Questionnaire Flashcards
What is the mass of a protium ( hydrogen without a neutron) isotope.
Solution:
Mass of protium = mass of proton+mass of electron
Mass = 1.67x10–²⁷ + 9.11x10-³¹
Mass = 1.67*10-²⁷ kg
What is 77°F in Kelvin units?
Solution:
(77°F - 32) x 5/9 + 273.15 = 298.15 K
What is the value of the universal gas constant in cal/mol-K?
Solution:
R= 8.3145 J/mol·K x (1 cal/4.184 J)
R= 1.987 cal/mol·K
What is the temperature of one mol of van der Waals gas at 49.6 atm at 0.536 L?
P= (nRT)/(V-nb) - n²a/v²
a= 3.61 L²·atm·mol²
b=0.0428L/mol
R=0.0821 L·atm/mol·K
Solution:
49.6 atm=[(1mol x 0.0821 L·atm/mol·K)/(0.536 L - (1 mol x 0.0428 L/mol)) ] - [(1 mol)² x 3.61 L²·atm·mol²)/0.536 L²]
49.6 atm=0.16646 atm/K - 12.56544 atm
49.6 atm - 12.56544 atm= 0.16646 atm/K
T= 373.45 K
A liquid has a density of 59.1 lb/ft³. What is its density in SI units?
Solution:
59.1 lb/ft³ x 0.45359 kg/lb x 1000 g/kg x 1 ft³/(0.3048 m)³
= 946.7 kg/m³
Nitrogen-15 (15.000108 amu) and Nitrogen-14 (14.003074 amu) comprises the majority of all the naturally-occurring isotopes. What is the fractional relative abundance of N-14? Let X be the relative abundance of N-14 and M be the atomic masses of the isotopes.
Solution:
M(N-14)X + M(N-15)(1-X) = 14.01
14.003074X + 15.000108(1-X) = 14.01
14.003074X - 15.000108X + 15.000108 - 14.01 = 0
-0.997X + 0.990 = 0
-0.997X = -0.990
X=0.993%
Calculate the mass of NaCl using the equations below obtained from a certain gravimetric analysis.
M(KCl) + M(NaCl) = 2.3 g
0.61M(KCl) + 0.48M(NaCl) = 1.27 g
Solution:
=> from eq.1,
M(KCl) = 2.3 - M(NaCl)
=> from eq.2,
0.61 (2.3 - M(NaCl)) + 0.48M(NaCl) = 1.27 g
1.403 g - 0.61M(NaCl) + 0.48M(NaCl)= 1.27 g
1.403 g - 1.27 g = 0.13M(NaCl))
M(NaCl) = 1.023 g
Calculate the pH of a 0.20 M solution of HF (Ka = 3.4 x 10–⁴).
Solution:
Ka = [H+]²/0.20- [H+]
3.4 x 10–⁴= x²/0.20 - x
3.4 x 10–⁴ (0.20 - x) = x²
6.85 x 10–⁵ - 3.4 x 10–⁴x= x²
x² + 3.4 x 10–⁴x - 6.85 x 10–⁵ = 0
X = 0.008
pH = -log(X)
pH = 2.09
What is the resulting expression if —log is applied to both sides of the equation?
Ka= [H+][A–]/ [HA]
Solution:
-logKa = -log( [H+][A–]/ [HA] )
pKa = pH - log([A–]/ [HA])
A beaker holds a 153 (±2) mL of liquid, then a 62 (±1) mL potion was removed. What is the uncertainty of the remaining liquid volume?
Solution:
E² = 2² + 1²
E= 2.23
What is the pH of a solution that contains 0.0053 ± 0.0004 M hydronium ion?
Solution:
pH = -log(0.0053) ±1/ln10 x 0.0004/0.0053
pH = 2.28 ± 0.03
What is the second derivative of the given function?
f(x) = sin x + cos x
Solution:
1st derivative: cos x - sin x
2nd derivative: -sin x - cos x
What is the result of the differential of the equation, H= U + PV is taken?
Solution:
H = U + PV
dH = dU + PdV + VdP
What is the (dV/dT)p of the modified van der Waals equation?
_
V = RT/P - a/RT + b
Solution:
(dV/dT)p = d/dT (RT/P) - d/dT (a/RT) + d/dT (b)
(dV/dT)p = R/P + a/T²
The work associated with isothermal reversible expansion or compression of gas is given by the equation below. Calculate the work associated if 52 mol gas is compressed from 30 to 10 L at 260 K.
Solution:
v2
W = -∫ nRT/V dV
** v1**
W = -nRT ∫1/v dV
W = -nRT (ln v)|¹⁰
³⁰
W = - 52 mol · 8.314 J/ mol·K ·260K (ln30 - ln10)
W = 123,489 J
What are examples of physical change?
-melting
-change of size/shape
-volume
-density
-crystal form
What are examples of chemical change?
- change in color
- change in temperature
- change in odor
- burning
- digestion
- decomposition
what is the % abundance of Cl-35 and Cl-37 if the average atomic mass of chlorine is 35.45 amu?
Solution:
Let x = % abundance of Cl-35
Let 1-x = % abundance of Cl-37
35.45 = 35(x) + 37(1-x)
35.45 = 35x - 37x + 37
35.45 - 37 = 35x -37x
-1.55 = -2x
x = 0.775 or 77.5%
1-x = 0.225 or 22.5%
Who postulated the energy emission of an electron when it drops from higher to lower energy level?
Neils Bohr
The Bohr model postulates that electrons orbit the nucleus at fixed energy levels. Orbits further from the nucleus exist at higher energy levels. When electrons return to a lower energy level, they emit energy in the form of light.
Electrons are ejected when a certain metal is irradiated with radiation with a frequency of 5.5x10¹⁴/s. If the work function of the metal is 2.9x10–¹⁹ J, what is the kinetic energy of each ejected electrons?
Solution:
Planck’s constant = 6.626 x 10–³⁴ J·s
KE= (5.5 x 10¹⁴/s) · (6.626 x 10–³⁴ J·s) - (2.9 x 10–¹⁹ J)
KE = 7.443 x 10–²⁰ J
He postulated that all matter is made up of small indestructible units called atoms.
Democritus
He proposed the Atomic Theory which states;
- Each element is made up of atoms.
- Atoms of a given element are identical.
- Compounds are formed when atoms combine with each other.
- Chemical reactions involve reorganization of the atoms.
John Dalton
He created the periodic table and discovered that the properties of elements were periodic functions of their atomic weights.
Dmitri Mendeleev
He proposed the Theory of Electromagnetism and made the connection between light and electromagnetic waves.
James Clark Maxwell
He proposed that electricity was made of discrete negative particles he called electrons.
George Stoney
He made experiments with cathode ray tubes demonstrating that cathode rays have a negative charge.
Sir William Crooke
He used cathode ray tubes to study canal rays which had electrical and magnetic properties opposite of an electron.
Eugene Goldstein
He discovered that certain chemicals glowed when exposed to cathode rays. He named these X-rays.
Wilhelm Roentgen
He discovered radiation by studying the effects of X-rays on photographic film.
Henri Becquerel
He used cathode ray tubes to determine the charge-to-mass ratio of an electron.
Sir Joseph John Thomson
He discoveredalpha, beta, and gamma rays in radiation.
Ernest Rutherford
They theorized that radioactive particles cause atoms to break down releasing radiation that takes the form of energy and subatomic particles. They discovered the radioactive elements, polonium and radium.
Marie and Pierre Curie
He proposed the idea of quantization to explain how a hot, glowing object emitted light.
Max Planck
He discovered that there appeared to be more than one element at each position on the periodic table.
Frederick Soddy
She coined the term isotope.
Margaret Todd
He found that noble gases have stable electron configurations.
Richard Abegg
He created the Theory of Relativity and hypothesized about the particle nature of light.
Albert Einstein
He invented a device that could detect alpha particles.
Hans Geiger
He determined the charge of an electron through his oil drop experiment.
Robert Millikan
He performed the alpha particle experiment and established that the nucleus was very dense, very small and positively charged.
Ernest Rutherford
He discovered that the number of protons in an element determines its atomic number.
Henry Moseley
He developed the Bohr atomic model, with electrons traveling in orbits around the nucleus.
Neils Bohr
He proposed that electrons have a wave-particle duality.
Louis de Broglie
He developed the Schrödinger equation which describes how the quantum state of a system changes with time.
Erwin Schrödinger
Any of two or more species of atoms or nuclei that have the same number of neutrons.
Isotone
Atoms of different elements with different atomic numbers but have the same mass number.
Isobar
The energy required to separate a nucleus into neutrons and protons.
Nuclear binding energy
Nuclear binding energy
E = ∆mc²
_________ determines if the nucleus will undergo radioactive decay.
Nuclear stability
Guidelines in determining the stability of a nuclide.
- Unstable if, it has >84 protons.
- Unstable if, the neutron-to-proton ratio lies outside the stability belt.
- Stable if there are even number of nucleons, protons are of higher priority.
- Nuclides that have magic numbers ( 2, 8, 20, 50, 82, 126) are more stable.
Types of Radioactive Decay
-Alpha Decay
-Beta Decay
-Gamma Emission
-Positron Emission
-Electron Capture
If Z > 38, the type of decay is
Alpha Decay
If Z = 1-20, and n/p ≥ 1, the type of decay is
Beta decay
If Z=1-20, and n/p ≤1, the type of decay is
Positron/ Electron Capture
In Beta decay, if Z= 21-40, n/p is______.
≥1.25
In Beta decay, if n/p ≥1.5, Z=_____.
41-82
In Positron/Electron Capture, if n/p≤1.25, then Z=_____.
21-40
In Positron/ Electron Capture, if Z=41-82, then n/p ____.
≤1.5
Radioactive decay is a __________which can be useful in determining the remaining amounts of a certain nuclide on a sample.
first-order reaction
First-order reaction
lnN/No = -kN
Half-life Equation
ln2 = kt
¹/²
Formula for Activity (a)
A= kN
At which wavelength do gamma rays exist?
10–¹² m to 10–¹¹ m
1 pm to 10 pm
At which wavelength range can you find X-rays?
10–¹¹ to 10–⁸ m
10 pm to 10 nm
At which wavelength can you find NIR waves?
10–⁶ to 10–⁵ m
1 μm to 10μm
Where does visible light fall on the electromagnetic spectrum?
400-800 nm
Light or ___________ has ___________ electric and magnetic fields in planes perpendicular to each other to the direction of propagation.
-electromagnetic radiation
-oscillating
Relationship of wavelength and frequency
Inverse relationship
λν=c
Light as a wave phenomenon
E=hc/λ
Light as a stream of photons
E=hv
The phenomenon in which electrons are emitted from the surface of a metal when light strikes it.
Photoelectric Effect
Energy of the incident light
Einc=φ+KE = hvo + 1/2mv²
The atomic spectrum of hydrogen was a result of the___________.
excitation of the atoms and subsequent relaxation, releasing energy by emitting light of various wavelengths.
Rydberg Equation
1/λ = Rh (1/n²1 - 1/n²2)
Rydberg only works with atoms with______.
1e-
Lyman series moves from n=5,4,3,2 to
n=1
Balmer series moves from n= 5,4,3 to
n=2
Paschen series moves from
n=5,4 to n=3
Bracket series moves from
n=5 to n=4
Pfund series moves from
Higher energy level to n=5
Bohr derived the equation to compute the energy levels available to the electron in the hydrogen atom.
E=-2.178x10–¹⁸/ n² J = –13.6/n² eV
Quantum mechanics was developed by _________ to account for the wave-particle duality of the electron.
De Broglie, Heisenberg, and Schrödinger
De Broglie Equation
λ= h/mv
-Main energy levels or shells
-distance of electrons from nucleus
Principal Quantum Number (n)
- energy subshells
- shapes of the orbitals
Azimuthal Magnetic Number (ι)
- number of orbitals in subshells
- possible orientation of orbitals in space
mι
- movement of the electron around its own axis
- can be clockwise or counterclockwise
Spin Quantum Number (ms)
Allowed values for principal (n)
n=1,2,3
Allowed values for azimuthal (ι)
ι=0 to n-1
Allowed values for magnetic quantum number
mι = -ι to ι
Allowed values for spin quantum number
ms = -1/2,1/2
Maximum number of orbitals in a subshell
2ι + 1
Maximum number of orbitals in a shell
n²
Maximum number of electrons in a subshell
2(2ι + 1)
Μaximum number of electrons in a shell
2n²
angular nodes
L
Radial nodes
n-1-L
Aufbau Principle
Orbitals are filled with electrons in increasing energy
Madelung rule or Klechkowsky’s Rule
Orbitals with lower n+1 value are filled first
Hund’s Rule of Maximum Multiplicity
The most stable arrangement of electrons in subshells is the one with the most number of parallel spins.
Before the double occupation of any orbital, every orbital in the sub level is singly occupied.
Pauli’s Exclusion Principle
An orbital must contain a maximum of two electrons with opposite spins; hence no two electrons can have the same set of four quantum numbers.
The lowest energy arrangement of electrons in the orbitals of the atom.
ground state electron configuration
Comprises of allowed arrangements other than the ground state.
Excited State
Exceptions to the Aufbau Principle
Transition metals, lanthanides and actinides
Ex: Cr, Mo, Gd, Cm, Cu, Pd, Ag, Au
As the atomic number Z increases, the electrons are___________. However, the changes are irregular because of ______ of outer electrons by inner electrons.
-drawn toward the nucleus and the orbital energies become more negative.
-shielding
The measure of nuclear attraction for an electron.
Effective nuclear charge, Zeff
Zeff = Z-S
