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CSU / Engineering / Life 102 / Whata re the characteristics of water when cohesiveness is present?

Whata re the characteristics of water when cohesiveness is present?

Whata re the characteristics of water when cohesiveness is present?


School: Colorado State University
Department: Engineering
Course: Attributes of Living Systems (GT-SC1)
Professor: Erik arthun
Term: Spring 2020
Tags: Study Guide, life, LIFE102, Science, and Life Science
Cost: 50
Name: Exam 2 Study Guide
Description: This study guide goes into terms and key ides needed for the second exam. It also includes page numbers to reference in the textbook for each idea
Uploaded: 02/22/2020
3 Pages 33 Views 2 Unlocks

Covalent Bonds

Whata re the characteristics of water when cohesiveness is present?

Polar covalent bond­ electrons not equally shared between molecules 

Cohesiveness of Water

o Cohesion also means that water has a high surface tension  

o this is why it hurts to belly flop, because all these weak hydrogen bonds together  make a strong surface

o water moderates changes in temperature

o water has an unusually high specific heat 

o amount of energy required to change 1g of water by 1 degree Celsius

Because of the hydrogen bonds:

o Water has a high heat of vaporization

o As a liquid evaporates, its remaining surface cools, a process called evaporative  cooling 

What do hydrogen bonds do to water?

o This is why we sweat, as the water evaporates, the water takes with it heat from  the core

 Water is most dense at 4 degrees Celsius, not Zero

o Frozen water floats on liquid water; the water Is most dense just above freezing  point

o Hydrogen bonds stabilize at 0 degrees and molecules spread apart from each  other, this causes the ice to float on top of liquid water

 If water sank when frozen, bodies of water would eventually freeze 

completely solid, making like on earth impossible, because there would be little to no liquid bodies of water

 Ice on top also insulates the water below it, keeping it from coming into  contact with the cold air above and preventing it from freezing, to allow 

life to continue below the frozen surface

How does ph affect living organisms?

 Water is a Polar Solvent 

 Hydrophilic substances:

o High affinity for water

 Ions and polar molecules

 Hydrophobic Substances

o Low affinity for water

 Nonpolar molecules / nonionic elements Don't forget about the age old question of What is the formula for molality?

 Ex: oil will not mix with water, you can shake it and get little blobs of oil,  but after time it will completely separate again, the oil pieces connect back to each other because it is protecting the inner molecules of oil from 

coming in contact with water

 Compounds dissolve in water to form a Solution 

o Most biological reactions occur in water 

Measuring Chemicals in a Solution

o Solvent – the dissolving agent of a solution Don't forget about the age old question of How are vascular plants characterized?
If you want to learn more check out What are example of morphological data?

o Solute – the substance that is dissolved

 Concentration – how much of the solute is present per volume of solvent in moles (Molar  (M))

 1M = 1 mole of solute per liter of solvent

pH Affects Living Organisms

 A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other 

o The hydrogen atom leaves its electron behind and is transferred as a proton, or  hydrogen

 Pure water – H+ and OH­ concentrations are EQUAL [H+] = [OH­]

pH = ­log[H=]

pH = A measure of the concentration of H+ ions in solutions [H+]

Pure water: [H+] = 10^­7 M ­> pH= 7

The greater [H+], the more acidic the solution is

pH < 7 – acidic


pH = 7 ­neutral

pH > 7 basic

For each change in pH by 1 unit, [H+] changes 10­fold Don't forget about the age old question of What is illustrated by circular flow diagram?


Cola – pH 3 = [H+} = 10^3M

Pure Water – pH 7 = [H+] = 10^7M

Cola is 10,000 more acidic than pure water

BY changing the concentrations of hydrogen and hydroxide ions in solution Acid: any substance the increases the [H+] of a solution

Base: Any substance that reduces the [H+] of a solution We also discuss several other topics like What does mead believe about the concept of self?

Controlling pH is important for cells Don't forget about the age old question of What are the required sections of a research article?

Biological reactions have an optimal pH (6­8)

Chapter 3: Organic Molecules

Carbon­based molecules

The dry matter of organisms consists mainly of organic molecules  Advantage of Carbon as a building block for life

o Carbon is TETRAVALENT 

 Needs 4 electrons to fill valence shell

 Capable of making 4 chemical bonds

 Large, complex, & Diverse molecules


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