Test mistakes CHEM

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Who is responsible for the electronegativity scale

Linus Pauling

Crystalline solids

(4)
GCN
Ionic
Metal
Molecular

What does Hypervalent mean

More than 8e^- around the central atom

What is Avogadros law

n₁/V₁ = n₂/V₂ (bandit hats)

What is Boyles Law

P ∝ 1/V, P₁V₁=P₂V₂

What are the assumptions for Kinetic theory?

Same T = Same E_k
- collisions with wall are fully elastic
- molecules never collide or interact with each other

What is Daltons Law?

Sum of partial pressures, P_T = ∑p_{n =} P_{1 +} P₂ +…+ P_n

When is a gas most ideal?

When T is high (shorter interactions bec. high E_K) and P is low (more sparse molecules ∴ less interactions)

What is the Work in a contracting gas scnario?

surroundings doing work on the gas (W>0 (+))

What is being referenced when “Gas is heated/cooled” is stated?

±Q

What is a State function?

Depends solely on the current state of the system, not how it got there
∆Func = F_f - F_i e.g. ∆T, ∆P, ∆V, ∆U

What is a Path function (non-state function)

Dependant on the path taken
e.g.
Work is the intergral under the path taken on a PV diagram
Q is also a path fn

What is the eq. for the First Law of thermodynamics

∆U = ∆Q + ∆W_{(surroundings)}

what are the Work on/by surroundings signings?

On = expansion = (-)
By = compression = (+)

To definitively know ∆U you need…

BOTH W and Q

∆_rHº = ? (∆U expression)

∆U + (∆n)RT

Work at constant pressure equation?

-nR(∆T)

What is the Specific Heat mass unit?

J K^-1 g^-1 (per gram!!!)

how do you get C_molar from C_mass? (Heat capacity)

= c_{(mass) x} M_{(molar mass)}

What is Hess’s Law?

The total enthalpy change of a chemical reaction is the same regardless of the number of steps or the path taken

when is ∆_fHº = 0?

when it’s in its “ground state” (most common naturally)
O_2(g), H_2(g), Cu_(s), Br_2(l), I_2(s)

n moles in titration analyte (made solution) given [titre] and vol(titre)?

Titre_{(avg vol.)} x [titrant] = n_{mol titrant}
∴ ratio (i.e. 1:1) in neutralisation rxn will give n mol in analyte titred against (e.g. n in 20mL)

Calorimeter temperature changes from experiment?

|ΔT_hot| > |ΔT_cold​| (because some heat is transferred to the caleromiter

Extrapolation of the data in C_p calorimetry does what?

• Simulates and isolated system (can look back to a point b4 heat escaped)

• Gives gradiants for dT/dt

What is the n quantum number?

Principal number, energy level/shell, {1, 2, 3, 4, 5, 6…}

What is the ℓ quantum number?

Orbital number, angular momentum number, '{n-1}’, s p d f = 0 1 2 3

What is the mℓ quantum number?

the magnetic number, which orientation is the orbital/subshell? {-ℓ, -ℓ + 1,…, 0, … +ℓ - 1, +ℓ}

What is the m_s quantum number?

Spin number, always ±1/2, opposites in each orbital

What are isoelectronic species?

Two ions or atom and ion which have the same amount of electrons

What does a REDOX rxn need?

a change in oxidation number

Metalic bond EN’s?

small ∆EN and small avg EN overall

Ionic bond EN’s?

Big ∆EN between elements

Covalent bond EN’s

Small ∆EN but High overall EN avarage

What is OIL RIG

Oxidation is loss Reduction is gain

what is 1 Bar in Pa?

1 Bar = 1 × 10⁵ Pa

What makes a greenhouse gas special?

When it vibrates (at all) a dipole is induced or the dipole is changed, e.g. H₂O, CO_2, hydrocarbons
most 2 atom molecules aren’t because they dont change e.g. N₂, O₂

Heat and Work are?

Processes by which energy is transferred between a system and its surroundings. (also non-state functions)

First Law of Thermodynamics? (word definitions

Energy can not be created nor destroyed, also the only ways energy can be transferred in or out of a system is Heat or Work

when does Q = ∆_rHº ?

Constant Pressure

When does Q = ∆U

When Volume is constant

∆_rU? (equation)

∆_rHº = ∆_rU + ∆nRT (when ∆T = 0)

What is the C_p to C_V conversion?

C_p = C_v + nR (Important Formula not on sheet)

What’s the ground state of Carbon

Graphite

Who established the energy levels in an atom?

Niels Bohr

Who measured the charge of an electron?

Robert Millikan (oil-drop experiment)

measured the charge to mass ratio of the electron

J. J. Thomson using a cathode ray tube

Who discovered that no two electrons in an atom have all 4 quantum numbers identical?

Wolfgang Pauli

Who proposed the nuclear model of the atom?

Ernest Rutherford — gold foil experiment; small dense positive nucleus, atom mostly empty space

Who wrote that rule about singular orbitals filling up before pairing?

Hund (Hunds rule)

Who experimentally derived V∝T at constant P and n?

Jacques Charles

who experimentally determined that P∝T at constant V and n?

Gay-Lussac

what says that electrons will fill the lowest energy states first?

the Aufbau principle

3 regions of electron density names:

trigonal (all bonding)
bent (1 non-bonging)

4 regions of electron density names:

tetrahedral (all bonding)
trigonal pyrimidal (1 non-bonding)
bent (2 non-bonding)

5 regions of electron density

Trigonal bipyrimidal (all bonging)
See-Saw (1 non-bonding)
T-shaped (2 non-bondong)
Linear (3 non-bonding)

6 regions of electronegativity

Octohedral (all bonding)
Square based pyrimid (1 non-bonding)
Square planar (2 non-bonding)
T-shaped (3 regions non-bonding)

What is polarisability?

How easily an electron cloud can be distorted (Large is easier) - that thing where non-polar things experience attractions (London dispersion forces)

A molecule can form di-oxides and water and contains a C—C bond or many C—H bonds (reactivity)

Flammable

A molecule can form di-oxides and water but does not contain a C—C bond or many C—H bonds (reactivity)

Non-flammable

A molecule can’t form a dioxide or water (reactivity)

Non-flammable (unless it’s C_(s) or H_2(gas)

Enthalpy of rxn formula

∆_rHº = ∑products enthalpy of formation - ∑reactants enthalpy of formation

How many are bonding/non-bonding questions, HNCl₂

3, 1 (always check the amount of bonds first, then look at non-bonding (each bond is 1 from valence))

what does “electron-dot structure for the radical” scream?

One unpaired (singular dot) nonbonding electron (radical)

Who developed the law describing how reaction enthalpy changes with temperature?

Gustav Kirchhoff, Δr​H(T2​)=Δr​H(T1​)+ΔCP​(T2​−T1​)
C_p at diff. temp’s.

Does stoichiometric coefficent effect O.N.?

NO, it has no effect

eq. for radial nodes?

nō.= n - ℓ - 1

eq. for angular nodes?

nō. = ℓ

The atomic theory of matter was first proposed by…?

John Dalton

What other elemental factors is E.N. most closly related to?

Ionisation and electron affinity

How do you test the octet rule is broken?

Odd number of e^-?, <8 electrons around central atom?, period 3+ element?

What are resonance structures?

molecules that have double/triple bonds that can be moved to different places around the central atom, kinda like isomers. e.g. O—S==O, O==S—O

What to do if stuck on Lewis diagram ID question?

count total VALENCE electrons. Check charges/no of bonds

What is Quadrupolar?

No net dipole but dipoles cancel out linearly (but with more than 2 atoms)

What is Octupolar?

tetrahedral molecules (no net dipole but with a more complex structure)

Avg. speed of a N2 molecule in a room

1000km/h, 500m s^-1

Pascal units:

kg m^-1 s^-2

∆n_(g) means??? (∆U to ∆H)

∆number of mol if GAS!!!

Enthalpy of combustion?

ALWAYS negative 0 > ∆_rHº

If a solution warms during a rxn, is the rxn exothermic or endothermic?

exothermic
∆Q_sol > 0
∆Q_sol = -∆Q_rxn
∆_rHº = ∆Q_rxn @ C_p
∴ ∆H < 0
∴ Exothermic