understanding acids and bases.ppt 2012

Acids Acids and and

BasesBases

Understanding Acids and Understanding Acids and BasesBases

7.5-8

Baking Soda 8.5 - 9

Lemon Juice 2.5-3

Normal Rain 5.6-6.5

Drain Cleaner (NaOH)

12 - 14

Battery Acid .5-1

Stomach Acid .5-1

Milk 6.5

Ammonia 11-12

Orange Juice 3.5

Cola 2.5-4

SalivaDistilled Water

Tap Water

Vinegar

7 - ish

2.5-3

6 -7.4

Putting it all TogetherPutting it all Together

Characteristics of AcidsCharacteristics of Acids

Taste sourTaste sour

pH less than 7pH less than 7

Corrode MetalCorrode Metal

Conduct electricity very well Conduct electricity very well (bases will also (bases will also conduct electricity but not as well as acids)conduct electricity but not as well as acids)

Characteristics of BasesCharacteristics of Bases

pH greater than 7pH greater than 7

Taste bitterTaste bitter

Good CleanersGood Cleaners

Feel slipperyFeel slippery

Understanding the pH Scale

0 7 14Acidic Basic

Neutral

•The pH scale is a logrithmic scale.

•A difference of one pH unit represents a tenfold change

•A difference of 2 pH units, for example from 6 to 4, would mean that the acidity one hundred times greater.

Check Your Understanding

How many times more acidic is a tomato than coffee?

How many times more acidic is tomato than saliva?

How many times more acidic is lemon juice than coffee?

10

100

1,000

What kinds of What kinds of

Indicators areIndicators are

there?there?

What makes a solution an What makes a solution an acid?acid?

What makes a solution a What makes a solution a base?base?

Is There a Pattern Is There a Pattern Here?Here?

A = HClA = HCl E = E = HNOHNO33

B = HB = H2SOSO4 F = HF = H3BOBO3

C = NaOH G = C = NaOH G = NHNH4OHOH

D = KOHD = KOH H = CaOH H = CaOH

Questions?Questions?

Acid Base ReviewAcid Base Review

What is the pH scale?What is the pH scale?

A numerical scale 0-14 that is used A numerical scale 0-14 that is used to measure how acidic or alkaline a to measure how acidic or alkaline a substance is.substance is.

What is What is phenopthalein?phenopthalein?

A base indicator. It turns A base indicator. It turns bright pink when put into a bright pink when put into a

base.+base.+

What is bromythymol blue?What is bromythymol blue?

An universal indicator. It turns An universal indicator. It turns yellow when placed in an acid. yellow when placed in an acid. Bright blue in base. Mostly used to Bright blue in base. Mostly used to detect carbonic acid.detect carbonic acid.

What is Universal Indicator and What is Universal Indicator and how can you use it to test an how can you use it to test an

unknown solution? unknown solution?

An acid/base indicator. It turns An acid/base indicator. It turns different colors depending upon the different colors depending upon the strength of the acid and base. You strength of the acid and base. You use a color chart to find the number use a color chart to find the number that corresponds to the pH scale.that corresponds to the pH scale.

How does the pH number of a How does the pH number of a strong acid compare to the pH of a strong acid compare to the pH of a

weak acid? weak acid?

A strong acid will have a pH of 0-1. A strong acid will have a pH of 0-1.

A strong base will have a pH of 13-14A strong base will have a pH of 13-14

What is the difference between an What is the difference between an acid and a base? acid and a base?

An acid has a H ion.An acid has a H ion.

A base has a hydroxide ion.A base has a hydroxide ion.

What sort of foods are What sort of foods are acids? acids?

lemons, oranges, anything with citric lemons, oranges, anything with citric acid. Also milk is slightly acidic.acid. Also milk is slightly acidic.

What sort of liquids are What sort of liquids are cleaners? cleaners?

BasesBases

What do acids taste like? What do acids taste like?

soursour

What liquid is neutral? What liquid is neutral?

pure waterpure water

How can you compare strengths of How can you compare strengths of acids using the pH scale? acids using the pH scale?

For every number difference on the pH scale, it For every number difference on the pH scale, it is that many power of ten times more acidic. is that many power of ten times more acidic.

Hard to explain…….. For instance….. If youHard to explain…….. For instance….. If you ’’re re comparing something with a pH of 2 to comparing something with a pH of 2 to something with a pH of 6…. the pH of 2 is ten something with a pH of 6…. the pH of 2 is ten thousand times more acidic than the pH of six.thousand times more acidic than the pH of six.

6-2=4……….. that means it6-2=4……….. that means it’’s 10 to the fourth s 10 to the fourth power stronger. Ten to the fourth is 10,000power stronger. Ten to the fourth is 10,000

What is the pH range of normal What is the pH range of normal rain? rain?

5.6-6.55.6-6.5

What is the pH range of acid What is the pH range of acid rain? rain?

Below 5.6Below 5.6

What acid does carbon dioxide What acid does carbon dioxide form in water? form in water?

Carbonic AcidCarbonic Acid

What is meant by the term What is meant by the term "neutralization"? "neutralization"?

Adding base to an acid until it Adding base to an acid until it becomes pH close to 7becomes pH close to 7