Questionnaire

Question 1

What is the mass of a protium ( hydrogen without a neutron) isotope.

Answer 1

Solution:

Mass of protium = mass of proton+mass of electron

Mass = 1.67x10–²⁷ + 9.11x10-³¹
Mass = 1.67*10-²⁷ kg

Question 2

What is 77°F in Kelvin units?

Answer 2

Solution:

(77°F - 32) x 5/9 + 273.15 = 298.15 K

Question 3

What is the value of the universal gas constant in cal/mol-K?

Answer 3

Solution:

R= 8.3145 J/mol·K x (1 cal/4.184 J)
R= 1.987 cal/mol·K

Question 4

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

Answer 4

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

Question 5

A liquid has a density of 59.1 lb/ft³. What is its density in SI units?

Answer 5

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

Question 6

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.

Answer 6

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%

Question 7

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

Answer 7

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

Question 8

Calculate the pH of a 0.20 M solution of HF (Ka = 3.4 x 10–⁴).

Answer 8

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

Question 9

What is the resulting expression if —log is applied to both sides of the equation?

Ka= [H+][A–]/ [HA]

Answer 9

Solution:
-logKa = -log( [H+][A–]/ [HA] )

pKa = pH - log([A–]/ [HA])

Question 10

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?

Answer 10

Solution:

E² = 2² + 1²

E= 2.23

Question 11

What is the pH of a solution that contains 0.0053 ± 0.0004 M hydronium ion?

Answer 11

Solution:

pH = -log(0.0053) ±1/ln10 x 0.0004/0.0053

pH = 2.28 ± 0.03

Question 12

What is the second derivative of the given function?

f(x) = sin x + cos x

Answer 12

Solution:

1st derivative: cos x - sin x
2nd derivative: -sin x - cos x

Question 13

What is the result of the differential of the equation, H= U + PV is taken?

Answer 13

Solution:

H = U + PV
dH = dU + PdV + VdP

Question 14

What is the (dV/dT)p of the modified van der Waals equation?

_
V = RT/P - a/RT + b

Answer 14

Solution:

(dV/dT)p = d/dT (RT/P) - d/dT (a/RT) + d/dT (b)

(dV/dT)p = R/P + a/T²

Question 15

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.

Answer 15

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

Question 16

What are examples of physical change?

Answer 16

-melting
-change of size/shape
-volume
-density
-crystal form

Question 17

What are examples of chemical change?

Answer 17

• change in color
• change in temperature
• change in odor
• burning
• digestion
• decomposition

Question 18

what is the % abundance of Cl-35 and Cl-37 if the average atomic mass of chlorine is 35.45 amu?

Answer 18

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%

Question 19

Who postulated the energy emission of an electron when it drops from higher to lower energy level?

Answer 19

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.

Question 20

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?

Answer 20

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

Question 21

He postulated that all matter is made up of small indestructible units called atoms.

Answer 21

Democritus

Question 22

He proposed the Atomic Theory which states;

1. Each element is made up of atoms.
2. Atoms of a given element are identical.
3. Compounds are formed when atoms combine with each other.
4. Chemical reactions involve reorganization of the atoms.

Answer 22

John Dalton

Question 23

He created the periodic table and discovered that the properties of elements were periodic functions of their atomic weights.

Answer 23

Dmitri Mendeleev

Question 24

He proposed the Theory of Electromagnetism and made the connection between light and electromagnetic waves.

Answer 24

James Clark Maxwell

Question 25

He proposed that electricity was made of discrete negative particles he called *electrons*.

Answer 25

**George Stoney**

Question 26

He made experiments with *cathode ray tubes* demonstrating that cathode rays have a negative charge.

Answer 26

**Sir William Crooke**

Question 27

He used *cathode ray tubes* to study canal rays which had electrical and magnetic properties opposite of an electron.

Answer 27

**Eugene Goldstein**

Question 28

He discovered that certain chemicals glowed when exposed to cathode rays. He named these **X-rays**.

Answer 28

**Wilhelm Roentgen**

Question 29

He discovered **radiation** by studying the effects of X-rays on photographic film.

Answer 29

**Henri Becquerel**

Question 30

He used cathode ray tubes to determine the *charge-to-mass ratio* of an electron.

Answer 30

**Sir Joseph John Thomson**

Question 31

He discovered*alpha*, *beta*, and *gamma* rays in radiation.

Answer 31

**Ernest Rutherford**

Question 32

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*.

Answer 32

**Marie and Pierre Curie**

Question 33

He proposed the idea of *quantization* to explain how a hot, glowing object emitted light.

Answer 33

**Max Planck**

Question 34

He discovered that there appeared to be more than one element at each position on the periodic table.

Answer 34

**Frederick Soddy**

Question 35

She coined the term *isotope*.

Answer 35

**Margaret Todd**

Question 36

He found that noble gases have stable electron configurations.

Answer 36

**Richard Abegg**

Question 37

He created the *Theory of Relativity* and hypothesized about the particle nature of light.

Answer 37

**Albert Einstein**

Question 38

He invented a device that could detect *alpha particles*.

Answer 38

**Hans Geiger**

Question 39

He determined the charge of an electron through his *oil drop experiment*.

Answer 39

**Robert Millikan**

Question 40

He performed the *alpha particle experiment* and established that the nucleus was very dense, very small and positively charged.

Answer 40

**Ernest Rutherford**

Question 41

He discovered that the number of protons in an element determines its atomic number.

Answer 41

**Henry Moseley**

Question 42

He developed the *Bohr atomic model*, with electrons traveling in orbits around the nucleus.

Answer 42

**Neils Bohr**

Question 43

He proposed that electrons have a wave-particle duality.

Answer 43

**Louis de Broglie**

Question 44

He developed the *Schrödinger equation* which describes how the quantum state of a system changes with time.

Answer 44

**Erwin Schrödinger**

Question 45

Any of two or more species of atoms or nuclei that have the *same number of neutrons*.

Answer 45

**Isotone**

Question 46

Atoms of different elements with *different atomic numbers* but have the *same mass number*.

Answer 46

**Isobar**

Question 47

The energy required to separate a nucleus into neutrons and protons.

Answer 47

**Nuclear binding energy**

Question 48

Nuclear binding energy

Answer 48

**E = ∆mc²**

Question 49

_________ determines if the nucleus will undergo *radioactive decay*.

Answer 49

**Nuclear stability**

Question 50

Guidelines in determining the stability of a nuclide.

Answer 50

1. **Unstable if**, it has **>84 protons**. 2. **Unstable if**, the neutron-to-proton ratio lies outside the stability belt. 3. **Stable** if there are **even** number of **nucleons**, **protons** are of higher priority. 4. Nuclides that have **magic numbers ( 2, 8, 20, 50, 82, 126)** are **more stable**.

Question 51

Types of Radioactive Decay

Answer 51

-Alpha Decay -Beta Decay -Gamma Emission -Positron Emission -Electron Capture

Question 52

If Z > 38, the type of decay is

Answer 52

**Alpha Decay**

Question 53

If Z = 1-20, and n/p ≥ 1, the type of decay is

Answer 53

**Beta decay**

Question 54

If Z=1-20, and n/p ≤1, the type of decay is

Answer 54

**Positron/ Electron Capture**

Question 55

In Beta decay, if Z= 21-40, n/p is______.

Answer 55

**≥1.25**

Question 56

In Beta decay, if n/p ≥1.5, Z=_____.

Answer 56

**41-82**

Question 57

In Positron/Electron Capture, if n/p≤1.25, then Z=_____.

Answer 57

**21-40**

Question 58

In Positron/ Electron Capture, if Z=41-82, then n/p ____.

Answer 58

**≤1.5**

Question 59

**Radioactive decay** is a __________which can be useful in determining the remaining amounts of a certain nuclide on a sample.

Answer 59

**first-order reaction**

Question 60

First-order reaction

Answer 60

**lnN/No = -kN**

Question 61

Half-life Equation

Answer 61

**ln2 = kt** **¹/²**

Question 62

Formula for Activity (a)

Answer 62

**A= kN**

Question 63

At which wavelength do gamma rays exist?

Answer 63

**10–¹² m to 10–¹¹ m** **1 pm to 10 pm**

Question 64

At which wavelength range can you find X-rays?

Answer 64

**10–¹¹ to 10–⁸ m** **10 pm to 10 nm**

Question 65

At which wavelength can you find NIR waves?

Answer 65

**10–⁶ to 10–⁵ m** **1 μm to 10μm**

Question 66

Where does visible light fall on the electromagnetic spectrum?

Answer 66

**400-800 nm**

Question 67

Light or ___________ has ___________ electric and magnetic fields in planes perpendicular to each other to the direction of propagation.

Answer 67

**-electromagnetic radiation** **-oscillating**

Question 68

Relationship of *wavelength* and *frequency*

Answer 68

**Inverse relationship** **λν=c**

Question 69

Light as a wave phenomenon

Answer 69

**E=hc/λ**

Question 70

Light as a stream of photons

Answer 70

**E=hv**

Question 71

The phenomenon in which electrons are emitted from the surface of a metal when light strikes it.

Answer 71

**Photoelectric Effect**

Question 72

Energy of the incident light

Answer 72

**Einc=φ+KE = hvo + 1/2mv²**

Question 73

The *atomic spectrum* of hydrogen was a result of the___________.

Answer 73

**excitation of the atoms and subsequent relaxation, releasing energy by emitting light of various wavelengths.**

Question 74

Rydberg Equation

Answer 74

**1/λ = Rh (1/n²1 - 1/n²2)**

Question 75

Rydberg only works with atoms with______.

Answer 75

**1e-**

Question 76

Lyman series moves from n=5,4,3,2 to

Answer 76

**n=1**

Question 77

Balmer series moves from n= 5,4,3 to

Answer 77

**n=2**

Question 78

Paschen series moves from

Answer 78

**n=5,4 to n=3**

Question 79

Bracket series moves from

Answer 79

**n=5 to n=4**

Question 80

Pfund series moves from

Answer 80

Higher energy level to n=5

Question 81

Bohr derived the equation to compute the energy levels available to the electron in the hydrogen atom.

Answer 81

**E=-2.178x10–¹⁸/ n² J = –13.6/n² eV**

Question 82

Quantum mechanics was developed by _________ to account for the wave-particle duality of the electron.

Answer 82

**De Broglie, Heisenberg, and Schrödinger**

Question 83

De Broglie Equation

Answer 83

**λ= h/mv**

Question 84

-Main energy levels or shells -distance of electrons from nucleus

Answer 84

**Principal Quantum Number (n)**

Question 85

- energy subshells - shapes of the orbitals

Answer 85

**Azimuthal Magnetic Number (ι)**

Question 86

- number of orbitals in subshells - possible orientation of orbitals in space

Answer 86

**mι**

Question 87

- movement of the electron around its own axis - can be clockwise or counterclockwise

Answer 87

**Spin Quantum Number (ms)**

Question 88

Allowed values for *principal (n)*

Answer 88

**n=1,2,3**

Question 89

Allowed values for *azimuthal (ι)*

Answer 89

**ι=0 to n-1**

Question 90

Allowed values for *magnetic quantum number*

Answer 90

**mι = -ι to ι**

Question 91

Allowed values for *spin quantum number*

Answer 91

**ms = -1/2,1/2**

Question 92

Maximum number of orbitals in a subshell

Answer 92

**2ι + 1**

Question 93

Maximum number of orbitals in a shell

Answer 93

n²

Question 94

Maximum number of electrons in a subshell

Answer 94

**2(2ι + 1)**

Question 95

Μaximum number of electrons in a shell

Answer 95

**2n²**

Question 96

angular nodes

Answer 96

L

Question 97

Radial nodes

Answer 97

n-1-L

Question 98

**Aufbau Principle**

Answer 98

Orbitals are filled with electrons in increasing energy

Question 99

**Madelung rule or Klechkowsky's Rule**

Answer 99

Orbitals with lower *n+1* value are filled first

Question 100

**Hund's Rule of Maximum Multiplicity**

Answer 100

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.**

Question 101

**Pauli's Exclusion Principle**

Answer 101

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.

Question 102

The lowest energy arrangement of electrons in the orbitals of the atom.

Answer 102

**ground state electron configuration**

Question 103

Comprises of allowed arrangements other than the ground state.

Answer 103

**Excited State**

Question 104

Exceptions to the Aufbau Principle

Answer 104

**Transition metals, lanthanides and actinides** Ex: **Cr, Mo, Gd, Cm, Cu, Pd, Ag, Au**

Question 105

As the atomic number Z increases, the electrons are___________. However, the changes are irregular because of ______ of outer electrons by inner electrons.

Answer 105

**-drawn toward the nucleus and the orbital energies become more negative.** **-shielding**

Question 106

The measure of nuclear attraction for an electron.

Answer 106

**Effective nuclear charge, Zeff** **Zeff = Z-S**