chem ch6

Properties of acids

• sour taste

• Conducts electricity

• Turn blue litmus- red

Reacts with active metals

• neutralizes base

• Less than 7 on scale

Properties of bases

• bitter taste

• Conducts electricity Turn

• Turn red litmus to blue

• Ph greater than 7.

• Neutralizes acids

• Feels slippery

• Ionic compound

The hudronium ion

H+ ion reacts with water.

Meaning of ph

Measures acidity(h30+ concentration)

Meaning of poh

Measure basicity (oh- concentration)

Describe the ph scale

• less than 7- acid

• At 7- neutral

• Greater than 7- basic

Formula to convert ph to hydronium ion

(H30+)= 10 to power - ph.

• take negative of ph

• Raise 10 to that power

• Ans- 1.0 x raised power.

• ex: 1.0 × 10-5.M

lower ph= higher (h30+)

Each step down in ph- 10x more hydronium.

Formula to convert poh to hydroxide ion

(Oh-)= 10 to power of - poh.

Steps

• take the negative of the poh.

• Raise 10 to that power.

Ex:

Poh=7

(Oh-) = 10-7 =1.0 × 10-7M.

Neutral.

Lower poh- more oh- = more basic.

Higher poh- less oh- = more acidic.

Formula to help find poh

Explain the usefulness of inidcators

• shows whether a solution is acidic or basic.

• Changes color at certain ph ranges.

Identify common indicators(and abbre. In acidic or basic form.)

• litmus : red(acidic) , blue (base)

• Phenolpthalein: colourless ( acidic), pink (base)

• Bromothymol blue: yellow (acidic) , blue ( base)

How to estimate ph using color of indicator

• match observed color with ph range.

• Give approx. ph, not exact.

Express acids in terms of producing hydronium or hydroxide

Acids

Express bases as producing hydronium or hydroxide ions

Define a neutralization reaction

• the reaction between an acid and a base.

• Normally a double replacement reaction.

Ex: acid + base - salt + water.

Define strong acids (in terms of dissociation and ionization %)

• An acid that completely dissociates (ionizes) in water.

• No acid molecules left over.

Define strong bases

• a base that completely dissociates (ionizes) in water; meaning it fully breaks apart into ions in solution.

• Most are metal hydroxides.

• Ex: both=( b+) + (oh-)

Define polyprotic acids with ex:

• an acid that cab release more than one h+(hydrogen ion) per molecule when it dissolves in water.

• Ex: diprotic acid(2 h+ ions); triprotic acids( 3 h+ ions).

Define polyprotic bases with ex:

Bases that can accept more than one proton (h+)

Arrhenius definitions(acids and bases)

• acids ionize in solution to form hydrogen ions

• Bases dissociate in solution to form hydroxide ions.

The hydrated proton

Ph meters