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Classic Chem The base-ics about bases 9-12 Science Std: Chem 5a
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We started with: Solutions Equations 2H 2 + O 2 2H 2 O Definition of Acid and Base and pH And properties of acids
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One last area to cover… What is a base Remember that: A base is: A compound that increases the concentration of hydroxide ions in a water solution OH -
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And that : You know it’s a base By using a pH meter This is one way to know the actual pH value
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Now its time to look at : How you can tell it is a base There are 5 ways to tell something is a base Sound familiar? – it will…
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What is a base? The first property: Bases mixed in water have a bitter taste But like acids – don’t taste everything to test Unsweetened “Bakers” chocolate has a bitter taste
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Why not? Just like acids Bases can burn your mouth Just as fast as an acid can If the pH is high enough… 7 14
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Why not? But there are some bases you can taste… Brussel sprouts So a Bitter taste is a sign that it is a base Spinach
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Remember the difference Acids are sour Bases are bitter Lemons Soda Water
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What is a base? The second property: Bases change the color of acid/base indicators Blue to Red - AcidRed to Blue - Base
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What is a base? The second property: And yes, cabbage can be used as a pH indicator for bases too As for plants – they like slightly acidic soil (pH 7-5)
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What is a base? The third property: A watered down basic solution feels slippery What is something that feels slippery?
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What is a base? The third property: Soaps Soaps have a slippery feel because they make a dilute basic solution
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What is a base? The fourth property: Bases react with acids to make salts and water Just like we covered with acids The cation (+) comes from the base
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What is a base? The fourth property: An example: Sodium Hydroxide (Base) Hydrochloric Acid Na OH H Cl
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The fourth property: When you mix these in water… The sodium and hydroxide split and make ions And the hydrogen and chlorine split and make ions Na OH H Cl What is a base?
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The fourth property: Once the ions split The sodium and chlorine get together And the hydrogen and hydroxide get together Na OH H Cl What is a base?
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The fourth property: And what do you get? Sodium Chloride (Salt) And H 2 O (Water) Na OH H Cl What is a base?
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The fifth property: Some bases conduct electricity Just like some acids What is a base?
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The fifth property: If the base has an ionic bond The ions in the base Will conduct electricity just like acids Na OH + - What is a base?
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And that’s the list Review the 5 properties of bases 1. Bases in water have a Bitter Taste
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And that’s the list Review the 5 properties of bases 2. Change the color of pH indicators
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And that’s the list Review the 5 properties of bases 3. Dilute solutions are Slippery
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And that’s the list Review the 5 properties of bases 4. React with acids to make water and salts
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And that’s the list Review the 5 properties of bases 5. Some bases conduct electricity
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So what are the differences… What is the same for acids and bases Acids Bases Properties Change color of Indicators Make Salt and Water Some Conduct Electricity
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So what are the differences… Acids Bases Properties Taste Sour Bitter Other properties React with metals to make gases Dilute solutions are slippery What is different for acids and bases
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Your Homework….. Review properties of acids and bases to prepare for lab
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