Unit 5: (2) Acids and Bases Physical Science

Properties of Acids Produce H+ (as H3O+) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule) Taste sour Corrode metals Electrolytes React with bases to form a salt and water Acid Base

Properties of Acids pH is less than 7 Acid indicators: Red litmus paper stays red. Blue litmus paper turns red. Phenolphthalein stays colorless. Alkali = Base

Properties of Acids React w/ metals to form H2(g) + a metal compound. Zinc Hydrochloric acid Hydrogen bubbles React w/ metals to form H2(g) + a metal compound. Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g)

Some Common Acids Acetic acid C2H4O2 Vinegar Hydrochloric acid HCl Gastric juice, cleaners Carbonic acid H2CO3 Club soda Nitric acid HNO3 Removing warts Phosphoric acid H3PO4 Found in soft drinks Lactic acid C3H6O3 Builds up in muscles during workouts

Recognizing Acids All acids contain H. Acid formulas begin w/ H. Not all substances with H in them are acids. HCl = acid CH4 = not an acid When dissolved in H2O, acids form H+ ions. H+ ion = proton Acids are proton donors. H+ ions combine w/ H2O to form H3O+1 H3O+1 = hydronium ion

https://www.youtube.com/watch?v=cbN37yRV- ZY

Hydronium Ion Production HCl H2O Hydronium Ion Production Cl-1 H3O+1

Properties of Bases Produce OH- ions in water Taste bitter, chalky Are electrolytes Feel soapy, slippery React with acids to form salts and water

Properties of Bases pH greater than 7 Can be as poisonous and corrosive as acids. Base indicators: Red litmus turns blue. Blue litmus stays blue. Phenolphthalein turns pink. Alkali = Base

Some Common Bases NaOH sodium hydroxide lye KOH potassium hydroxide liquid soap Ba(OH)2 barium hydroxide stabilizer for plastics Mg(OH)2 magnesium hydroxide “MOM” Milk of magnesia Al(OH)3 aluminum hydroxide Maalox (antacid)

Recognizing Bases Most bases contain the hydroxide ion, OH-1. Examples: NaOH (sodium hydroxide) KOH (potassium hydroxide) Ca(OH)2 (calcium hydroxide) Sr(OH)2 (strontium hydroxide) Some bases do not contain OH-1 ions: NH3 (ammonia) PO4-3 (phosphate ion) Form OH-1 ion when diss. in H2O. OH-1 = hydroxide ion OH-1 + H+1  H2O Bases are proton acceptors.

https://www.youtube.com/watch?v=GrPQv6QE I8Y

Acid / Base Reactions When Acids and Bases are combined a Neutralization reaction produces water and a salt - very important equation! 1. Hydrochloric Acid and Sodium Hydroxide yields water and Sodium Chloride a. HCl + NaOH  H2O + NaCl B. H+ + Cl- + Na+ + OH-  H2O + NaCl 2. Salt is an ionic compound formed from an acid / base reaction (neutralization)

Acid-Base Neutralization Rxn between acid and base. Double replacement rxn. Products are always a salt and H2O. Salt = ionic compound (metal + nonmetal) Examples: HCl (acid) + NaOH (base)  NaCl (salt) + H2O 2HNO3 (acid) + Ba(OH)2 (base)  Ba(NO3)2 (salt) + 2H2O 3H2SO4 (acid) + 2Al(OH)3 (base)  Al2(SO4)3 (salt) + 6H2O

https://www.youtube.com/watch?v=TS- I9KrUjB0

Check for Understanding Acid formulas usually begin with which element? Answer: H Base formulas usually end with which polyatomic ion? Answer: OH-1 Acid-base neutralization reactions produce a salt and _____. Answer: H2O

pH Scale pH a measure of the concentration of H3O+ ions in solution measured with a pH meter or an indicator with a wide color range 7 INCREASING ACIDITY NEUTRAL BASICITY 14

The pH Scale

pH Values of Common Solutions Battery acid, pH = 1 Lemon juice, pH = 2 Apples, pH = 3 Tomatoes, pH = 4.5 Milk, pH = 6.6 Pure water, pH = 7 Human blood, pH = 7.4 Ammonia, pH = 11 Lime solution, pH = 12 – 13 Lye solution, pH = 13

Electrolytes Electrolyte Substance that conducts an electric current when dissolved. Produces ions in sol’n. Salts, acids, and bases. NaCl (salt)  Na+1(aq) + Cl-1(aq) HCl (strong acid) + H2O  H3O+1(aq) + Cl-1(aq) NaOH (strong base)  Na+1(aq) + OH-1(aq)

https://www.youtube.com/watch?v=DupXDD87 oHc

https://www.youtube.com/watch?v=OMXMlWy bv8A