unit 1 Flashcards
whats the 1st law of thermodynamics (law of conservation of mass)
matter, energy or charge cannot be created or destroyed
whats a pure substance
something that has the same composition and properties throughout (elements and compounds)
whats a element
substances composed of all the same atom
whats a compound
contains two or more different elements chemically combined in fixed proportions, and can be broken down by a chemical change
whats a mixture
a combination of two or more pure substances that can be separated by physical means
whats a homogenous mixture
a mixture in which different substances are blended evenly throughout (ex. glass cleaner)
whats a heterogenous mixture
a mixture in which different materials are easily distinguishable (ex. pizza)
whats filtration
seperation of a heterogenous mixture
whats crystallization
separation by different freezing points or vapor pressure (evaporation)
whats disilliation
separation based on different boiling points; different from evaporation
whats chromatography
separation based on substances affinity for a medium
whats accuracy in chemistry
how close the measurement is to the actual value
whats precision
how reproducible the measurements are
whats % error
((measured - accepted)/accepted) x 100
what are the two different types of energies
potential energy and kinetic energyw
what is potential energy
stored energy
what is kinetic energy
energy of motion
what are some forms of energy
heat, light, electricity, chemical, nuclear
whats the law of conservation of energy
energy cannot be created or destroyed
what is heat not and what is it actually
heat is not temperature, it is the energy itself
what is temperature
the amount of heat a material has
what is the equation to find heat energy
q = MCΔT
what is temperature a measure of
average kinetic energy of a material
what is the celsius scale based on
the freezing point (0c) and boiling point (100c) of water. zero degrees celsius doesnt mean zero average kinetic energy
what is the kelvin scale
0K = the absolute 0, where all kinetic energy has ceased.
whats the formula to convert C to K
K = C + 273
whats specific heat
its a physical property of matter, and is how a material response to the addition or loss of heat, in joules per gram Celsius
its the amount of heat energy that is required to raise 1g of a substance by 1c
what is freezing and what is the nature of it
liquid to solid, exothermic
what is melting and what is the nature of it
solid to liquid, endothermic
what is condensation and what is the nature of it
gas to liquid, exothermic
what is vaporization and what is the nature of it
liquid to gas, endothermic
what is sublimation, and what is the nature of it
solid to gas, skipping the liquid intermediate phase. it is endothermic
what is deposition, and what is the nature of it
gas to solid, skipping the liquid intermediate phase. it is exothermic.
what is the heat of fusion (Hf)
the amount of heat energy (in J) required for a material to change from solid to liquid (melting).
its equal to the temperature of where it starts to flatline
what is the heat of vaporization (Hv)
the amount of heat energy (in J) required for a material to change from liquid to gas (boiling).
its equal to the temperature of where it starts to flatline.
what phases is the material at the heat of fusions
solid and liquid
what phase is the material at the heat of vaporization
liquid and gas
what is the added heat energy being used for in a slanted part of a heat graph
to increase the average kinetic energy
what is the added heat energy being used for in a flat part of a heat graph
to break the bonds of a substance, and change phases. average kinetic energy stays the same.
whats an exothermic reaction
when energy is released, in phase changes such as freezing and condensation
whats an endothermic reaction
when energy is absorbed, in phase changes such as melting and boiling
what does a catalyst do
speeds up the reaction without being used up or changed
what is chemical energy
chemical energy is stored potential energy in a chemical bond, which hold compounds together.
what happens when bonds are broken and new bonds are formed
the amount of energy that is stored changes
what happens if there is a change in y value
change in average kinetic energy
what happens if there is no change in y value
change in potential energy
whats enthalpy (heat of reaction)
the amount of heat energy absorbed or released during a chemical change. known as ΔH (heat of products - heat of reactants)
how to identify a a exothermic reaction and what does the ΔH look like
if the products have less energy then the reactants. the extra energy is released into the surroundings.
The ΔH would be negative
how to identify a endothermic reaction and what does the ΔH look like
if the products have more energy then the reactants. the extra energy is absorbed from surroundings.
The ΔH would be positive
what is the potential energy in a exothermic reaction for the reactants and products
reactant potential energy is higher then the potential energy of the products
what is the potential energy in a endothermic reaction for the reactants and products
reactant potential energy is lower then the potential energy of the products
what is activation energy (Ea)
the energy required to initiate a chemical reaction.
what does the activation energy (Ea) ensure?
it ensures that when molecules collide, they have enough energy for a effective collision (for them to react and become products)
how does Ea change with a catalyst
it decreases
how does catalyst effect ΔH
it doesn’t
what is an example of a catalyst
an enzyme
what’s kinetic molecular theory
KMT for an ideal gas states that:
1. they are in random, constant, straight-line motion
- they are separated by great distances relative to their size (but the gas particles themselves have negligible volume)
- they have neither attractive nor repelling forces between them
- have collisions that may result in a transfer of energy between gas particles, but the total energy of the system remains constant.
- the collisions are perfectly elastic
whats ideal gas concept
model to explain the behavior of gases. gases are closest to behaving as an ideal gas at low pressures and high temperatures
what happens when molecules collide
they can bounce apart or react to form something new
whats collision theory
if particles collide with the proper energy and orientation, a chemical reaction (change) can occur
what does kinetic molecular theory describe
the relationship of pressure, volume, temperature, velocity, frequency and force of collision among gas molecules
whats pressure
a forced exerted on a specific area (force divided by area)
how do gases exert pressure
by colliding with other gas molecules or their container. if there is no collisions, there is no pressure, and this is known as a vacumn
what is the kinetic-molecular view of gas pressure
gas pressure comes from the force of molecular collisions
anything that increases the # of collisions will increase the pressure
what are all the units for pressure
pascals (pa) at sea level: 101.3 kPa
mmHg (millimeter of mercury) at sea level: 760 mmHg
Torr (torr) at sea level: 760 Torr
atmospheres (atm) at sea level: 1 atm
what is vapor pressure
pressure of vaporizing liquid exerted by liquid
how does boiling occur in terms of vapor pressure
atmospheric pressure pushes down on the liquid, keeping the molecules in the liquid
if VP = atmospheric pressure, liquid molecules can escape out of the liquid and boiling will occur
what happens if you increase temperature
there will be an increase in energy, which will allow for boiling
what happens if you increase elevation
atmospheric pressure will decrease, therefore allowing for less energy to be needed to trigger boiling.
what happens to boiling point if you increase vapor pressure (VP)
boiling point decreases
what happens to ΔT as VP increases
ΔT increases
what happens to ΔT as BP increases
ΔT decreases
whats volume
the amount of space a gas occupiesw
whats velocity
how fast the particles are moving (speed)
what does increasing temperature do in terms of velocity
it increases the velocity of the particles
what does increasing weight do in terms of velocity
it decreases the velocity
whats STEVEN
same temp = equal volume, equal # of particles
whats avogadro hypothesis
STEVEN
equal volumes of gas at the same temperature and pressure contain and equal number of particles (STEVEN)
whats boyle’s law
the pressure will increase as volume decreases if temperature is constant (ex. a piston)
P1V1 = P2V2
whats charles’s law
the volume will increase as temperature increases if the pressure is constant (ex. a hot air balloon)
V1/T1 = V2/T2
why does charles law happen
it happens because the container must get bigger for the pressure to stay the same. increase in temp = increase in collisions with container wall
if the walls are flexible, they’ll get pushed back, and the gas expands
whats the combined gas law formula
(P1)(V1)/T1 = (P2)(V2)/T2
whats the combined gas law
when there is a change in temperature and pressure. this doesn’t match
what is the standard temperature
0c or 273K
what is the standard pressure
1atm/101.3kPa/760torr/760mmHg
how do you seperate a homogeneous solution
distillation, chromatography, crystillization
