Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
157. Define the frictional force (F) acting on a molecule with
velocity v in an aqueous environment? |
F=-f·v, where f is the form factor.
|
|
|
158. What is the relationship between the absolute
temperature (T) and the average kinetic energy of a Minimum Requirement Questions (2005/06) 8 molecule (Ekin) in a system containing monatomic gas in thermal equilibrium? |
Ekin = 3/2 kT
where k is the Boltzmann constant. |
|
|
159. What is diffusion?
|
Net flow of material propelled by Brownian motion due to
a gradient of the chemical potential. |
|
|
160. What is the physical meaning of the diffusion constant?
|
The diffusion constant (D) is the amount of material
transported through unit surface area in unit time at a unit concentration gradient. |
|
|
161. What is the unit of diffusion constant?
|
[D] = m2/s
|
|
|
162. Give the average squared displacement and averate
squared rotation of a particle with diffusion constant D and rotational diffusion constant Drot, respectively! |
x^2 = Dt Θ^2 = 2Drot t
where t is time, and x2 and Θ2 is the average squared displacement and rotation, respectively. |
|
|
163. Write Fick's first law and interpret the constants and
physical quntities! |
dm/dt = -DA(dc/dx)
dm quantity of material is transported through surface A in time dt by a concentration gradient dc/dx, D is the diffusion constant |
|
|
164. How does the diffusion constant (D) depend on
temperature (T) and the radius of the molecule (r) ? |
D~T/r
|
|
|
165. Write down the equation describing the relationship
between the diffusion constant (D) and the form factor (f)! |
D=kT/
where k is the Boltzmann constant and T is the absolute temperature. |
|
|
166. Which parameters tend toward spatial equilibration
during a diffusion process? |
The chemical potentials of the components.
|
|
|
167. What is pH?
|
The negative logarithm with base 10 of the molar
concentration of hydrogen ions: pH=-lg[H+] |
|
|
168. What is the permeability constant?
|
The permeability constant is the amount of material
transported through the membrane per unit surface in unit time due to unit concentration difference. |
|
|
169. Give the equation describing the amount of material
transported through a membrane due to a concentration gradient? |
dm = −k ⋅ A⋅Δc ⋅ dt
where dm is the amount of material transported through membrane surface A during time dt as an effect of Δc concentration difference, k is the membrane permeability |
|
|
170. Write down van't Hoff's law!
|
Posm = RTc, where
Posm - osmotic pressure, R is theuniversal gas constant, T is absolute temperature, c is the molar concentration of the material in solution. |
|
|
171. What is osmosis?
|
Flow of the solvent to a concentrated solution from the
more dilute one, if the two compartments are separated by a semipermeable membrane. This material flow decreases the concentration gradient between the two solutions. |
|
|
172. What is osmotic pressure?
|
It is the pressure generated by the flow of the solvent
molecules through a semipermeable membrane which is able to compensate the solvent flow. |
|
|
173. What is the average speed at which the heart pumps the
blood into the aorta? |
20-40 cm/s
|
|
|
174. What is the average amount of blood pumped out of the
heart during a single contraction? |
70-90 mL
|
|
|
175. What components does the work of the heart consist of?
|
Volumetric and kinetic work.
|
|
|
176. Describe in words the law of Bernoulli!
|
The sum of the statical, dynamic and gravitational
(hydrostatic) pressures is constant. |
|
|
177. What kind of chemical bonds does electromagnetic
waves of a microwave oven disrupt? |
The hydrogen bonds of water.
|
|
|
178. Why does a microwave oven boils water?
|
Because water is able to absorb the microwaves in the
oven since the energy of the hydrogen bonds between water molecules is approximately the same as the energy of a microwave photon. |
|
|
179. What is the relationship between the number of bacteria
and time under optimal conditions? |
t
N=No2^T N is the number of bacteria at time t, N0 is the initial number of bacteria at t=0, T is the generation time. |
