Acids and Bases Notes

Acids and Bases Notes

1. The pH scale (power of Hydrogen or potential Hydrogen) is used to determine the acidity or base of a solution. The pH scale ranges from 0-14--- acids 0-6.9, neutral is 7, bases 7.1-14.

2. Indicators are substances that change color at different pH levels.

· Litmus paper—white paper that has been soaked in a dye solution which will change color in an acid or a base

Ø Red litmus paper---red paper turns blue when exposed to bases

Ø Blue litmus paper---turns red or pink when exposed to acids

· Alkacid paper (universal indicator paper)---checks for both acids and bases; indicates the approximate pH solution

· Red cabbage juice

· Phenolphthalein--- it is colorless below pH 8.5, but turns red or pink above pH 9.0

· Electronic pH indicator device---tends to be more accurate

Acids (0-6.9)	Bases (7.1-14)
sour taste	bitter taste
often corrosive	often corrosive
conducts electricity (electrolyte)	conducts electricity (electrolyte)
used in pickling (removes impurities from metals)	feels slippery and slimy
neutralizes bases	neutralizes acids
turns blue litmus paper red or pink	turns red litmus paper blue
reacts with some metals to produce hydrogen gas; A solution that produces an excess of H⁺ ions. It comes from the Latin word acidus that means "sharp" or "sour". Most acids have chemical formulas whose first element is H (hydrochloric acid found in stomach---HCl; sulfuric acid found in car batteries H₂SO₄ Acids form hydronium ions (H₃O⁺) when dissolved in water.	produces hydroxide ions when bases and water mix together as a solution; a solution that has an excess of OH^- ions; another word for base is alkali Many bases have chemical formulas that end in OH. NaOH is sodium hydroxide which is a base used in drain cleaner. Ca(OH)₂ is calcium hydroxide which is a base used in fertilizer.
Examples of acids:	Examples of bases:
citrus fruits (lemons, oranges) pineapples, soda, yogurt, sour milk, grapes, stomach acid or gastric juice (HCl), vinegar (acetic acid), shampoo, tomatoes, bananas, decaying animals, volcanic ash, car batteries (sulfuric acid)	soaps, ammonia, sink drain cleaners, blood, ocean water, eggs, baking soda (sodium bicarbonate--- NaHCO₃)

3. Neutralization reaction---

· The chemical reaction between an acid and a base that results in both substances losing their distinctive properties.

· a salt and water are created

· a salt is an ionic compound that forms when a metal ion replaces the hydrogen ion of an acid

· when acids and bases are combined, they neutralize each other

REACTIONS WITH ACIDS

ACID	+	BASE	SALT	+	WATER
Hydrochloric Acid	+	Sodium Hydroxide	Sodium Chloride	+	Water
HCl	+	NaOH	NaCl	+	H₂O

ACID	+	METAL	SALT	+	HYDROGEN GAS
Hydrochloric Acid	+	Magnesium	Magnesium Chloride	+	Hydrogen
HCl	+	Mg	MgCl₂	+	H₂

ACID	+	CARBONATE	SALT	+	WATER	+	CARBON DIOXIDE GAS
Hydrochloric Acid	+	Calcium Carbonate	Calcium Chloride	+	Water	+	Carbon Dioxide
HCl	+	CaCO₃	CaCl₂	+	H₂O	+	CO₂

Source credit----http://qldscienceteachers.tripod.com/junior/chem/acid.html

Using the Periodic Table to Predict Acids and Bases---

a. Acids form when hydrogen chemically combines with certain nonmetals.

b. A hydrogen atom that gives up its 1 valence electron to another element becomes a hydrogen ion (H+).

c. A hydrogen atom will readily form an ion to bond with an atom that has seven valence electrons (halogen family).

d. Acids --- Very reactive elements tend to form stronger bonds.

e. In general, the weaker the bond between hydrogen and another element in an acid, the stronger the acid will be.

f. A base forms when a hydroxide ion (OH-) joins with a metal.

g. The metals in group 1 (alkali metals) and group 2 (alkaline earth metals) readily form bases with the hydroxide ion.