Introduction to Water Flashcards

1
Q

What are some uses of water?

A

1) Grow
2) Wash
3) process
4) dissolve
5) transport
6) digest
7) react

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2
Q

What are the two standard states chemistry and physics typically revolve around ?

A

Pure compounds and controlled reactions

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3
Q

What are colloids?

A

a mixture where tiny particles of one substance are dispersed throughout another, creating a complex system that contributes significantly to the texture, stability, and appearance of many food products
(ex. Milk, cream, egg yolk)

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4
Q

What solvent is used most often?

A

Water

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5
Q

What is a water molecule composed of ?

A

A polar covalently bonded compound containing 2 hydrogen atoms bonded to oxygen by single covalent bonds

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6
Q

Sucrose + water =

A

Molecular state

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7
Q

Salt + water =

A

Ionic state

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8
Q

How is the solid structure of water characterized ?

A

1) Crystalline in nature

2) Even spacing

3) Repeating patterns

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9
Q

What are the 3 properties of water?

A

1) High melting and boiling point

2) High specific heat

3) High latent heat of fusion and vaporization

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10
Q

What is specific heat?

A

Heat required to change 1g by 1 degree Celsius

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11
Q

What is latent heat of fusion and vaporization?

A

The # of calories to convert 1g of ice at 1degree Celsius into liquid at the same temperature or 1g of liquid to vapor at the boiling point

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12
Q

What is a calorie?

A

A unit of heat, measured using a bomb calorimeter

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13
Q

What are the 3 forms of water?

A

1) solid

2) liquid

3) gas

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14
Q

True or false? Very dry foods still contain wate

A

True. (Beans, sugar, salt)

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15
Q

Scientific Utilizations of water

A

1) Enzymatic reactions

2) Digestion

3) microbial growth

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16
Q

What are some characteristics of oxygen?

A

1) very electronegative

2) electrical asymmetry

3) no overall net change

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17
Q

Explain the difference between polar and non- polar

A

Non-polar has less attraction, is electronically equal, has a equal number of positive and negative chargers, and has equally shared electron pairs while polar has an uneven distribution of charges

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18
Q

Dipole-ion interactions use:

A
  • solutes
  • proteins
19
Q

Dipole-dipole interactions use:

A
  • proteins
  • carbohydrates
20
Q

What is the triple point on a phase diagram for water?

A

The specific temperature and pressure at which all three phases of water (solid, liquid, gas) can coexist in equilibrium

21
Q

Why is the phase transition of water important to know?

A

the state of water (solid, liquid, gas) significantly influences the physical properties of food during storage, preparation, and consumption; essentially, knowing how water changes phases allows food scientists to optimize food processing techniques and predict how a food product will behave under different temperature conditions

22
Q

Sublimation =

A

In a vacuum, water (ice) molecules “melt” but change into vapor instead of liquid

23
Q

Density =

A

Mass per unit volume

24
Q

Who discovered displacement of water by weight?

A

Archimedes

25
What are three considerations of water?
1) thermally dense water is a poor conductor 2) heat capacity and dielectric constant for water is high 3) promotes interactions, solubility, and change
26
Molar system-
The gram molecular weight of solute (1 mole) in a liter of solution
27
Molal system-
The gram molecular weight of solute in 1kg of solvent
28
Percent by weight-
The grams of solute present in 100g of solution
29
Percent by volume-
The grams of solute in 100ml of solution
30
According to bronsted-Lowry, acid =, base =
Acid = proton donor Base = proton acceptor
31
Why is titration used?
Easy way to find the endpoint of a reaction
32
How is titration performed?
In titration, a burette is used to deliver a precise amount of an acid or base of KNOWN concentration to a KNOWN volume of a solution with an UNKNOWN concentration
33
What is normality?
How many hydrogen are available for a reaction to take place
34
What happens to vapor pressure when solute is added?
The vapor pressure diagram for solutions shows that vapor pressure is lowered when a solute is added
35
What happens to vapor pressure when solute is added?
The vapor pressure diagram for solutions shows that vapor pressure is lowered when a solute is added
36
What is Raoult’s law?
Psoln = Xsolvent P^o solvent
37
What is the equation for water activity?
Vapor pressure of water in food (partial pressure) / vapor pressure of pure water
38
Hydration -
Combined with water to form a hydrate with the water molecule retained in its molecular states
39
Dehydration -
A process of removing water from a substance or compound
40
Solvent properties -
Capable of dissolving another substance without changing chemical form
41
Solution -
Physically and homogeneous mixture in which the solute is either in an ionic or molecular state of subdivision
42
Hydrolysis -
Decomposition of a chemical compound by reaction with water ; water does not maintain a chemical state such as with the hydrolysis of fats
43
Osmosis -
If separated from pure water by semi-permeable membrane, water molecules will pass through the membrane to equalize the concentration To stop osmosis, apply osmotic pressure Two solutions with equal osmotic pressure - isotonic solutions