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Chem 111 PSU Final
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Gravity
Terms in this set (123)
spectroscopy
the study of the interaction between electromagnetic radiation and matter
energy transitions observed in experiment 2
Balmer series transitions
White light
the tiny band of the electromagnetic spectrum that the human eye can see (400nm-800nm)
Colors of the spectrum from highest to lowest frequencies
Violet - Blue - Green - Yellow - Orange - Red
discharge tube
used to observe the spectrum of the element
spectrum changes with slit width and distance from source
thinner width = more precise measurements
Closer to source = light is more intense
Calibrate spectroscope
Point the spectroscope at the light and observe the three strongest emission lines on the graph paper. Plot a graph of these lines and determine the slope to find the wavelengths.
fundamental reason why a substance absorbs visible light
the radiation possesses the energy needed to move an electron from its ground state to an excited state (low to high)
technique of calorimetry
process of set solutions of known concentrations of some light absorbing substance is placed in a series of containers and unknown concentrations are compared to the calibrated set
process that removes energy from excited food dye molecules in aqueous solution
solvent molecules bumping millions of times in aqueous solution against excited food dye molecules removes energy
dilution equation to solve dilution problems
C1V1=C2V2
Observations of OTO
Chlorine reacts with OTO that produces a yellow color. The carbon pulls out the chlorine. The more intense yellow color means there was more chlorine in the tap water.
2 reasons why alum is expensive to produce
1. deposits outside of US
2. energy intensive
2 uses for alum
1. pulp
2. paper
Difference between corrosion of iron and corrosion of aluminum
Corrosion of aluminum- the metal reacts with O2 to form a layer of Al2O3 that protects from further corrosion, corrosion of iron does not
What is alum
generic name for variety of aluminum compounds that are combinations of aluminum sulfate and a group 1A metal sulfate
H2SO4 is added to aluminum can a bubbles are observed- explains why acids corrode most metals
3H2SO4 (aq) + 2Al (aq) = Al2(SO4)3 (aq) + 3H2 (g)
H2 is a gas-bubbles
presence of (SO4)2-, K+, H20, Al3+
sulfate= alum and BaCl2, white precipitate
K & H20= flame test, flame turned purple and popping noise of H20 separating
Al3+= alum + KOH, checking for Al(OH)4 precipitate, Al acidic pH
Melting point test on alum
1. confirms the identity of the compound
2. measures its purity- impurities decrease the melting point (bigger range)
reaction involving Crystal Drano
2Al (s) + 2NaOH (aq) +6H20 (l) = 3NaAl(OH)4 (aq)
small calorie (c)
scientific calorie
1 cal= energy required to raise the temp of 1 gram of H20 by 1°C at 1atm
food calorie (C)
1000c
like dissolves like
Polar solvents dissolve polar solutes (NaCl in H20) and non-polar solvents dissolve non-polar solutes
Like dissolves like with ethanol, pentanol, kerosene, and water
KI was added to each. Since KI is polar, it would dissolve in polar solvents. The polarity was ranked on how quickly KI dissolved.
aqueous sodium carbonate is basic
Na2CO3 (aq)+2H20(l) = 2NaOH(aq)+CO2 (aq)+H20(l)
aqueous aluminum chloride is acidic
AlCl3(aq)+3H20(l) = Al(OH)3(aq)+3HCl(aq)
aqueous potassium iodine is neutral
KI(aq)+H20(l) = KOH(aq)+HI(aq)
aqueous ammonia/ammonium hydroxide - complicated name
if dissolved, ammonia gas in water comes out of solution very quickly and becomes NH3 (g) again
4 types of reactions
acid/base
precipitation
redox
complexation
acid/base
produces salt + H20
precipitation
forms insoluble product
redox
chemical species changing oxidation states
complexation
forms a complex ion (metal ion with other substances covalently bonded to it)
soluble
Na+, K+, NH4+, Cl-, Br-, I-, NO3-, (SO4)2-
insoluble
OH-, (PO4)3-, (CO3)2- (expect with Na+, K+, NO4+)
advantage of BTB indicator over red cabbage extract
BTB is kept longer and color changes quick
serial titration
add 1 drop to the first well, 2 drops to the next, etc. to compare drops
single well titration
keep adding drops to the same well until it changes color
titration with HCl and NaOH using BTB indicator
HCl(aq)+NaOH(aq) = NaCl(aq) +H20(l)
H+(aq)+OH-(aq) = H20(l)
endpoint: yellow turns dark blue
back titration
faster; excess HCl is added to dissolve CaCO3, then unreacted acid is titrated with a standard solution of base
absorption capacity
(mass of CO2 absorbed)/(mass of absorber)
2 sources of atmospheric carbon dioxide
1. burning coal
2. burning oil
2 situations where removal of CO2 from air is important
1. spacecrafts
2. submarines
Rf values for developed chromatograms
(distance moved by the component)/(distance moved by the mobile phase front)
component- vertical distance
phase front- horizontal distance
stationary phase
porous paper
mobile phase
paper placed in a tank and the mobile phase is pulled through the paper by capillary action- like dissolves like (polar)
Vr (retention volume)
measure of the amount of mobile phase required to remove each component of the mixture from the column
larger Vr, more strongly the component interacts with stationary phase
Define Calorimetry
measurement of amount of heat evolved or absorbed in a chemical reaction, change in state, or a formation of solution
Small calorie(c) compared to Food Calorie(FC)
1c=1000FC
calorie
Amount of energy needed to raise temperature 1 gram of water 1 degree C
Explain the purpose of setting up a discharge tube
The purpose is to ionize the atoms or energize them so they emit light. This light can then be viewed through a spectroscope where the wavelength will be determined. Once determined the wavelength is used to figure out the element.
what is 2/3's rule standard deviation?
2/3 of the data points that fall around the average
What is alum?
It is a double salt combination of aluminium sulfate and a group 1A salt, ammonium ion or sulfate ion
H2SO4 is added to the aluminum can and bubbles are observed what is the equation?
2Al (s) + 3H2SO4 (aq) --> 3H2 (g) + Al2(SO4)3 (aq)
Write why carbonated beverages are acidic
CO2 (g) + H2O (l) = H2CO3 which is acidic
what is the Test for presence of SO4 2-
add BaCl2 and a precipitate should form if SO4 2- is present
what is the test for H2O and K+
flame test K+- flame should turn light purple
H2O- crackling
what is test for Al3+
add KOH to produce AlOH3 to form a gelatinous precipiate
What two things did the melting point test on the alum tell us?
This test is done in order to confirm the identity and purity of the sample impurities tend to lower the melting point.
write out the reaction involving crystal draino
Al2O3 + 2KOH + 3H2O = 2KAlOH4
explain the like dissolves like principle and know some specific examples that document your explanation
If two substances have identical IMF's they will most likely dissolve. The more different the IMF's the less likely they will dissolve H2O and NH3 both have LDF's and H-boding so it dissolves
use like dissolves like to explain
ethanol/water
pentanol/water
kerosene/water
ethanol and water- both are polar so they dissolve
pentanol and water- pentanol is slightly polar so it dissolves but at a slower pace
Kerosene and water- kerosene is non-polar therefore it does not dissolve
accuracy
A description of how close a measurement is to the true value of the quantity measured.
actual yield
The amount of product actually obtained in a reaction
Anion
an ion with a net negative charge
atom
the smallest piece of an element hat can enter into chemical combinations
Avogadro's number
the number of 12C atoms in exactly 12 g of 12C it is equal to 6.022 *10^23
Bronsted acid
A substance capable of donating a proton (H+)
Bronsted base
A substance capable of accepting a proton (H+)
Buffer solution
A solution that has the ability to resist small changes in pH upon the addition of small amounts of either acid or base
Catalyst
A substance that increases the rate of a chemical reaction without itself being consumed
Cation
An ion with a net positive charge
Chemical kinetics
The area of chemistry concerned with the speeds or rates at which chemical reactions occur
Chemical reactions
Processes in which one or more substances are converted into other substances
compound
A substance composed of atoms of two or more elements chemically untied in fixed proportions
covalent bond
A bond in which two electrons are shared by two atoms
density
The mass of a substance divided by its volume
diffusion
the gradual mixing of one substance with another due to random molecular motion
Dilution
A procedure for preparing a less concentrated solution from a more concentrated solution
Electrolyte
A substance that, when dissolved in water, results in a solution that can conduct electricity
Electronegativity
The ability of an atom to attract electrons toward itself in a chemical bond
Element
t cannot be separated into simpler substances by chemical means
Endothermic processes
Processes that absorb hear from the surroundings
Energy
The capacity to do work or to produce change
Enzyme
A biological catalyst
Equilibrium
A state in which there are no observable changes as time goes by
Excess reagents
one or more reactants present in quantities greater than those needed to react with the quantity of the limiting reagent
Exothermic process
processes that give off heart to the surroundings
First law of thermodynmics
Energy can be converted from one form to another but never created/destoyed
Full ionic equations
A reaction equation that shows all soluble compounds in their ionic forms
Hess's law
When reactants are converted to products the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps
Hydrogen bond
A special type of dipole-dipole interaction between molecules containing hydrogen bonded to an electonegative element. The most important example involve nitrogen, oxygen, and fluorine. For instance, the attraction between a hydrogen on one water molecule and the oxygen atom on a second water molecule would constitute a hydrogen bond.
Inorganic compounds
compounds other than organic compounds
Ion
A charged species
Ionic bond
The electrostatic force that holds ions together in an ionic compound
Ionic compound
A chemical compound composed of cations and anions combined so that the total positive and negative charges are equal
Ionization energy
The minimum energy required to remove an electron from an isolated atom (or an ion) in its ground state.
Isotopes
Atoms having the same number of protons but different number of neutons
Joule
Unit of energy given by newton meters
Kinetic energy
Energy available because of the motion of an object
Le Chatleier's principle
If an external stress is applied to a system at equilibrium the system will adjust itself in such a way as to partially offset the stress
Limiting reagent
the reactant used up first in a reaction
Macroscopic properties
Properties that can be measured directly
Metals
elements that are good conductors of heat and electricity and have the tendency to form positive ions in ionic compounds
Mixture
A combination of two or more substances in which the substances retain their identity
Molar mass
the mass of one mole of atoms, molecules, or other particles
Molecular compound
A compound consisting of atoms that are covalently bonded
Molecular equation
A reaction equation that shows the complete chemical formulas of all reactants and products
Molecule
A neutral aggregate of two or more atoms held together by covalent bonds
Net ionic equation
A reaction equation in which all spectator ions are removed leaving only the ions and molecules directly involved in the reaction
Non-electrolyte
A substance that, when dissolved in water gives a solution that is not electrically conducting
Nonmetals
Element that are usually poor conductors of hear and electricity, and have the tendency to gain electrons and form negative ions
Non-polar bond
A covalent bond in which the electrons are equally shared by two atoms, so there are no positive and negative ends
Oxidation number
the number of charges an atom would have in a molecule if electrons were transferred completely in the direction of the atoms with the higher electronegativity
Oxidation reaction
The half reaction that involves the loss of electrons
Oxidizing agent
A substance that can accept electrons from another substance or increase the oxidation number in another substance
pH
The negative logarithm of the hydrogen ion concentraiton
Specific heat
The amount of heat energy required to raise the temperature of on gram of substance by one degree
Titration
The gradual addition of a solution of accurately known concentration to another solution of unknown concentration until the chemical reaction between the two solutions is complete
Examples of line spectra
line spectra of hydrogen
examples of continuous spectrum
rainbows and light from a light bulb
absorbed colors
colors not seen are absorbed
observed colors
colors seen are reflected
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