Why do vinegar or lemon juice taste sour? They are Acids! The term acid comes from the Latin term...

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ACIDS AND BASES

Transcript of Why do vinegar or lemon juice taste sour? They are Acids! The term acid comes from the Latin term...

Page 1: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

ACIDS AND BASES

Page 2: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

ACIDS & BASES Why do vinegar or lemon juice taste

sour? They are Acids! The term acid comes from the Latin

term acere, which means “sour” In the 17th century, chemist Robert

Boyle first labeled substances as acids or bases according to certain characteristics.

1st reasonable definition for acids and bases was not proposed until the 19th century, with Swedish scientist Svante Arrhenius

Page 3: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

ARRHENIUS Stated that Acids contained Hydrogen and

release hydrogens into solution

Bases release OH- (Hydroxide Ions) into solution.

Acids and Bases can combine to neutralize, or counteract each other.

Page 4: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

ACIDS Acids in the home

Dilute weak acidsHave a sour tasteSafe to use in food, but can still hurt if they get into a cut or eyes

ExamplesVinegar = Ethanoic AcidFizzy Drinks (Soda) = Carbonic AcidTea = Tannic AcidVitamin C = Ascorbic AcidLemons = Citric Acid

Page 5: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

BASES React with oils and fats Often used in strong household

cleaners Examples

Drain cleaners and oven cleaners contain Sodium Hydroxide

Ammonia is also used in cleanersWise to wear gloves with these substances

because it will burn skin! Weak bases are found in toothpaste,

antacid tablets (help to cure an upset stomach) and baking powder

Page 6: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

INDICATORS AND THE PH SCALE Indicator: substance that can change color when they are added to acidic or alkaline/basic solutions

You can prepare your own homemade indicators

Two commonly used indicatorsLitmus paperUniversal indicator

Page 7: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

LITMUS PAPERRed Litmus Blue Litmus

Acidic Solution Stays Red Turns Red

Neutral Solution Stays Red Stays Blue

Alkaline/Basic Solution

Turns Blue Stays Blue

Page 8: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

UNIVERSAL INDICATOR Is a mixture of several different indicators It shows us EXACTLY how strongly acidic

or alkaline/basic a solution is Measured using the PH Scale, which

runs from 0 to 14 Has many different colors, from red for strong

acids to dark purple for strong bases. In the middle, neutral pH 7 is indicated by green.

Page 9: Why do vinegar or lemon juice taste sour?  They are Acids!  The term acid comes from the Latin term acere, which means “sour”  In the 17 th century,

PH SCALE Neutral solutions have a pH of 7 Acidic solutions have a pH less than 7 Basic solutions have pH values more than 7 The closer to pH 0 you go, the more

strongly acidic The closer to pH 14 you go, the more

strongly alkaline/basic