Chapter 3: Polar Covalent bonds in water molecules result in hydrogen bonding

What shape does water have on the molecular scale

Wide V with two hydrogen atoms joined by a oxygen atom

With water what atom is more electronegative?

Oxygen

when water is in its water form what bond is very fragile?

The hydrogen bonds

why does it take a lot of energy to make water molecules change from liquid to gas?

Because individual water molecules are polar

What bonds does water have between oxygen and hydrogen?

Polar covalent bonds

what bond does a water molecule have?

Polar

Why does water have the ability to contain lots of heat?

Because It takes a lot of energy to store heat

what are four emergent properties of water that contribute to earths suitability as an environment?

Cohesive behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent

The ability of water molecules to be attracted to other water molecules

cohesion

What is a result of cohesion due to hydrogen bonding?

High surface tension

a measure of how difficult it is to stretch or break the surface of a liquid

Surface tension

how does cohesion help with water and dissolved nutrients in plants?

It transports these things against gravity by getting the water from the roots to the leaves through a network of water conducting cells.

The clinging of one substance to another

adhesion

how does adhesions help water in plants be transported?

As water evaporates from the leaves it pulls the water form the roots to the top fighting against gravity tugging the molecules with the hydrogen bonds adhesion with the cell walls

Explain adhesion and cohesion with a plant?

Adhesion is when the water molecules bond and pull the water with the cell molecules and the cohesion is when the water molecules connect to the other water molecule so that when adhesion happen more water molecules get pulled up

How does after moderate air temperature?

By absorbing heat from the air that is warmer and realeasing heat to air that is cooler.

Why is water effective as a heat bank?

Because it can absorb or release a relatively large amount of heat with only a slight temperature change

the energy of motion

kinetic energy

what energy does anything that moves have?

kinetic energy

The kinetic energy associated with the random movement of atoms or molecules

Thermal energy

Represent the average kinetic energy of the molecules in a body of matter

temperature

What is the difference between thermal energy and kinetic energy?

Thermal energy measures random movement of kinetic energy and temperature does the average kinetic energy meaning thermal energy uses volume to measure and temperature does not

When comparing a pot of coffee to a swimming pool which one has more thermal energy? Why?

The swimming pool because it has a lot more volume

how does thermal energy pass between two objects of different temperatures?

The object that has less thermal energy will gain some from the one that has more thermal energy until they have the same temperature

When thermal energy is transferred form one body of matter to another

heat

the amount of heat it takes to raise the temperature of 1 g of water by 1 degree Celsius

Calories

The quantity of heat required to raise the temperature of 1 kilogram of water by 1 degree Celsius

kilocalorie

How many calorie are in a kilocalorie

1000

What unit of heat measurement is used on food packages

Kilocalorie

How many joule is in a calorie

4.184

How many calorie is in a joule

.239

Is a joule or calorie bigger

A calorie

The amont of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree Celsius

Specific heat

the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state

Heat of vaporization

As a liquid evaporates, the surface of the liquid remains behind cools down. How does this happen and what is it called?

This happens because the “hottest” molecule with the great kinetic energy are most likely to leave as gas and it is called evaporative cooling

Is water more or less dense as a solid or liquid?

Solid

what makes water denser as a solid?

Instead of the molecules getting closer waters molecule get too slow to break the bonds so their molecules just stay the same because their molecules more to slow to break the hydrogen bonds

how is the information that ice floats good for the environment?

If ice were to start sinking in the environment then that means that all forms of water would start to freeze making it impossible for life on earth

A liquid that is completely homogeneous mixture of two or more substances

Solution

Dissolving agent of a solution

solvent

substance that is dissolved

solute

One in which the solute is dissolved in water

Aqueous solution

Any substance that has affinity for water

Hydrophilic

Substance that are non ionic and non polar seem to repel water

Hydrophobic

The sum of the masses of all hte atoms in a molecule

Molecular mass

The number of moles of solute per liter of solution

Molarity

A substance that increases the hydrogen ion concentration of a solution

Acid

A substance that reduces the hydrogen ion concentration of a solution

Base

[H+][OH-]=?

10^-14

-log[H+]=

pH

What happens to H+ concentration when pH decreases

It increases

a substance taht minimizes changes in concentration of H+ and OH- in a solution

Buffer

How does a buffer work?

It accepts hydrogen ions from the solution when they are in excess and donating hydrogen ion to the solution when they have been depleted

what do most buffer solution contain?

Weak acid and it corresponding base which combine reversely with hydrogen ions