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Biology > pH and Water Lab > Flashcards

pH and Water Lab Flashcards

1
Q

What is the PH of a solution?

A

Measure of its Hydrogen ion (H+) concentraion

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2
Q

What is a neutral PH?

A

A solution with the same amount of H+ as pure water (PH 7) is neutral

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3
Q

Solutions with more H+ than water are given higher or lower PH values? What are they defined as?

A

They have lower PH values and they are defined as acidic.

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4
Q

Solutions with less Hydrogen ion (H+) concentration are given higher or lower PH values? What are they defined as?

A

Higher PH values. Defined as basic or alkaline.

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5
Q

What is the pH Scale?

A

0-14

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6
Q

0, 1, 2, 3, 6, 7, 8, 9, 14. What is the quality and what is a comparable substance?

A

0 is most acidic in quality. 1 is battery acid , 2 stomach acid, 3 vinegar, as comparable substances.

6 is least acidic, saliva comparable substance.

7 is neutral, pure water being a comparable substance.

8 is least basic, sea water being a comparable substance.

9, comparable substance intestinal fluids.

14 is most basic, comparable substance lye (Drano) drain cleaner.

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7
Q

The concentrations of hydroxyl ion (OH-) are equal to what substance? What are they decreased/increased of?

A

Concentrations of the hydroxyl ion (OH-) equal hydrogen ion concentration in pure water. They are decreased in acids and increased in bases.

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8
Q

What does a strong acid have a high and low concentration of?

A

A high concentration of H+ and a low concentration of OH-.

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9
Q

What does a strong base have a high and low concentration of?

A

A low concentration of H+ and a high concentration of OH-.

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10
Q

What do pH values represent in terms of changes?

A

They represent ten-fold changes in ion concentration.

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11
Q

Are water molecules polar or nonpolar?

A

Polar.

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12
Q

What does polar mean?

A

Slight electrochemical charges at each of their four poles, two negative charges on the oxygen atom, and a positive charge on each of the two hydrogen atoms.

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13
Q

How does a weak hydrogen bond get formed?

A

A positive charge on one water molecule forms a weak hydrogen bond with a negative charge on another water molecule. Each water molecule forms four hydrogen bonds with other water molecules.

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14
Q

What did we do in the lab regarding testing pH paper?

A

There were liquid solutions of a variety of household substances on the lab counter tops. We used strips of pH paper with forceps (tweezers) in the solution because the salt on our fingertips could have misconstrued the results of the pH, which produces incorrect results. We recorded these results and placed the used paper strips in the used pH paper container.

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15
Q

How did we do the buffer experiment?

A

We poured 10 ml of milk into a 30 ml beaker and 10 ml of tap water into another. We measured the pH of each using the same pH paper we had had used, and recorded the results. We added 5 drops of hydrochloric acid (HC1) to each beaker and stirred and measured their pH’s again. Concluding this experiment, we added 10 drops of a weak base called sodium hydroxide, NaOH to each beaker and stirred and measured the pH again.

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16
Q

Where do soft drinks get their carbonation from?

A

From injecting carbon dioxide gas into the beverage.

17
Q

How do beer and wine have their natural carbonation?

A

Carbon dioxide being produced by yeast during fermentation gives beer and wine their natural carbonation.

18
Q

What happens when carbon dioxide and water are mixed? What is the reaction?

A

A weak acid (carbonic acid) is formed. This happens in all carbonated beverages, CO2 + H20 = H2CO3

19
Q

What happens when rainwater falls through the air?

A

The air becomes both naturally carbonated and acidified since Earth’s atmosphere is one percent carbon dioxide.

20
Q

What do buffers do?

A

Buffers have the ability to resist pH change by chemically incorporating excess H+ or donating H+ when it is depleted.

21
Q

What is the specific heat of a substance?

A

The amount of heat necessary to raise the temperature of one gram of that substance one degree Centigrade.

22
Q

What do substances with high specific heats require?

A

A lot of heat to raise their temperatures. They are hard to heat up and hard to cool off.

23
Q

What is the heat of vaporization?

A

The amount of heat necessary to cause a liquid to evaporate, change in state from a liquid to a gas.

24
Q

What is Capillary Action?

A

The way in which water is drawn up by tubes with small diameters which involves cohesion and adhesion.

25
Q

What does adhesion do with water?

A

Adhesion causes water molecules to cling to the sides of small pores, cylinders, and other tiny spaces.

26
Q

What does cohesion do with water?

A

Cohesion enables water molecules to pull other water molecules up behind them.

27
Q

Cohesion

A

The ability of water molecules to bond to each other is cohesion, because strong forces cause waters high specific heat and vaporization by making individual water molecules that are resistant to movement and difficult to release into the air.

28
Q

What is surface tension?

A

Cohesion allows water molecules to form a membrane-like outer layer that is known as surface tension, which is why mosquitos are able to stand on water. Water molecules at the surface are unable to form hydrogen bonds above themselves, so the unused bonding capacity is filled on a plane parallel to the water’s surface, which this extra cohesion layer makes the surface tension,

29
Q

What is adhesion?

A

Charged poles of water molecules being able to bond to other substances, assuming those substances are also charged or polar. Adhesion enables water to wet other substances, through a process of adsorption. Adhesion also enables water molecules to hold other molecules and ions in solution.

30
Q

What is the Heat of Vaporization?

A

The amount of heat necessary to cause a liquid to evaporate. Change in state from a liquid to a gas.

31
Q

Why is water slow to evaporate?

A

Because water has a very high heat of vaporization

32
Q

Why is water an efficient evaporative cooler?

A

Because it take a lot of heat for water to evaporate. Water can take away more heat for longer than the same volume of alcohol

33
Q

What is the specific heat of a substance?

A

The specific heat of a substance is the amount of heat that’s necessary to raise the temperature of that substance by one degree centigrade. They’re hard to heat up, and hard to cool off.

34
Q

What is Adhesion?

A

Adhesion causes water molecules to clung to the sides of small pores, cylinders, and other tiny spaces. The charged poles of water molecules can bond to charged or polar substances, which is also Adhesion. Adhesion enables water to wet other substances, which is a process known as adsorption. Also enables water molecules to hold other molecules and ions in solution.

35
Q

What is Cohesion?

A

Cohesion enables water molecules to pull other water molecules up behind them. Water molecules being able to bond to each other is cohesion. These strong forces causes waters high specific heat and heat of vaporization by making individual water molecules resistant to movement and difficult to release into the air. Cohesion also allows water molecules to form a semi membrane like outer layer known as surface tension.

36
Q

What is Surface Tension?

A

Cohesion allows water molecules to form an almost membrane like outer layer known as surface tension, why mosquitos are able to stand on water.

37
Q

What makes up Surface Tension?

A

Water molecules at the surface are unable to form Hydrogen Bonds above themselves, so the unused bonding capacity is filled on a plane parallel to the waters surface. This extra cohesive layer makes the surface tensions

38
Q

What is Adsorption?

A

Adhesion enables water to wet other substances, which is a process known as Adsorption.

39
Q

What kind of substances are water, alcohol, plastic, and glass?

A

Water is polar, alcohol is weakly polar, plastic is nonpolar, and glass is electrically is an electrically charged compound.

Biology (7 decks)

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