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Chapter 9 Families of Chemical Compounds – Acids & Bases.

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Presentation on theme: "Chapter 9 Families of Chemical Compounds – Acids & Bases."— Presentation transcript:

1 Chapter 9 Families of Chemical Compounds – Acids & Bases

2 Flashback – What’s a Chemical Compound?  As we have learned, when elements bond together due to ionic or covalent bonding, they form chemical compounds.  Different combinations of elements form different compounds.  2 of these types of compounds are acids and bases.

3 Properties of Acids  Sour tasting  Affect indicator colors  blue litmus paper turns red  phenolphthalein remains colorless  Acids react with active metals to form Hydrogen gas plus a metal compound

4 Properties of Acids  When acids are dissolved in water, they produce positive hydrogen ions (H + ) (this is a proton)  Acids are often known as proton donors  strong acids dissolved in water produce a lot of hydrogen ions and are good electrolytes – this means that they will conduct electricity very well ex – sulfuric acid, hydrochloric acid  weak acids dissolved in water do not produce a lot of hydrogen ions and are not good electrolytes ex - acetic acid (vinegar)

5  Bitter taste  Slippery – ex soap  Affect indicator colors  red litmus paper turns blue  phenolphthalein turns bright pink  Emulsify (dissolve) fats and oils  This is why we use bases as soap, they dissolve dirt and oils that are on our body)  This is why cleaners often contain ammonia, the cleaner will “cut” through grease and we can wipe it away. Properties of Bases

6  Usually contain OH- ion  Why are bases called proton acceptors?  their OH- ions combine with H+ ions (protons from acids) to form water  Common bases  sodium hydroxide (NaOH)  potassium hydroxide (KOH)  Ammonia  Lye  Soap  Milk of magnesia Properties of Bases

7 Common Household Acids and Bases

8 The pH Scale The pH Scale   The name, pH, has been reported to come from a variety of places including: pondus hydrogenii (Latin), pouvoir hydrogène (French) and potential of hydrogen (English).   However pH is actually a shorthand for its mathematical definition, in chemistry a small p is used in place of writing − log10 and the H should more correctly be [H+], standing for concentration of hydrogen ions  Simply put - the pH of a solution is a measure of the amount of its H + ion.  Remember that the H + ion is what is formed when an acid is dissolved into water.

9 The pH Scale The pH Scale  SO, the pH of a solution is actually a measure of how acidic it is.  But, the scale is a reverse scale, so the lower the number, the higher the acidity.

10  the range is from 0 to 14  What is a solution like if...  its pH is below 7?  its pH is 7?  its pH is above 7? The pH Scale acidic neutral basic

11 When Acids & Bases Combine…  Formation of Salts  When acids react chemically with bases, they neutralize each other AND form a type of compound called salts.  water – the compound formed from the positive H ion of an acid and the negative OH ion of a base  salt – the compound formed from the negative ion of an acid and the positive ion of a base.  neutralization - acid and base react to form a salt & water. It is a type of double replacement reaction. Oxi #’s +1 -1 +1 -1 +1 -1 HCl + NaOH  NaCl + H 2 O HCl + NaOH  NaCl + H 2 O “Hydrochloric Acid plus Sodium Hydroxide yields Sodium Chloride and Water”

12 When Acids & Bases Combine…  How to Calculate a Neutralization Reaction  the acid’s H’s and the base’s OH’s must be the same #  use coefficients if you need to  These will combine to form the water (H 2 O)  put together the leftover parts to make the salt (base part 1st)  don’t multiply subscripts, instead wrap the part in parentheses and put the needed subscript outside  Ex #1: HCl + KOH  1 H and 1 OH cancel  this leaves a Cl and a K  thus, the salt produced is KCl

13  Ex #2: H 2 SO 4 + NaOH  2 H’s but only 1 OH, so you have to put a 2 in front of the the NaOH so that you have enough OH’s to “hook up” with the H’s to make water (H 2 O)  this leaves SO 4 and 2 Na  thus, the salt produced is Na 2 SO 4  (base part first, acid part second)  What salt is made from each of the following neutralizations?  HNO 3 and NaOH  LiOH and HBr  H 2 SO 4 and KOH  HCl and Al(OH) 3

14 Neutralize these or I’ll whine.  Complete the following neutralization reactions.  Circle the acid, Square the base, & Triangle the salt.  LiOH + HBr -->  HCl + FrOH -->  H 2 SO 4 + KOH -->  Ca(OH) 2 + HF -->  H 2 SO 4 + Al(OH) 3 -->

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