MCAT Physics/Chemistry Tests

In extraction purification, which compound will remain in the organic layer and which will remain in the non organic layer?

Nonpolar molecules will move to the organic layer and polar molecules will move to the nonorganic layer 

Are ionic compounds polar?

yes

Avogadro’s number

6.02 × 10²³

Normality

is the number of equivalents of reactive species per liter of solution, for which we must define the reactive species. Often used to express the concentration of H⁺ or OH⁻ ions produced in acid-base reactions

Ex. HCl generates one equivalent of H⁺ ions and one equivalent of Cl⁻ ions per mole

H₂SO₄ generates two equivalents of H⁺ ions and one equivalent of SO₄²⁻ ions per mole.

Do cations and anions have smaller atomic radii? 

cations 

Atomic radius trend on the periodic table

Down and Left

Electronegativity trend on the periodic table

Right and Up

Ionization energy trend on periodic table

Right and Up

Ionization energy

the energy required to remove an electron from a isolated atom

Electronegativity

an atom’s tendency to attract electrons when it is already in a bond

Fatty acid chain structure

carboxyl group with a hydrocarbon chain and a methyl group at the end

Radioactive decay 

The process by which an unstable atomic nucleus spontaneously loses energy by emitting radiation. The loss of energy results in the nucleus becoming more stable, often transforming the atom into a different element

What are the four kinds of radioactive decay? 

Alpha decay, beta (+ and -) decay, gamma decay, and electron capture 

alpha decay

In this mechanism of decay, an alpha particle containing two protons, two neutrons, and two electrons

beta minus decay

In this mechanism of decay, a neutron is converted into a proton in the nucleus, and a β⁻ particle (an electron) is ejected to maintain charge balance

beta plus decay

In this mechanism of decay, a proton is converted into a neutron and a β⁺ (positron) molecule is emitted to preserve charge

gamma decay

This mechanism of decay involved the emission of a high energy photon (gamma ray) from an excited nucleus

electron capture 

In this mechanism of decay, a proton in the nucleus grabs an electron, converting a proton into a neutron. 

Why can ions not cross the cell membrane?

Ions are charged particles, making them hydrophilic

Magnetic field strength equation

B = µ_oI/2r

B is the field strength

µ_o is the permeability of space (a constant)

I is the electrical current through the circuit

R is the radius of the loop.

Work equation

W = Fdcos(ø)

Work-Energy Theorum

this theory states that work is equal to the change in kinetic energy of a system

W=∆KE

Electromagnetic spectrum

Kinetic energy formula

KE = 1/2mv²

Formulas for power

P = W/t

P = F v

surface tension

a force that should be understood as the property of the surface of a liquid that allows it to resist an external force

what makes a good nucleophile?

an electron-rich species that is effective at donating a lone pair of electrons to an electron-poor atom.

Nucleophilicity is governed by four main factors: charge, electronegativity, steric hindrance, and solvent

acetyl group

Relative reactivity 

alcohols and ethers< aldehydes and ketones < amides < esters and carboxylic acids < acid halides 

imine

specific gravity

a dimensionless constant referring to how dense a substance is compared to water, defined as ρ/ρ_water

sulfonyl

urea

How to calculate pH

[H⁺] = 0.1 M = 1 x 10^-1 M

pH = -log[1 x 10^-1] = 1

pOH = 14-pH

viscosity 

resistance to flow 

Poiseuille’s law

used to describe laminar flow of incompressible fluids through a long cylindrical tube.

Contains 5 variables:

the flow rate (Q), 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)