Families of Chemical Compounds – Acids & Bases Chapter 9 Families of Chemical Compounds – Acids & Bases

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.

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

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)

Properties of Bases 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 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

Common Household Acids and Bases

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.

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.

The pH Scale 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? acidic neutral basic

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 + H2O “Hydrochloric Acid plus Sodium Hydroxide yields Sodium Chloride and Water”

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 (H2O) 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

What salt is made from each of the following neutralizations? Ex #2: H2SO4 + 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 (H2O) this leaves SO4 and 2 Na thus, the salt produced is Na2SO4 (base part first, acid part second) What salt is made from each of the following neutralizations? HNO3 and NaOH LiOH and HBr H2SO4 and KOH HCl and Al(OH)3

Neutralize these or I’ll whine. Complete the following neutralization reactions. Circle the acid, Square the base, & Triangle the salt. LiOH + HBr --> HCl + FrOH --> H2SO4 + KOH --> Ca(OH)2 + HF --> H2SO4 + Al(OH)3 -->