Why do vinegar or lemon juice taste sour? They are Acids! The term acid comes from the Latin term...
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Transcript of Why do vinegar or lemon juice taste sour? They are Acids! The term acid comes from the Latin term...
ACIDS AND BASES
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
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.
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
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
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
LITMUS PAPERRed Litmus Blue Litmus
Acidic Solution Stays Red Turns Red
Neutral Solution Stays Red Stays Blue
Alkaline/Basic Solution
Turns Blue Stays Blue
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.
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