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Biology 1 > Unit 1 (Chapter 2, Part 3) pH > Flashcards

Unit 1 (Chapter 2, Part 3) pH Flashcards

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1
Q

What is the liquid form of H2O?

A

Water

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2
Q

The percentages 70%, 80%, and 90% make up water in what organs and substances in the body? (3)

A

Estimated

Brain (70%)
Blood (80%)
Lungs (90%)

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3
Q

What is the difference between intracellular and extracellular fluid?

A

Intracellular fluid is inside the cell while extracellular fluid is outside the cell.

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4
Q

What is a solute?

A

A substance dissolved in a liquid.

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5
Q

What is a solvent?

A

A liquid in which a solute is dissolved.

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6
Q

What is a liquid that contains one or more dissolved solutes?

A

A solution

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7
Q

What is an aqueous solution?

A

A solution made with water.

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8
Q

Why does table salt dissolve in water?

A

The hydrogen and oxygen atoms in a water molecule are a polar covalent bond. With the oxygen atom having a slight negative charge and the hydrogen atoms having a slight positive charge, a reaction happens with the ion, Na+Cl-.

The partially negatively charged oxygen atoms of water attract Na+ and the partially positively charged hydrogen atoms attract to Cl-

Clusters of water molecules surround the ions which allow Na+ and Cl- to separate from each other and enter the water — that is dissolve.

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9
Q

Generally, what type of bonds in molecules dissolve in water?

A

Those that contain ionic and/or polar covalent bonds.

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10
Q

What does hydrophilic mean?

A

Refers to molecules that contain ionic and/or polar covalent bonds and will dissolve in water.

“Water-loving”

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11
Q

What does hydrophobic mean?

A

Refers to molecules that do not have partial charges and therefore are not attracted to water molecules. Such molecules are composed predominately of carbon and hydrogen and are relatively insoluble in water.

“Water-fearing” Ex. Vegetable oil

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12
Q

What refers to molecules containing a hydrophobic region and a hydrophilic region?

A

Amphipathic

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13
Q

What is the sphere formed from the aggregation of long amphipathic molecules when they are mixed with water?

A

Micelle

The polar regions are on the surface and in contact with water and the nonpolar regions are in the center.

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14
Q

What is a popular example of a amphipathic molecule used today?

A

Detergent. They have polar and non polar ends.

They form micelles that help dissolve the oils and nonpolar molecules found in dirt.

Oils on your skin dissolve in the nonpolar regions of the detergent micelles, and the polar ends help the detergent rinse off in water, taking the oil with it.

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15
Q

In addition to micelles. amphipathic molecules may form structures consisting of double layers called what?

A

Bilayers.

These have two hydrophilic surfaces facing outside, in contact with water, and a hydrophobic interior. This plays a key role in cell membrane structure.

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16
Q

What is the amount of solute dissolved in a unit volume of solution?

A

The concentration

For example, if 1 gram (g) of NaCl was dissolved in enough water to make 1 liter (L) of solution, we would say that its solute concentration is 1 g/L.

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17
Q

What is the better way to describe solute concentration?

A

Since molecules are of different masses, the best way to describe solute concentration is according to the moles of dissolved solute per volume of solution.

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18
Q

What three things must you know to determine the solute concentration?

A

1 - The amount of dissolved solute
2 - The molecular mass of the dissolved solute
3 - The volume of the solution

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19
Q

What is molecular mass?

A

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

For example:

Glucose (C6H12O6) has a molecular mass of 180.

([6x12] + [12x1] + [6x16] = 180)

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20
Q

What is 1 mole of a substance?

A

It is the amount of the substance in grams equal to its atomic or molecular mass.

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21
Q

What is the molarity of a solution?

A

The number of moles of a solute dissolved in 1 L of water.

For example:

Since we know the molar mass of a glucose molecule is 180 then 1 mole of glucose is 180g. With that said, if we place 1 mole of glucose within 1 L of water, the molarity of the solution is 1 molar solution of glucose.

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22
Q

What is a term used to describe a solution’s molarity?

A

Molar

A 1 molar solution contains 1 mole of solute dissolved in enough water to make 1 L of solution.

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23
Q

How would you write 1 mol/L solution?

A

1 M (M stands for molar)

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24
Q

So how would write a molar solution if 90 g of glucose was dissolved in 1 L of water?

A

0.5 mol/L or 0.5 M

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25
Q

What are the exponent values for millimoles (mM), micromoles (uM), nanomoles (nM), and picomoles (pM)?

A

10^-3, 10^-6, 10^-9, and 10^12.

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26
Q

What three states does water exist?

A

Solid (ice), liquid (water), and gas (water vapor).

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27
Q

What are the hydrogen bonds doing in water.

A

Since they are really weak, they are continuously being formed, broken, and formed again,

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28
Q

What happens to water when temperature increases?

A

The rate at which hydrogen bonds break increases, and molecules of water escape into the gaseous state, becoming water vapor.

29
Q

What happens to water when temperature falls?

A

Hydrogen bonds are broken less frequently, so larger and larger clusters of water molecules are formed.

30
Q

At what temperature does water freeze into a crystalline matrix—ice?

A

0 degree Celsius or 32 degrees Fahrenheit.

31
Q

Why does ice float in water?

A

Because when H2O freezes, the molecules in ice tend to lie in a more orderly and open arrangement, that is, with greater intermolecular distances, which makes ice less dense than water.

32
Q

T/F Ice is more likely to participate in most chemical reactions.

A

False.

33
Q

What do you need in order to make a change in state such as changes between solid, liquid, and gaseous states in H2O?

A

Input or release of energy.

34
Q

What is heat of vaporization?

A

The heat required to vaporize 1 mole of any substance at its boiling point under pressure.

This point is high for water because of the large number of hydrogen bonds.

35
Q

Fun Fact: It takes five times as much heat to vaporize water than it does to raise the temperature of water from 0 degrees Celsius to 100 degrees Celsius.

A

(No answer)

36
Q

What is heat of fusion?

A

The amount of heat energy that must be withdrawn or released from a substance to cause it to change from the liquid to the solid state.

This value for water is also high.

37
Q

What is the amount of energy required to raise the temperature of 1 gram of substance by 1 degree Celsius?

A

Specific heat.

38
Q

What is the amount of heat required to raise the temperature of an entire object or amount of substance?

A

Heat capacity.

39
Q

Scenario: Apply the specific heat and heat capacity concepts to a large and small beakers filled with water.

A

A large beaker of distilled water has a greater heat capacity than a small beaker of distilled water.

However, the water in both beakers has the same specific heat.

40
Q

What is a modern day example of specific heat and heat capacity in nature?

A

Hence why the oceans are much more stable in temperature versus inland bodies or water and their temperatures.

Not surprisingly, therefore, living organisms have evolved to function best within a range of temperatures consistent with the liquid phase of water.

41
Q

What is colligative property of a solution?

A

It is the property of a solution that depends only on the total number of dissolved solute particles.

This is total number, NOT on the specific type of solute.

42
Q

What is the relationship of the state of water and its colligative property?

A

Pure water will free at 0 degrees Celsius and vaporize at 100 degrees Celsius.

The addition of solutes to water decreases its freezing point and raises its boiling point.

43
Q

What are (2) examples today that highlight the colligative property in water?

A

Antifreeze. By adding the compound, ethylene glycol, to water in a radiator, it prevents the liquid from freezing.

Additionally, the presence of large amounts of solutes partly explains why the oceans do not freeze when temperature falls below 0 degrees Celsius.

44
Q

What is the general type of chemical reaction that water participates in?

A

R = group of atoms (–) = covalent bond

R1–R2 + H–O–H —-> R1–OH + H–R2

  • A covalent bond is broken in each reactant (the groups of atoms and water molecule), and they form new covalent bonds.
  • This reaction is known as hydrolysis reactions.
45
Q

What is a hydrolysis reaction?

A

A chemical reaction that utilizes water to break apart other molecules.

Hydro meaning water, lysis meaning to break apart in Greek.

46
Q

What are some of the amazing functions of water in nature (5)?

A

1 - Water is used to eliminate soluble wastes in blood through the kidneys.

  1. Plants wilt because the lack of water
  2. Evaporation helps some animals dissipate body heat.
  3. Cohesive force of water molecules aids in the movement of fluid through vessels in plants.
  4. Water in saliva serves as a lubricant during or anticipation of feeding.
47
Q

What is the conversion of water from the liquid to the gaseous state at normal temperatures?

A

Evaporation.

Animals use evaporation as a means of losing excess body heat. The best way to understand this is, with any volume of water at any temperature, there are vibrating water molecules with higher energy than others. Those with the highest energy, break their bonds, and escape in a gaseous state.

48
Q

What is the ability of like molecules to noncovalently bind to each other; the attraction of water molecules to each other?

A

Cohesion.

Water exhibits a strong cohesion due to hydrogen bonding. This aids in the movement of water through the vessels of plants.

49
Q

What is the ability of two different substances to bind to each other; the ability of water to be attracted to, and thereby adhere to, a surface that is not electrically neutral?

A

Adhesion

For example, the adhesive properties of water allow it to coat the surfaces of the digestive tract of animals and act as a lubricant for the passage of food.

50
Q

What is the measure of how difficult it is to break the interface between a liquid and air?

A

Surface tension.

This is what causes water to form droplets. The surface water molecules attract each other into a configuration (roughly that of a sphere) which reduces the number of water molecules in contact with the air.

You can see this by overfilling a cup, and seeing the water bulge above the rim. Likewise, why a water strider can “walk” on water.

51
Q

What does pure water have the ability to ionize a very small extent into?

A

Hydroxide ions (OH-) and hydrogen ions (H+)

52
Q

What is an anion with the formula OH-?

What is a cation with the formula H+?

A

Hydroxide ion (Proton acceptors and bases)

Hydrogen ion (Proton donors and acids)

53
Q

What is the concentrations of H+ and OH- in pure water?

A

10^-7 mol/L, or 10-7 M.

54
Q

Inherent property: At what temperature is the product of concentrations of H+ and OH- always 10^-14 M?

A

25 degrees Celsius

Therefore, in pure water, [H+][OH-] = [10^-7 M][10^-7] = 10^-14 M

55
Q

How are the concentrations of these ions, H+ and OH-, altered?

A

When substances within the water release or absorb these ions.

56
Q

What is a molecule that releases hydrogen ions (H+) in a solution?

A

Acids. Acids increase the concentration of H+ in a concentration.

Ex.

Hydrochloric acid (HCI) is a strong acid because it completely disassociates H+ and Cl- when added to water. (note one direction arrow)

HCI —–> H+ + Cl- (chloride ion)

Carbonic acid (H2CO3) is a weak acid because some it remains in the H2CO3 state when dissolved in water (not bidirectional arrow)

H2CO3 H+ + HCO3- (bicarbonate ion)

57
Q

What molecule, that when dissolved in water, lowers the H+ concentration AND is a component of nucleotides that is a single or double ring or carbon and nitrogen atoms?

A

Bases. Bases have an opposite effect when dissolved in water–it decreases the concentration of H+ concentration. This can occur in different ways.

Ex.

Sodium Hydroxide (NaOH), release OH- when dissolved in water.

NaOH ——> Na+ (sodium ion) + OH-

Recalling that the product of H+ and OH- is always 10^-14 M, when a base raises OH- concentration, some of the hydrogen ions bind to these hydroxide ions to form water.

Therefore, increasing the OH- concentration lowers the H+ concentration.

NH3 (ammonia) + H2O NH4+ (ammonium ion) + OH-

In this case, NH3 increases OH- concentration by removing H+ from H2O. Both lower the concentration of H+

58
Q

How do scientists describe the concentrations of H+ and OH- ions which additions of acids and bases over a broad range?

A

The concentration is expressed as the solution’s pH.

pH is the mathematical expression of a solution’s hydrogen ion (H+) concentration, defined as the negative logarithm to the base 10 of the H+ concentration.

pH = -log10 [H+]

59
Q

What exactly does pH = -log10 [H+]?

A

A solution with an H+ concentration of 10^-7 M has a pH of 7.

A concentration of 10^-7 M is the same as 0.1 micromolars.

A solution in which H+ = 10^-6 M has a pH of 6.

A concentration of 10^-6 M is the same as 1.0 micromolars.

60
Q

At what pH is a solution considered to be acidic since it contains more H+ ions than OH- ions?

A

6

As acidity increases, pH decreases.

61
Q

At what pH is a solution considered to be neutral since it contains the same amount of H+ and OH- ions?

A

7

A solution above 7 is considered to be alkaline.

62
Q

What does a change in 1 pH unit represent in H+ concentration?

A

10-fold difference

63
Q

Scenario: The plant life is sparse because the soil is very acidic. If the pH of the soil were 5.0, what would the concentration be?

A

When you have a pH of 5, the H+ concentration is 10^-5.

This can be calculated by the equation pH = -log10[H+]

From this, you can also determine that the OH- concentration must be 10^-9 M, because the product of the H+ and OH- concentrations must be equal to 10^-14.

64
Q

What can the pH of a solution affect?

A

1 - The shapes and functions of molecules
2 - The rates of many chemical reactions
3 - The ability of two molecules to bind to each other
4 - The ability of ions and molecules to dissolve in water

65
Q

What is typically the pH range for living cells?

A

pH ranges from 6.5 to 7.8.

Blood has a range of about pH 7.35-7.45

66
Q

What does pH and disease have in common?

A

When pH is decreased and increased by a few tenths of a unit, the enzymes needed in the body, especially in kidney disease, for normal metabolism can no longer function optimally, leading to additional symptoms.

67
Q

What organ secretes regulatory acidic and alkaline compounds to fix unbalanced pH?

A

Kidneys

68
Q

What is an acid-base pair that minimizes pH fluctuation in the fluids of living organisms?

A

Buffers. They can raise or lower pH as needed.

Ex.

CO2 + H2O H2CO3 (carbonic acid) H+ + HCO3- (bicarbonate ion)

If pH increases (H+ decreases), the reaction proceeds from left to right. Carbon dioxide combines with water to make carbonic acid, then the carbonic acid dissociates into H+ and HCO3-. This increases H+ concentration and thereby decreases pH.

The action then runs in reverse if the pH is decreased and there is too much H+. (This chemical reaction is when CO2 is exhaled from the lungs) It removes H+ in the blood and restores it to normal pH.

Biology 1 (37 decks)

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