AP CHEM UNIT 4 Particles and Solutions

Mixture

physical combination of two or more substances

Solution (homogenous mixture)

Solute particles are evenly dispersed in a solvent

Solution (heterogenous mixture)

un-evenly distributed solute particles in a solvent

How to calculate molarity 

moles of solute/liters of solution 

What causes an ionic compound to dissolve in water? 

The attraction between ions and the oppositely charged parts of polar water molecules 

How do polar solvents dissolve ionic solutes?

Polar solvent molecules surround the solute's ions, stabilizing them in solution

What is chromatography?

A technique used to separate the components of a mixture by passing them through a stationary phase and a mobile phase

What is the mobile phase?

a liquid or gas that carries the sample and moves the compounds through the stationary phase, causing separations

What is a stationary phase?

the stationary phase is the substance that remains fixed in place within the chromtagraphic system, creating a surface or a film for the separation of components

In paper chromatography, how do more soluble components behave? 

They travel farther up the paper with the solvent 

In paper chromatography, how do less soluble components behave?

They remain closer to the origin

Why is polarity important in chromatography?

determines how strongly solute molecules interac with the stationary vs mobile phases

Why do polar elements with OH groups dissolve readily in water?

Hydrogen bonding between the OH and water molecule allows it to be soluble 

What type of intermolecular force stabilizes nonpolar solutes in nonpolar solvents 

London Dispersion forces ( because only non-polar have London dispersion) 

In paper chromatography with water as the mobile phase, which compounds move the fastest?

What is the stationary phase in paper chromatography?

The paper (cellulose), which is polar

What is the mobile phase in paper chromatography?

The solvent (can be polar or nonpolar depending on experiment)

If the mobile phase is polar, which compounds travel faster/further

nonpolar compounds, because they interact less with the polar paper 

What is the stationary phase in column chromatography?

Packed beads 

What is the stationary phase in TLC (thin-layer chromatography) 

polar plates 

What is the electromagnetic spectrum 

The range of all types of electromagnetic radiation, organized by wavelength or frequency

How does wavelength relate to frequency in the EM spectrum? 

Wavelength and frequency are inversely proportional: longer wavelength → lower frequency, shorter wavelength → higher frequency 

What type of EM radiation has the shortest wavelength?

Gamma rays

What type of EM radiation is just beyond visible red light?

infrared

What type of EM radiation is just beyond visible violet light?

Ultraviolet

How is photon energy related to wavelength?

Photon energy increases as wavelength decreases

What does frequency measure?

the cycle of light hitting to complete a full cycle 

Excited electrons have

Absorbance is directly proportional to concentration

equation used to find energy in terms of wavelength

E=hc/λ

1 ev =1.6022×10^-19

to convert ev to J

more solutes

higher absorption

More OH bonds means 

more soluble in water 

The lower amount of solutes means

less light absorption

Microwave

rotational transitions

Infrared region

vibrational to create energy, but  cannot eject

rotational transitions

causes friction, but cannot eject 

Highest energy in EM spectrum

Weaker Imfs and lower boiling points

distills first than stronger IMFs, resulting in lower energy requirement for phase change.

The total pressure of the gases in the mixture is the sum of the initial pressures

pressure only depends on the total amount of gas when volume and temperature are held constant.

The energy of a photon is ___  proportional to its frequency and ___  proportional to its wavelength

directly, inversely 

a wavelength range of 10-5 or 10-8 has more energy

10-5, because it has a shorter wavelength and therefore a higher frequency

A jump in ionization energy (Ev) indicates what?

that electrons are being removed from a stable, filled electron shell.