Solutions and Acids and Bases No Pics

8/8/2019 Solutions and Acids and Bases No Pics

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Solutions and Acids and

Bases


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Types of Attractions

Ionic

Covalent

Hydrogen

Van der Waals Forces

Intermolecular force of attraction

Due to uneven sharing of electrons in covalent bonds

Slight attraction between oppositely charged regions of molecules thatare closely packed together

Holds large molecules together


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Hydrophilic and HydrophobicSubstances

A hydrophilic substance is one that has anaffinity (likes!) for water

A hydrophobic substance is one that doesnot have an affinity (does NOT like; scared

of) for water


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Mixtures physically, not chemically mixed compounds

Not necessarily evenly distributed

Homogenous Evenly distributed

Cannot see the different parts

Heterogenous Not uniformly distributed

you can see the parts Solution

Homogenous Mixture components are uniformly distributed

Solutes and solvents

Ex. Salt water Suspension

Mixture of water and non-dissolved material

Some of the most biologically important substancesare both solutions and suspensions

Ex. blood


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How water acts in solution

Occasionally a water moleculedissociates (breaks up) into ions H2O H+ + OH-

This happens to every one watermolecule in a million in pure waternot very common

The H+ immediately reacts with

another water molecule in thesolution to make a HYDRONIUM ionH30+


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Acids and Bases

What do you know?


7/19

Acids

An acid is any substance that increases the H+

concentration of a solution ADDS H+ ions to water

taste sour

turn cabbage juice red

turn blue litmus paper red

Strong acids (LOW pH) Dissociate completely in water

Adds LOTS of H+ ions

Hydrochloric acid HCl

HCl H+ and Cl-

Weak Acids (pH slightly below 7) Partially dissociate in water

Only add a little bit of H+ ions

Coffee, tomato juice, acetic acid

H O//|

-- H C C | \\

-H O

CH3COOH = CH

3COO- + H+


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Bases A base is any substance that reduces the H+ concentration

of a solution

ADDS HYDROXIDE ions (OH-) to water OH- ions bind to any free H+ ions to makea molecule of

water

This does what to the concentration of H+ ions ion thewater?\

DECREASE H+ ion concentration, therefore, making it basic

Characteristics: taste bitter

feels slimy

turns cabbage juice yellow, green or blue depending uponthe solution concentration

turns red litmus paper blue

Strong Bases (pH High- close to 14) Completely dissociate in solution

Adds LOTS of OH- ion to solutions

NaOHsodium hydroxide NaOH Na+ and OH-

Weak Bases


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http://www.chem4kids.com/files/art/ph_scale.gifhttp://www.chem4kids.com/files/art/h_oh_ph.gif


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Strong Acids and Bases

-H C l h yd ro ch lo rica cid

H N O 3 - nitricacidH 2SO4 - sulfuric

acid

-HBr hydrobromicacid-HI hydroiodic acid

HClO4 - perchloricacid

-LiOH lithium hydroxide-NaOH sodium hydroxide

-KOH potassium hydroxide-RbOH rubidium hydroxide-CsOH cesium hydroxide

ISSOCIATE COMPLETELYISSOCIATE COMPLETELYhat do you notice?hat do you notice?


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The pH Scale

The pH of a solution is determined by therelative concentration ofhydrogen ions H+ So it is really measuring how acidic something is

formula is..

pH=-log[H+] Negative means opposite, this is why a low pH has

MORE H+ ions

[x] means concentration

Acidic solutions have pH values less than 7 More H+ ions

Basic solutions have pH values greater than 7 More OH- ions, less H+ ions

Most biological fluids have pH values in theran e of 6 to 8


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LE 3 8


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LE 3-8 H Scale0123456789

1011121314 ve ncleaner

ouseholdbleach

ousehold ammoniailk ofmagnesia

Seawater

ure waterum an b loo d

UrineRainwater

lackcoffeeomatojuice

, ,inegar beer,in ecola

igestive( )tomach,uice lemonjuice

atteryacid

Neutral[H+] = [OH ]


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Buffers

The internal pH of most living cells mustremain close to pH 7

Buffers are substances that minimizechanges in concentrations of H+ and OH-

in a solution Weak acids are a buffer for strong bases

Weak bases are a buffer for strong acids

Most buffers consist of an acid-base pair

that reversibly combines with H+


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Acids and Bases in the LivingThings

Changes in concentrations of H+ andOH- can drastically affect thechemistry of a cell

When you breath

CO2 + H2O H+ + HCO-3

Carbon dioixde water hydrogen ion bicarbonate ion


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The Threat of AcidPrecipitation

Acid precipitation refers to rain, snow, orfog with a pH lower than 5.6

Acid precipitation is caused mainly by themixing of different pollutants with water

in the air Acid precipitation can damage life in lakes

and streams

Effects of acid precipitation on soilchemistry are contributing to the declineof some forests

LE 3 9


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LE 3-9

01234567891011121314

Morebasic

Normalrain

MoreacidicAcidrain

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Solutions and Acids and Bases No Pics