2.5 Biology

Whenever two objects of different temperature are brought together, thermal energy passes from the ___________ to the ________ object until the two are the same temperature. Explain and example?

1. Warmer 2. cooler Molecules in the cooler object speed up at the expense of the thermal energy of the warmer object. An ice cube cools a drink not by adding coldness to the liquid but by absorbing thermal energy from the liquid as the ice itself melts.

What percent of cells are water?

70-95% water

Calorie

A calorie is the amount of heat it takes to raise the temperature of 1 g of water by 1°C. Conversely, a calorie is also the amount of heat that 1 g of water releases when it cools by 1°C

Kilocalorie

A kilocalorie (kcal), 1,000 cal, is the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1°C. This is what we actually see on food packages

Solution

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

Temp is not the same thing as thermal energy, what is temperature?

A measure in degrees of the AVERAGE kinetic energy (thermal energy) of the molecules in a body of matter, regardless of volume, whereas the thermal energy of a body of matter reflects the total kinetic energy and thus depends on the matter's volume.

surface tension

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

Buffer

A solution that minimizes changes in pH when extraneous acids or bases are added to the solution. It does so by accepting hydrogen ions from the solution when they are in excess and donating hydrogen ions to the solution when they have been depleted. Most buffer solutions contain a weak acid and its corresponding base, which combine reversibly with hydrogen ions.

Base

A substance that decreases the hydrogen ion concentration in a solution.

Acid

A substance that increases the hydrogen ion concentration of a solution.

Solute

A substance that is dissolved in a solution.

The water molecule that lost a proton is now a hydroxide ion, which is...

A water molecule that has lost its proton, OH-1

Joule

Another energy unit used in this book is the joule (J). One joule equals 0.239 cal; one calorie equals 4.184 J.

How does cohesion work against gravity, process of cohesion and evaporation:

As water evaporates from a leaf, hydrogen bonds cause water molecules leaving the veins to tug on molecules farther down, and the upward pull is transmitted through the water-conducting cells all the way to the roots. Adhesion of water to cell walls by hydrogen bonds helps counter the downward pull of gravity.

Explain why water has a high specific energy:

Can be traced to hydrogen bonds. Atoms must be exposed to heat in order to break,and for them to form, they must also be exposed to heat. A calorie of heat causes a relatively small change in the temperature of water because much of the heat is used to disrupt hydrogen bonds. And when the temperature of water drops slightly, many additional hydrogen bonds form, releasing a considerable amount of energy in the form of heat.

Hydrophilic

Having an affinity for water. Not always soluable, even tho it attracts water

Hydrophobic

Having an aversion to water; tending to coalesce and form droplets in water. Non polar and non ionic repel

Water, ionic or covalent, polar or not?

Polar covalent bonds, oxygen pulls harder than hydrogen atoms The unequal sharing of electrons and water's V-like shape make it a polar molecule, a molecule with unequal sharing of electrons throughout the molecule O is B- (two spots where it pulls harder), H is A+

Which has more thermal energy, a swimming pool or a hot cup of coffee?

Pool, because of its relative massive volume. In total, the slower movement of ALL those molecules trumps the faster movement of the tiny cup of coffee.

Does a compound have to be ionic to dissolve in water?

Such compounds dissolve when water molecules surround each of the solute molecules, forming hydrogen bonds with them. Even molecules as large as proteins can dissolve in water if they have ionic and polar regions on their surface.

Adhesion

The clinging of one substance to another, such as water to plant cell walls, in this case by means of hydrogen bonds.

Anything that moves has Kinetic Energy, what is it?

The energy associated with the relative motion of objects. Moving matter can perform work by imparting motion to other matter. The energy of motion.

evaporative cooling

The process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous state. It is as if the 100 fastest runners at a college transferred to another school; the average speed of the remaining students would decline.

Describe the hydrogen bonds between different water molecules

The properties of water arise from attractions between oppositely charged atoms of different water molecules: The partially positive hydrogen of one molecule is attracted to the partially negative oxygen of a nearby molecule. HYDROGEN BONDING GIVES WATER EMERGENT PROPERTIES UPON FORMING NEW MOLECULES>>>>> The extraordinary properties of water emerge from this hydrogen bonding, which organizes water molecules into a higher level of structural order

What happens to that proton?

The proton binds to the other water molecule, making that molecule a hydronium ion, H3O+, usually just repped as H+

Molecular mass

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

Moderation of temperature

Water is able to absorb heat from a source of high temp, store it like a bank, and transfer it to a cooler place with a small change in its own temperature.

Water's specific heat

We already know water's specific heat because we have defined a calorie as the amount of heat that causes 1 g of water to change its temperature by 1°C. Therefore, the specific heat of water is 1 calorie per gram per degree Celsius, abbreviated as 1 cal/(g · °C) Water's specific heat is high, pot example in book but this is clear. water will change its temperature less than other liquids when it absorbs or loses a given amount of heat.

We use the measurement Mole for molecular mass. What is a mole

We take the og molecular mass, in daltons, and convert to Moles using Avogadro's number, 6.02x10^23 daltons in one gram

Why does water have an unusually high surface tension

Where water and air meet, there is an arrangement of hydrogen bonds. On the surface of the water, hydrogen bonds take place between one another, as well as to the water below the surface, but not to the air above. This asymmetry makes the tension high.

Occasionally, a hydrogen atom participating in a hydrogen bond between two water molecules shifts from one molecule to the other. When this happens, the hydrogen atom leaves its electron behind, and what is actually transferred is a Hydrogen Ion, which is...

a positively charged ion (H+) formed of a hydrogen atom that has lost its electron

Water is the solvent of....

all life

Ocean acidification

decreasing pH of ocean waters due to absorption of excess atmospheric CO2 from the burning of fossil fuels

Thermal energy

kinetic energy associated with the random movement of atoms or molecules; energy in its most random form, see also as heat

Water is one of the few substances that are ____________ dense as a solid than as a liquid. Why is this?

less While other materials contract and become denser when they solidify, water expands. As the temperature falls from 4°C to 0°C, water begins to freeze because more and more of its molecules are moving too slowly to break hydrogen bonds

pH Scale

measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14 0-6=acidic 7=neutral, water 8-14=basic

Specific Heat

the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C. Specific heat can be thought of as a measure of how well a substance resists changing its temperature when it absorbs or releases heat.

Cohesion

the linking together of like molecules, often by hydrogen bonds Water molecules stay close to each other as a result of hydrogen bonding. At any given moment, many of the molecules in liquid water are linked by multiple hydrogen bonds. These linkages make water more structured than most other liquids Water sticks together

Molarity

the number of moles of solute per liter of solution

Heat of Vaporization

the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state. For the same reason it has a high specific heat, water has a high vaporization temp; To evaporate 1 g of water at 25°C, about 580 cal of heat is needed—nearly double the amount needed to vaporize a gram of alcohol, for example. This is an emergent property resulting in the strength between hydrogen bonds of water.

acqueous solution

the solute is dissolved in water; water is the solvent

Hydrogen Shell

the sphere of water molecules around each dissolved ion Salt in water, negative oxygen is attracted to NaCl cation, and posetive charge hydrogen attracted to negative charge anion. Do universal solevent property of water is due again to hydrogen bonds

Solevent

the substance in which the solute dissolves; the dissolving agent

Heat

thermal energy in transfer from one body of matter to another