Practical Exam Flashcards

1
Q

Density def:

A

Property indicating how much substance is in unit of volume

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2
Q

Density formula:

A

p = m/V (mass, volume) kg/m^3

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3
Q

Density SI

A

Kg/m^3

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4
Q

Density depends on

A

Temperature, mass, crystalline form
If T goes up p goes down, exception for water

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5
Q

Density of heterogenous

A

p(r) = dm(r)/dV(r)

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6
Q

Relative density of liquid

A

p = p(liquid)/p(solution)

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7
Q

Measuring density of liquids (material)

A
  • scale
  • pipette
  • pycnometer
  • distilled water
  • solution sample
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8
Q

Density of liquids procedure

A
  • weigh empty pycnometer
  • fill with water and weigh
  • fill with sample and weigh
  • find pycnometer volume
  • calculate density
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9
Q

Density of solids material

A
  • scale
  • pycnometer
  • solid
  • distilled water
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10
Q

Density of solids procedure

A
  • weight solid in air
  • fill pycnometer with water znd weigh
  • fill water pycnometer with solids and weigh
  • calculate
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11
Q

What is measurement of density of solids by immersion technique based on

A

Archimeds law: a solid is lighter in water than in air

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12
Q

Buoyant force formula

A

Fb = mH2O x g

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13
Q

Density of solids by immersion material

A
  • scale
  • beaker
  • water
  • sample
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14
Q

Density of solids by immersion procedure

A
  • weight sample in air
  • weight sample immersed in water
  • calculate
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15
Q

Order of magnitude

A

Approximating answer

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16
Q

Fluids definition

A

Substance that can flow, given by velocity of particles per time

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17
Q

Flaw rate through pipe

A

Quantity of fluid passing through cross section of pipe in unite time

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18
Q

Volumetric flow rate

A

Qv = delta V /delta t
SI = m^3/s

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19
Q

Mass flow rate

A

Qm = delta m / delta t
SI: kg/s

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20
Q

Relation btw mass flow rate and voluletric flow rate

A

Qm = p x Qv

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21
Q

Laminar or streamline flow

A
  • liquid flows smooth
  • parallel layers to direction of flow
  • low energy consume
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22
Q

Turbulent flow

A
  • molecular flow irregulzr
  • generate currents
  • high energy consumption for flow rate
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23
Q

Viscosity def

A

Resistance to flow

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24
Q

Viscosity determinced by

A
  • internal frictions btw layers of fluid
  • determined by size of molecules
  • more temperature leads to lower viscosity
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25
Q

Motion of liquid newtonian law

A

F = nxAx(delta Vx / delta y)

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26
Q

Constant of proportionality n

A
  • represents dynamic viscosity of liquid
  • SI: (N x s)/m^2 = Pa x s
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27
Q

Newtonian fluids

A

If dynamic viscosity of fluid depends on velocity, liquids are non newtonian like blood

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28
Q

Flow rate through cylindrr formula

A

Qv = delta (p . pi . r^4)/(8.n.L)

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29
Q

What does the nature of flow depend on

A

Reynold’s number
Re = (p.v.r).n
Re < 2000 -> laminer
Re > 4000 -> turbulent
Also there is in between

30
Q

Buoyancy force

A

Weight of didplaced Volume of liquid
Fb = (4.pi.r^2)/3 .p.g

31
Q

Instrument for viscosity

A

Ostwald viscosmeter
n(solution) = n(h20).(ps/ph2o).(ts/th2o)

32
Q

Hoppler viscometer

A
  • fill with water
  • put solide in tube
  • wait for it to go from line 1 to line 2 and record time
  • do the same with other liquids
  • calculate
33
Q

What keeps molecules packed together

A

Intermoleculzr interactions, cohesive forces

34
Q

What is internal pressure

A

The molecules at surface in contact with air are attracted inwars creating pressure

35
Q

Potential energy of surface layer

A

Ep = surface tension x A

36
Q

Surface tension

A

Represents the surface energy per unit area
SI: J/m^2 = N/m

37
Q

Tensioactive substance

A

Substance that are absorbed in surface layer and reduce surface tension

38
Q

Stalagmometer, drop counting method

A
  • fill stalafmometer with water, count drops, use a solution with diff concentration after, determine surface tension for solution
39
Q

Enthalpy formula

A

H = U + pV
U = internl energy
P = pressure
V = volume

40
Q

Enthalpy variation formula

A

delta H = delta U + p x delta V

41
Q

Enthalpy variation def

A

Heat released or absorbed by the system in isobaric process

42
Q

Why use calorimeter

A

So the energy will be conserved
deltaQ…

43
Q

Determination of dissolution enthalpy procedure

A

Fill calorimeter with some water, measure temperature, put kcl in tube and put tube in calorimeter, meadure temp, put tube contents in calorimeter, measure temp

44
Q

Determination of enthalpy formula

A

delta Q = delta H = -(m.c+C).delta T

45
Q

Heat definition

A

Form of energy describing energetic exchange between a thermodynamic system and surrounding environment

46
Q

Heat capacity

A

Amount of heat necessary to change temperature of substance by 1°C
C = deltaQ/deltaT

47
Q

Specific heat capacity

A

Quantity of heat necessary for unit mass of substance to change by 1°C
c = 1/m . deltaQ/deltaT

48
Q

Molar heat capacity

A

Quantity of heat necessary for mole of substance to change temperature by 1 degree
Cmolar = 1/n . deltaQ/deltaT

delta Q is heat exchanges with surrounding
Delta T is température variation

49
Q

Heat in SI

A

Joules J

50
Q

Calorie def

A

Amount of heat required to rise teperzture of one gram of water

51
Q

C (Heat capacity) SI

A

C = deltaQ/deltaT
1.J/K

52
Q

c (specific heat) SI

A

c = 1/m. deltaQ/deltaT
J/(kg.K)

53
Q

Cmolar (molar heat) SI

A

Cmolar = deltaQ/(n.deltaT)
J/mole.K

54
Q

Latent heat

A

Specific heat at phase transition, heat exchange with no temperature change
J/kg

55
Q

Determination of specific heat of solids

A
  • weight metals, fill water in cup and heat to 100 degrees with metals inside, put water in calorimeter and record temp, put metal in calorimeter and record temperature when equilibrium, use formulas
56
Q

Refractive index

A

Ratio between speed of light in vacuum and in material
n = c/v

Shows how much the speed of light is reduced when passing through optical transparent

57
Q

Reflection of light

A

Partial or total return of light

58
Q

Refraction of light

A

Abrupt change in direction of propagation as it passes from one optical medium to another

59
Q

Snell’s law

A

Sin i /sin r =n2/n1 =n21
n21 = relative reftractive index

60
Q

Optical lenses

A

Refracting devices

61
Q

Focal point of lens

A

Point where parallel rays incident upon the lens converge

62
Q

How many focal points does lens have

A

2, object and image

63
Q

Convergence power

A

Reciprocal of focal length, C=1/f
SI: diopter = 1m^-1

64
Q

Magnification of a lens

A

B =y2/y1

65
Q

Optical aberration

A

Distortion of optical images, caused by shape of lens and wave of light

66
Q

Types of aberration

A

Spherical,coma,chromatic,distortion

67
Q

Focal distance

A

1/x2-1/x1=1/f

68
Q

Optical microscope

A

Optical instrument, objective,eyepiece,condenser

69
Q

Magnification

A

Ratio between tangent of angle under which one can see image thru instrument and tangent of zngle once can see when looked at with naked eye
G = tg a’/tg a

70
Q

Resolution

A

Shortest distance between two points of specimen
d = (0,61 . lambda)/NA
NA = numerical aparture