Chem unit 1 test practice

Matter

anythig that has a mass (amount of matter) and volume (takes up space)

two types of matter

• pure substance

• mixture

Pure substance definition

matter in which the particles that make it up are all the same

elements

• type of pure substance with only one type of atom

ex: gold (Au) Lead (Pb) Fluorine (F)

• can’t be changed without chemical reaction

Compounds

• Type of pure substance with two or more types of atoms

• ex; Water (H2O) Phosphate (PO4) salt (NaCl)

can be seperated easily without chemical reaction

Mixtures

matter which contains more than one type of particle

Two types of mixtures

• heterogeneous mixture

• homogeneous mixture

heterogenous mixture

not evenly distributed

often distinguishable

ex: sand+water, salt+pepper, concrete

homogenous mixture

evenly distributed

connot be easily seperated (complex methods like distillation or evaporation)

solid sugar dissolved by water (see why in notes)

physical properties

can be observed without changing identity of substance

• colour, density, lustre, conductivity, heat or electricity, soft or hard, brittle or malleable, state of matter at room temp, melting + boiling point

Chemical properties

how the substance reacts of other substances, therefore changing identity

• flammable, reacts with acid, rusting

Physical change

• change of state but no substance with different composition is formed

• when a substance changes state, its physical state since identity stays the same (therefore when warming water, the chemicals stay the same.)

• chemical make-up doesn’t change when: we boil, freeze, melt, cut, tear, heat a substance

Chemical change

change when new substance is formed

• change in colour, endothermic, exothermic, 2 clear liquids creat cloudy mixture (precipitate forms)

Density

physical property that describes mass per unit volume of substance

Kinetic Molecular Theory of matter

• matter consists of small particles that have a mass

• have space between particles

• strength of IMF increase when particles are closer

• movement of particles

• Temperature of substance is based off of the kinetic energy of particles

When the temperature of liquid is increased….

• diffusion occurs more readily

• kinetic energy is increased

When temperature of solid increases…

• velocity increases slightly

• KE increases

• therefore more room between particles

Nature of solids: solids

• fixed location/shape

• strong IMF

  • only vibrations of particles in fixed posistions

two types of solids

• crystalline

• amorphus

crystalline definition + 4 types

• solid with particles that are organized and repeating

• Molecular (I2, S4), Ionic (NaCl, CaF2), covalent-networking (graphite and diamonds) , metallic (Cu Ag)

Ionic

• opposite ions attract

• opposites are closer, similar ions are farther away

• strong and brittle, which means it has high melting points because of their strong ionic bonds

• crystal arrangement give stability

Molecular

• close together by IMF

• softer + low melting points because of weak IMF that can be overcomed

• can be atoms or molecules

covalent networking

• formed with strong covalent bonds

• the covalent bonds art networked around the crystalline solid

Amorphus

• Lack of 3D arrangement of particles

• might be rigid and solid, but doesn’t behave like crystalline solid

• ex: plastics, glass, rubber

Postulates of Kinetic Molecular Theory of gases

• Small particles that contain a mass

• big distance between those particles (and because of this, it’s easily compressible from the particles being very far apart.

• Rapid, constant, random motion of gas particles

• Collisions between gas particles and wall of container that become perfectly elastic

• temp based on KE

• IMF are really weak, which means the attractive forces are at zero

Postulate #3: elastic collision is when…

KE is conserved during a collision, which means no energy is lost.

Postulate #3: Inelastic collision is when…

KE is not conserved during a collision, and some of it is absorbed.

pressure

force per unit area

Postulate #4: Collision of gas particles exert ______ and result in ________

it exerts force and results in pressure

inelastic= particles slow down, and it so does the pressure

more gas = pressure increases

when the KE increases, what happens with the temperature and so forth?

the temp increases

the velocity increases > particles move rapidly.

with particles moving rapidly, it creates forceful collisions, which creates more pressure.

Physical properties of gas

• No definite shape or volume

• Contains mass, but is least dense

• Compresses easily

• Diffuses easily

• Fills its container

• Pressure of gas is dependent on temp

Explain what happens to evaporation when container is open vs. closed

when container is open = evaporation exceeds the rate of condensation

when container is closed + evaporation + condensation, thus creating a dynamic equilibrium

Sublimation vs. deposition

Sublimation = solid to gas (ex; dry ice)

Deposition = gas to solid (ex; when snow melts, and the temp stays below freezing point.)

freezing + Freezing point

temperature at which the solid is formed ( liquid to a solid, also called solidification)

melting + melting point

• when a solid turns into a liquid

  • and the melting point is the temperature at which a liquid forms

Vapourization + boiling point

• when a liquid turns into a gas

• and the temperature at which a liquid is turning into a gas forms

• the temp at which vapour pressure = atmospheric pressure

Condensation + condensation point

• when a gas turns into a liquid

  • the temperature at which a vapour condenses

Amount of energy to separate solid particles

• heat of fusion

The amount of heat necessary to vaporize a given amount of liquid at its boiling point

• heat of vapourization

Vapour pressure

Pressure of vapour above liquid in a closed container

what happens when vapour pressure equals and exceeds atmospheric pressure

gas bubbles will rise to the surface of water and burst will releasing gas (boiling)

relationship between vapour pressure and temperature, explain why

• Temperature is directly proportional to vapour pressure

• when temperature decreases, vp decreases, same as opposite

  • when temperature increases > KE increases > vapour pressure increases because the particles are rapidly moving, with gas bubbles making their way to the surface of liquid to burst

what’s the relationship between vapour pressure and IMF?

• inversely proportional

• weak IMF = higher vapour pressures, evaporate easier, and lower boiling points