WRITE YOUR OWN NOTES ON THIS POWERPOINT AND ALL EXAMPLES. Acids and Bases- 2015

Acid Base Taste-----sour Touch stings Reacts vigourously with metals Conducts Blue litmus turns red Taste-- bitter Touch- slippery Little reaction with metals Conducts Red litmus turns blue

There are 3 definitions of acids and bases. Each definition allows more substances to be classified as an acid or base

Arrhenius Definition Arrhenius Acid- substance that ionizes to produce H + ions ex- HCl Arrhenius Base- substance that dissociates to produce OH - ionsex- NaOH Problem- must be in a water solution

Lewis Definition Uses electrons and usually deals with organic chemistry

Bronsted-Lowery Definition Acid- any substance that donates H + Base- any substance that accepts H + This definition allowed Ammonia (NH 3 ) to be classified as a base Water solution is NOT necessary

Examples

Common Acids and uses HCl- hydrochloric acid- stomach acid and concrete cleaner H 2 SO 4 - sulfuric acid- dehydrating agent, fertilizers HNO 3 - Nitric acid- explosives H 3 PO 4 - Phosphoric Acid- soft drinks CH 3 COOH- Acetic Acid- vinegar

Common Bases NH 3 Ammonia- cleaner NaOH- sodium hydroxide-lye soap, drain cleaner Mg(OH) 2 - Magnesium hydroxide- antacid- MOM Calcium carbonate- antacid

Bases usually contain OH - (hydroxide) but carbonates and phosphates can form basic salts  NaOH, Ca(OH) 2  Salts: CaCO 3 Na 3 PO 4  Calcium carbonate is found in chalk, TUMS, sea shells

Organic bases contain the amine functional group  (-NH 2 )

The term alkaline refers to a base solution  Example- shampoo commercial advertises that the shampoo is a slightly alkaline (slightly basic)

Relationship between Acids and Bases Conjugate Acid –Base pairs: molecules and ions that differ only by one proton (or H +1 ) HCN + H 2 O H 3 O +1 + CN -1

Acids ionize to form a H + ion Monoprotic- 1 ionizable H +  Examples: HCl, HF, HBr,

Diprotic Acid- contains 2 hydrogen  H 2 SO 4  Diprotic Acids ionize on H +1 at a time.

Triprotic Acid- contains 3 hydrogens  H 3 PO 4 Phosphoric Triprotic Acids ionize on H +1 at a time.

A Binary Acid is an acid that contains hydrogen and one other element  HBr  HCl  HF  Hydro ______ic

Oxyacid- an acid that contains oxygen H 2 SO 4 HNO 3 H 3 PO 4

Carboxylic Acid- An organic acid that will always contain the functional group -COOH  Example- Acetic Acid CH 3 COOH

Strong Acid ionizes completely to produce strong electrolytes  HCl  H + + Cl -  HI and HBr are also strong acids (will discuss diprotic acids later)

Weak Acids ionize incompletely to form weak electrolytes  HF H + + F -  What property explains why Flourine and hydrogen refuses to break apart completely?

Strong bases- break apart completely NaOH  Na + + OH - Remember: Groups 1 and 2 except for Be and Mg

Weak bases break apart incompletely Al(OH) 3 Al +3 + OH -

Acid Naming rules -ate polyatomic forms the –ic acid Per_________ic _________ic _________ous Hypo ________ous Examples:

Acid + Base = salt + water Sodium hydroxide + Hydrochloric Acid  Salt: cation comes from the base and the anion from the acid. Neutralization reaction

Sulfuric Acid + Sodium hydroxide  Carbonic Acid + Aluminum hydroxide 

Salts can react in neutralization rx Hydrochloric Acid + Magnesium carbonate  Phosphoric acid + Calcium carbonate  Sulfuric Acid + Calcium carbonate  Molarity math problems

Salt Prediction Salt- a compound formed from the reaction of an acid and a base For each salt predict the acid and base that was used: Cation –from the base; Anion -from the acid Sodium chloride Magnesium phosphate Aluminum nitrate

Net Ionic Strong Acids and Strong Bases break apart Use this fact along with the solubility rules from the solutions chapter. Examples:

Quick review For each salt determine the parent acid and base and strengths for acids 1. Chrominum oxalate Gallium sulfide Write the net ionic reaction for : 2HBr + ZnSO 3  ZnBr 2 + H 2 SO 3

Buffers Buffers are acids or bases that are used to prevent the pH from changing. Bronsted-Lowery definitions for acids and bases explain buffers

How buffers work Buffers works by absorbing excess H + or OH - in a solution. This prevents the pH from changing.

Examples: Antacids work by absorbing excess stomach acid- They contain a buffer that prevents the stomach’s pH from changing too drastically to a basic pH

Baking soda(homemade antacid) is not buffered. The pH is changed to much and the stomach releases more stomach acid and the indigestion process continues.

Other common uses of buffers Fish tanks, blood system, swimming pools

Blood system—real life example Hyperventilation- person breathes too rapidly  Too much CO 2 is lost  pH of the blood increases (too basic)

treatment Breathe into a bag  air is rich with CO 2  causes an increase in the H + and the pH decreases back to normal

Heart Failure Person fails to release CO 2 Too much CO 2 in blood system pH of blood becomes too acidic (low pH)

Treatment IV of sodium bicarbonate(basic salt) Increases the pH back to normal

Amphoteric A substance the can react as an acid or base depending on the chemical it is reacting with.  Examples- Al(OH) 3 Water

pH Water is capable of self ionizing

1.o Liter of water produces 1.0 x moles of H 3 O + and 1.0 x moles of OH - This allows the Ionization constant for water to be calculated

Calculate the H 3 O + and the OH - 1) M HCl2) M NaOH 3) 2.69 x M HBr 4) 4.14 x M KOH

pH is a way of expressing the hydronium ion concentration pH scale 7 is neutral less than 7= acidgreater than 7= base

Calculate the pH for the following: 1) M HCl2) M HBr 3) 5.69 x M HCl

pOH is a way of expressing the hydroxide ion

Calculate the pOH  5.69 x M NaOH  M KOH

Determine the 1) hydronium 2) hydroxide 3) pH4) pOH M HI 7.23 x M LiOH

When given the pH or the pOH the H 3 O + and OH - can be calculated:  H 3 O + = antilog(-pH) or 10 -pH  OH - = antilog (-pOH) or 10 -pOH Remember the pH or pOH must be typed in as a negative number

Calculate the hydronium and hydroxide ion concentration for each of the following:  1) pH = 6.43  2) pOH = 3.43  Identify if the substances are acidic ore basic

Calculate the hydronium and hydroxide ion concentration for each of the following: 1) pH = )pOH = 3.22 Identify if the substances are acidic ore basic

Sample lab problem How many grams of HCl in a 500 mL solution would be needed to make a solution that has a pH of 2.55?  Hint- first calculate the molarity of the hydronium ion. second- calculate the number of grams required to make this Molarity solution. (don’t worry- we are smushing the material)

Answer:

Sample Lab Problem The lab needs a 250 mL solution of.666 M Sodium hydroxide. The only sodium hydroxide available is 5.00 M. How many mL of the 5.00 M solution is needed? (dilution problem from Molarity test)

Sample Lab Problem What is the pH of the 5.00 M solution of NaOH and what is the pH of the.666 M solution of NaOH?

Sample Lab Problem How many grams of Sodium hydroxide would be needed to make 500. mL of a 5.00 M solution?

JUST SMUSHING On the lab sheet- you will have to calculate the hydronium ion, hydroxide ion, pH, pOH and combine these concepts with the Molarity chapter. NO molality on the lab

If the pH of sodium hydroxide is 11.6, what is the pOH?

Calculate the pH of a bottle of sodium hydroxide that has a.0564 M.

Calculate the pH of a bottle of HBr that has a M.

If the pH of a solution is 5.67 Calculate the OH -, H 3 O + for the solution. Show the formulas that you used.