Chemmistry

Question 1

What is the typical volume composition of dry air?

Answer 1

~78% N₂, 21% O₂, ~1% Ar

Question 2

What determines the spontaneity of a chemical reaction?

Answer 2

The sign of ΔG (Gibbs Free Energy)

Question 3

What happens at the anode in a Daniell (Zn–Cu) cell?

Answer 3

Zn is oxidized, losing mass (Cu²⁺ is reduced at the cathode)

Question 4

What does a freezing point depression of 1°C indicate?

Answer 4

The solution’s freezing point is 1°C lower; first ice crystal is pure ice

Question 5

What is the molecular formula of ethylbenzene?

Answer 5

C₈H₁₀

Question 6

How do you relate coulombs to moles of metal in electrolysis?

Answer 6

1 Faraday = 96,485 C deposits 1 equivalent of metal

Question 7

Which property does NOT belong to ionic solids?

Answer 7

Good electrical conductivity in the solid state

Question 8

What is an amide and its structure?

Answer 8

R–C(=O)–NR₂ (a carbonyl bonded to an NR₂ group)

Question 9

What type of hydrocarbon is ethylene?

Answer 9

An alkene (C₂H₄)

Question 10

What are diamond and graphite with respect to carbon?

Answer 10

They are allotropes of carbon

Question 11

How does the magnetic quantum number mₗ range for a given n?

Answer 11

From −l to +l (e.g., if n=6, l can go up to 5, so mₗ = −5…+5)

Question 12

How to convert atm to mmHg?

Answer 12

Multiply atm by 760 (1 atm = 760 mmHg)

Question 13

What is the van’t Hoff coefficient formula?

Answer 13

i = 1 + α (z − 1)

If a fraction α of the solute dissociates into
z ions

Question 14

What is the ionization constant (Kb) for ammonia in water?

Answer 14

Kb ≈ 1.8×10⁻⁵

Question 15

How many moles of H₂O in 1 L of water?

Answer 15

~55.5 mol (at ~18 g/mol)

Question 16

If K &laquo_space;1 (like 10⁻⁴), which side is favored at equilibrium?

Answer 16

The reactants

Question 17

When NH₃ becomes NH₄⁺, how is it behaving?

Answer 17

As a Brønsted–Lowry base (accepting a proton)

Question 18

Which types of elements form an ionic bond?

Answer 18

A metal (low EN) with a nonmetal (high EN)

Question 19

Why can the mass of Ca vary?

Answer 19

Different isotopes exist; periodic table gives an average

Question 20

What is a homogeneous mixture?

Answer 20

A mixture with uniform composition (e.g., metal alloys)

Question 21

CₙH₂ₙ represents which class of hydrocarbons (open‐chain)?

Answer 21

Alkenes

Question 22

Is sublimation (solid→gas) endo‐ or exothermic?

Answer 22

Endothermic

Question 23

How do you find average molar mass of a gas mixture?

Answer 23

Weighted by mole or volume fraction times each gas’s molar mass

Question 24

Which particle was discovered first?

Answer 24

The electron

Question 25

Name a common metalloid (semimetal).

Answer 25

Antimony (Sb), or Silicon, etc.

Question 26

What does “12” in carbon‐12 represent?

Answer 26

The mass number (p + n = 12)

Question 27

What is the triple point temperature of CO₂?

Answer 27

~−56.6 °C

Question 28

Which molecule violates the octet rule?

Answer 28

PCl₅ (central P has 10 electrons)

Question 29

On what does the average molar mass of air depend?

Answer 29

Humidity (water vapor) and temperature

Question 30

How do you identify metals vs. nonmetals in the periodic table?

Answer 30

Metals on the left/center, nonmetals on right, metalloids near “staircase”

Question 31

Which subatomic particle was discovered first?

Answer 31

The electron

Question 32

Formula for hydrogen sulfide?

Answer 32

H₂S

Question 33

What are constitutional (structural) isomers?

Answer 33

Same molecular formula, different connectivity of atoms

Question 34

Is freezing of water exothermic or endothermic?

Answer 34

Exothermic (it releases heat)

Question 35

What is the formula of bromic acid?

Answer 35

HBrO₃

Question 36

How to convert grams of Be to moles?

Answer 36

mass ÷ (9 g/mol). E.g., 18 g = 2 mol

Question 37

Which isomer of 2‐butene has a nonzero dipole moment?

Answer 37

The cis isomer

Question 38

How many molecules in n moles?

Answer 38

n × Avogadro’s number (6.022×10²³)

Question 39

What is the formula of ethylbenzene?

Answer 39

C₆H₅–CH₂CH₃ (C₈H₁₀)

Question 40

Is bond formation spontaneous?

Answer 40

Generally yes (exothermic, lowers energy)

Question 41

Are there multiple types of intermolecular forces?

Answer 41

Yes: London forces, dipole‐dipole, H‐bonding, etc.

Question 42

Which metal is more easily reduced: Ag or Cu?

Answer 42

Silver (Ag) has the higher reduction potential

Question 43

Which oxide forms sulfuric acid in water?

Answer 43

SO₃ + H₂O → H₂SO₄

Question 44

Which period‐2 element has the highest first I.E.?

Answer 44

Fluorine (F)

Question 45

What is solid→gas phase change called?

Answer 45

Sublimation

Question 46

Name H₂SO₃ / Na₂SO₄.

Answer 46

Sulfurous acid / Sodium sulfate

Question 47

How many moles of S to form 64 g SO₂?

Answer 47

1 mole S (32 g)

Question 48

What is the maximum secondary quantum number l in known elements?

Answer 48

3 (corresponding to s, p, d, f)

Question 49

How many bonds does Xe typically form in XeF₂?

Answer 49

2 (though that’s an expanded octet)

Question 50

How do we count phases in a reaction?

Answer 50

Each distinct physical state (solid, liquid, gas, or a single aqueous phase)

Question 51

Which concentration unit is used in freezing point depression?

Answer 51

Molality (m, moles solute per kg solvent)

Question 52

What are actinides (actinoids)?

Answer 52

5f‐block elements in the 7th period

Question 53

What is benzene’s formula?

Answer 53

C₆H₆

Question 54

What is the IUPAC name of acetylene (C₂H₂)?

Answer 54

Ethyne

Question 55

What do benzene (C₆H₆) and ethene (C₂H₄) have in common?

Answer 55

Their carbons are sp²‐hybridized

Question 56

How many bonds does N₂ have?

Answer 56

A triple covalent bond

Question 57

Which orbital is n=3, l=2, m=+1?

Answer 57

A 3d orbital

Question 58

Name another octet‐rule exception.

Answer 58

SF₆, BF₃, or PCl₅

Question 59

How does gas density vary with temperature (at constant P)?

Answer 59

Inversely; ρ ∝ (M / T)

Question 60

Which family does ethylene (C₂H₄) belong to?

Answer 60

Alkenes

Question 61

What forms from H₂CO₃ + Mg(OH)₂?

Answer 61

MgCO₃ (magnesium carbonate) + H₂O

Question 62

What is the simplest cubic cell structure?

Answer 62

8 corner atoms (1 net atom/cell)

Question 63

How many molecules are in x moles of a substance?

Answer 63

x × 6.022×10²³

Question 64

When does ΔH>0 and ΔS>0 favor spontaneity?

Answer 64

At sufficiently high T (TΔS > ΔH)

Question 65

How does Lewis define a base?

Answer 65

An electron pair donor

Question 66

Which pair definitely forms an ionic bond?

Answer 66

An alkali or alkaline‐earth metal + halogen (e.g., CaF₂)

Question 67

What is a tertiary carbon?

Answer 67

A carbon bonded to three other C atoms

Question 68

Which law explains irreversibility of processes?

Answer 68

The second law of thermodynamics (entropy increase)

Question 69

What is a hydride?

Answer 69

A compound where H is in the −1 oxidation state (e.g., LiH)

Question 70

What is the Born‐Haber cycle used for?

Answer 70

It breaks down the formation of an ionic solid into steps to find lattice energy

Question 71

How to form an ester?

Answer 71

Carboxylic acid (R–COOH) + alcohol (R′–OH) → ester (R–COOR′) + H₂O

Question 72

Which is an ionic compound among CaO, CO₂, H₂O?

Answer 72

CaO (ionic); CO₂/H₂O are covalent