Phys Deck 1: Lab Techniques, Acids/Bases, Circuits, Gases, Phase Changes

What is the stationary phase in TLC?

Polar silica gel (or alumina)

What is the mobile phase in TLC?

A nonpolar (or less polar) solvent that moves up the plate by capillary action.

Which compounds travel farther on a TLC plate?

Nonpolar compounds

Why do polar compounds stay near the bottom in TLC?

They form stronger interactions with the polar silica and move more slow

What does a high Rf value indicate?

Compound traveled farther

Usually less polar

If pH < pKa, is a group protonated or deprotonated?

Protonated

f pH > pKa, is a group protonated or deprotonated?

Deprotonated

Which side of the pKa favors the protonated form?

The lower pH side

What is the equation for capacitance?

C=κε0​A​/d

Capacitance increases with

larger plate area

dielectric constant

Capacitance decreases with:

greater plate separation

What happens to capacitance if plate area increases?

Capacitance increases

What happens to capacitance if plate separation increases?

Capacitance decreases

On the MCAT, what biological structure acts like a capacitor?

The cell membrane

Why does inhibiting the Na⁺/K⁺ pump decrease membrane voltage?

Because ion gradients slowly disappear, so less charge is stored across the membrane

What happens to the resting membrane potential when the Na⁺/K⁺ pump is inhibited?

It becomes less negative (depolarizes)

What equation is used to calculate percent increase?

new-original/original *100

Which gas law describes pressure, volume, moles, and temperature?

PV=nRT

At what pressure is the normal boiling point measured?

1 atm

What does the liquid-gas boundary on a phase diagram represent?

Boiling and condensation equilibrium.

How do you convert C to K?

C+ 273

What is the torque equation?

τ=rFsinθ

For rotational equilibrium, what must be true?

Clockwise torque = counterclockwise torque

Net torque=0

If one object is heavier, where should it be placed relative to the pivot?

Closer to the pivot

What equation relates energy and frequency?

E=hf

If energy stays constant, what happens to frequency?

Frequency stays constant

Heat transfer through direct contact is called...

Conduction

Heat transfer through moving fluids is called...

Convection

What is forced convection?

Convection caused by an external source

Heat transfer through electromagnetic waves is called...

Radiation

Does dissolving an ion automatically change its oxidation state?

No

Oxidation state only changes through a redox reaction

What happens when a common ion is added to an equilibrium?

The equilibrium shifts to consume that ion

-Adding a product ion forces the equilibrium position to move in reverse to use up the extra ions.

What happens to AgI solubility if NaI is added?

Solubility decreases because of the common ion effect

If one product is removed from a dissolution equilibrium, what happens?

The equilibrium shifts right, causing more solid to dissolve

What does filamentous contamination visible under a low-power light microscope suggest in a cell culture?

Fungal contamination

• Fungi can form visible filamentous hyphae.

• Bacteria and viruses are too small to see with a low-power light microscope