Chemistry II test Flashcards
Define and/or explain the following laws
1) 1st law of thermodynamics
Any decrease of energy in a given region of space (system) must be exactly balanced by an increase of energy in another region of space (surroundings)
Define and/or explain the following laws
2) 2nd law of thermodynamics
Entropy is “nearly” conserved, which means any decrease of entropy in a given region of space is almost balanced by an increase in another region. In an isolated system, the entropy never decreases.
Define and/or explain the following laws
3) 3rd law of thermodynamics
It is impossible for any process, no matter how idealized, to reduce the entropy of a system to its absolute-zero value in a finite number of operations.
Define and/or explain the following laws
4) Zeroth law of thermodynamics
If A↔B and C↔B, then A↔B
Define and/or explain the following laws
5) Raoult’s law
Vapor pressure is the sum of the partial pressures.
Define and/or explain the following laws
6) Avogadro’s law
Equal volumes of any two gases at the same temperature and pressure contain the same number of molecules.
Define and/or explain the following laws
7) Ideal gas law
pV = nRT
Pressure, p Volume, V Number of moles, n The gas constant, R The temperature, T
Define and/or explain the following laws
8) Henry’s law
(solubility of gases in liquids)
The solubility of a gas I proportional to the partial pressure of the gas above the solution.
Define and/or explain the following laws
9) Dalton’s law of partial pressure *
The total pressure is given by the sum of individual gas pressure.
Define and/or explain the following laws
10) Boyle’s law *
As volume increases, the pressure of the gas decreases in portion.
Define and/or explain the following laws
11) Charles’ law *
As absolute temperature increases, the volume of the gas also increases in portion.
Define and/or explain the following laws
12) Stefan-Boltzmann law *
The thermal energy radiated by a blackbody radiator per second per unit area is proportional to the fourth power of the absolute temperature and is given by
P/A= σT^4 j/ m^2s
Define/explain the following
1) Reference electrodes (also give examples)
The e. p. of a reference electrode remains constant during the operation of the cell at a given temperature
(e.g. Ag/AgCl-, or the calomel, Hg/Hg2Cl2- electrode).
Define/explain the following
2) Boiling point of liquids
The temperature at which the vapour pressure of a liquid equals the external pressure.
Define/explain the following
3) Critical temperature
The temperature above which it is impossible to liquefy the gas, no matter how high the applied pressure.
Define/explain the following
4) Critical pressure
The minimum pressure needed to liquefy the gas at its critical temperature.
Define/explain the following
5) Gibbs energy (also give equation and the second equation with the relationship to the equilibrium constant)
∆G =∆H - T x ∆S G= Gibbs energy H= Enthalpy T=Temperature S=Entropy
Gibbs energy change combines enthalpy and entropy into a single state function.
∆G =-RTln(K)
Define/explain the following
6) Strong and weak acid (also give examples)
Acid is a proton donor. Strong acids: * HCl, * H2SO4, * HNO3
Weak acids:
* CH3COOH
Define/explain the following
7) Strong and weak base (also give examples)
Bases is a proton acceptor.
Strong bases:
* NaOH,
* Ba(OH)2
Weak base:
*Cl-
Define/explain the following
8) State function
A state function is a property of a system that depends only on the current state of the system, i.e. the initial and final state of the system.
Define/explain the following
9) Pressure
Pressure = Force/Area; P=F/A
10) Lipophillic and lipophobic
- Lipophillic
- Capable of dissolving, of being dissolved in, or of absorbing lipids.
- Lipophobic:
- Detergent is solvated in water. Contrasted to lipophilic or nonpolar.
- Not soluble in lipids, or in non-polar solvents
11) Hypertonic, hypotonic and isotonic solutions
Hypertonic:
Hypotonic:
Isotonic solutions:
12) Emulsion
A mixture of two or more liquids that are normally immiscible (unmixable or unblendable). Emulsions are part of a more general class of two-phase systems of matter called colloids.
13) Thixotropy
A time-dependent shear thinning property.
Certain gels or fluids that are thick, or viscous, under static conditions will flow (become thin, less viscous) over time when shaken, agitated, sheared or otherwise stressed (time dependent viscosity).
They then take a fixed time to return to a more viscous state. In other words: some non-Newtonian pseudoplastic fluids show a
14) Osmotic pressure
The minimum pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane.
It is also defined as the measure of the tendency of a solution to take in water by osmosis.
15) Enthalpy change
At constant pressure, the enthalpy change equals the energy transferred from the environment through heating or work other than expansion work.
Categorization
1) Which one is a typical emulsifier in food? Gelatin, Casien, Cellulose, Lecithin
Lecithin
Categorization
2) Write the names of one typical surfactants!
Soap
Categorization
3) Write the names of three typical gelling agents!
Pectins, Xantan gum, Gelatin
Categorization
4) Write the names of two typical preservatives!
Benzoic acid, Propionic acid, Biphenyl
Categorization
5) Write the names of three typical organic food contaminates!
Thiomersal, Arsenic, Bisphenol A
Categorization
6) Write the names of three typical aroma agents!
Umami, Curculin, Glutamic acid
Categorization
7) Which one is a typical food colorant?
Aspartame, Riboflavin, Ethoxyquin
Riboflavin/Vitamin B2.
Aspartame=Sweetener, Ethoxyquin=Antioxidant
Categorization
8) Write the names of three typical antioxidants!
Ascorbic acid,
Tocopherols,
Ethoxyquin,
ROS
Categorization
9) Write the names of three typical mycotoxins!
Aflatoxins,
Ochratoxins,
Citrinin
Draw the structural formula
1) Pyridine
2) Isoprene
3) Indole
4) Any nucleoside
5) Imidazole (also number it)
6) Isoquinoline
7) Gonane
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