we covered And the pH scale The scale goes from 1 - 14 Between 1 and 7 is acidic And the center of the scale is a 7 1 147 And between 7 and 14 is basic And a pH of 7 is neutral
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Now its time to look at : How you can tell it is an acid You can use a pH meter To read the pH and tell if it is an acid or a base But there are other ways to tell….
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Now its time to look at : How you can tell it is an acid There are 5 ways to tell something is an acid So let’s look at them
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What is an acid? The first property: Acids mixed in water have a sour taste But you shouldn’t taste everything to see if it is an acid Let’s see why
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Why not? First of all….. If the acid is concentrated If the pH is really low The acid can eat up your mouth 1 7
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Why not? Next…. A lot of acids Are poisons So they can kill you if you eat enough
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Why not? But there are some acids you can taste… Citric Acid This gives some fruit their tangy taste So a sour taste is a sign that it is an acid
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What is an acid? The second property: Acids change the color of acid/base indicators You may have used litmus paper before to test things And see if something is an acid
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What is an acid? The second property: We will use one of these other things to make our own pH indicator But more on this when we do the lab….
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What is an acid? The second property: But there are other things that can change color Hydrangeas can change color with soil acidity And there are lots of other things that work too
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What is an acid? The third property: Some acids react with metals to release a gas Depending on the type of acid And the type of metal You can make different gasses
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What is an acid? The third property: Here are some different types: Sulfuric Acid makes hydrogen gas (flammable) Nitric acid makes nitrous oxide gas (poison) Movie
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What is an acid? The third property: Smog mixes with water vapor and makes sulfuric acid This mixes with rain water And becomes acid rain Which can dissolve metal and stone
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What is an acid? The fourth property: Acids react with bases to make salts and water These salts are different than you think So let’s make this clear
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What is an acid? The fourth property: A salt is any ionic compound That comes from neutralizing an acid with a base Example: HCl and NaOH Make NaCl
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What is an acid? The fourth property: A salt is any ionic compound That comes from neutralizing an acid with a base Example: H 2 SO 4 and CuO Make CuSO 4
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What is an acid? The fourth property: Other salts include Sodium carbonate Zinc sulfide Ammonium Nitrate Used to make soap To make glass and lenses To make fertilizer
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What is an acid? The fourth property: We talked about making water…. An acid adds hydrogen Ions A base adds hydroxide ions Add them together…. H+H+ And you get water OH - H2OH2O
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What is an acid? The fifth property: Some acids conduct electricity This means you can put 2 wires in an acid solution And pass an electrical current through it
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What is an acid? The fifth property: How does this work? When you put some acids in water Like HCl acid They break apart into ions in solution HCl
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What is an acid? The fifth property: The ions have electric charge And these charges are floating around The anions have a spare electron attached ready to move HCl + -
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What is an acid? The fifth property: The electrons in a current Pass from ion to ion in the solution So the solution is like a wire HCl + -
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And that’s the list Review the 5 Acid Tests 1.Acids in water have a sour taste 2. Change the color of pH indicators 3. React with metals to release gas 4. React with bases to make water and salts 5. Some acids conduct electricity
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Your Homework….. Quiz Retake is due today Otherwise No homework just yet.
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