Exam 2 Flashcards
Density
(ρ = m/v) -> kg/m^3 , g/mL , g/cm^3
Reference liquid
Density of water at 4°C and 1 atm is 1000 kg/m3, or 1 g/cm3
Specific gravity
dimensionless constant = ρ/ρwater
If substance has specific gravity > 1
sink
If substance has specific gravity < 1
float
% of the object that will be submerged =
specific gravity x 100
buoyant force
When objects float in a liquid, that fluid exerts an upward force on the object
Floating object => magnitude of buoyant force
Fb = ρliquidVliquidg > weight of object
Archimedes principle
buoyant force is directly proportional to the volume of the liquid
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pH equation
pH = −log [H+]
H+ concentration of 10−4 M will have a pH of 4
pOH equation
pOH = −log [OH-]
○ OH− concentration of 10−9 M will have a pOH of 9
Shortcut calculation for pH
p(N × 10?M) = (M?1).(10−N) = H+ concentration of 4 × 10−8 will have a pH = (8−1).(10−4) = 7.6
pKw
pH + pOH = pKw = 14
autoionization constant of water (Kw = [H3O+][OH−] = 1 × 10−14 at 25°C)
Viscosity
resistance to flow = resistance to deformation by shear stress
For MCAT viscosity is negligible and fluid are incompressible (fixed volume)
Laminar flow
flowing fluid is composed of parallel layers that may be moving at different velocities = smooth well-behaved flow that is easy to model
Turbulent flow
the smooth regulated layer of laminar flow breakdown
Poiseuille’s Law
describes laminar flow of incompressible fluids through a long cylindrical tube
Poiseuille’s law equation
Q = ΔPπr^4 / 8Lη ; ΔP = 8LηQ/πr^4
○ the flow rate (Q)
§ Flow rate (Q) is directly proportional to r^4
○ the pressure drop between both ends of the tube (ΔP)
○ the radius of the tube (r)
○ the length of the tube (L)
○ and the viscosity (η)
Bernoulli’s Equation
conservation of energy for fluids
- P1 + ½ ρv1^2 + ρgh1 = P2 + ½ ρv2^2 + ρgh2
- v = velocity; ½ ρv2 = KE of the fluid
- h = height; ρgh = PE of the fluid
§ When height is constant => horizontal pipe system => increase in velocity corresponds to a decrease in pressure. Vice verse
- P = pressure
Continuity Equation
(v1A1 = v2A2)
- Within a closed system, the flow rate of a liquid is constant -> velocity of the fluid (v) is inversely proportional to the cross-sectional area that it is flowing through
Work
energy transfer (J)
- 1J = 1N*m or 1 kg*m^2/s^2 - Work done when a force is applied to an object for a certain distance: W = |F|*d*cos(θ) -> vector - Work = area under curve of F (y-axis) and d (x-axis) - Work = pressure * change in volume = PΔV
Net work performed on or by an object
change of its kinetic energy: Wnet = KE final - KE initial
Wavelength from longest to shortest
radio -> microwaves -> IR -> Visible -> UV -> X-rays -> Gamma rays