Chem 111 psu final exam
Terms in this set (111)
measurement of amount of heat evolved or absorbed in a chemical reaction, change in state, or a formation of solution
What does the E m c and delta T stand for in E=mc(delta)T
E- energy c- specific heat constant m- mass or moles (delta T)- change in temperature
Small calorie(c) compared to Food Caloire(C)
Amount of energy needed to raise temperature 1 gram of water 1 degree C
When walking, an average person burns .453 C/(mile*pounds). How many C does a 150-pound person burn after walking a mile? If a peanut releases 5.7 C/g and an average peanut weights about 1 gram, then how many peanuts will you have to eat to walk a mile?
pound = 67.95
67.5 calories * (1 peanut/5.7 calories) = about 12 grams of peanuts
the original study of interaction of radiation and matter as a function of wavelength
A spectrum of light within a certain wavelength (ex. visible light) with no breaks or gaps.
possible source the sun
A line spectrum is an emission spectrum with only certain frequencies. It is produced by excited atoms and ions as they fall back to a lower energy level.
Source tube of excited gaseous element for example a neon sign
What kind of energy transitions were observed in this experiment?
Balmer series transitions (380nm-750nm)
6 series describing the spectral line emissions of hydrogen
Describe white light and know the wavelength range as well as listing the colors from highest to lowest frequency
White light is the small band of radiation that can be see with the human eye. wavelength range is about 400nm-800nm and the highest frequency goes from violet to indigo to blue to green to yellow to orange to red.
parts of a discharge tube
gas at low pressure high voltage source and glass tube
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.
How does slit width and distance from source affect spectrum from a bright source.
getting closer and having a wider slit can make the spectrum of a bight source blurry.
How does slit width and distance from a source affect the spectrum from a weak source
Getting closer and having a wider slit will make the spectrum more distinct and clear.
Outline how to calibrate a spectrscope
To calibrate a spectroscope first i will make a piece of labeled graph paper. Then I will place it in the spectroscope. I will then use light which has known wavelengths like violet at 436 green at 546 and yellow at 580. After i have found out where this light is in relation to the graph lines I labeled i will make a graph with a line of best fit. The line of best fit can be used to determine the wavelength of light.
Equations used to calculate energy wavelength and the Bohr equation
(a) E=hc/(lambda); v=c/(lambda)
(b) E=-R((ni)^-2 - (nf)^-2)
(c) E diff= abs( (first-second)/(.5(first + second)) *100%
Explain the complementary nature of absorbed/observed colors
the absorbed color is the wavelength of light that the object matches like dissolves like and the observed colors is the color that bounces off the substance
What is the fundamental reason why a substance absorbs visible light?
The electron jumps up a specific wavelength that corresponds to the electron transition energy
What process removes the energy from excited food dye molecules in aqueous solution?
It is removed by solvent molecules bumping billions of times per second against the excited food dye molecules
Dilution problem equations
CV=CV A=abc where A-absorbance a- constant b-path length of light c- concentration
Describe the observations of OTO chlorine test kit with tap water and water passed through britta filter
The water taken from the tap is a yellow color because it reacted with OTO. The britta filter removes chlorine so its water should not change color
what is 2/3's rule standard deviation?
2/3 of the data points that fall around the average
is the square root (((value-avg)squared + (value-avg)squared..... + (value-avg)squared)/(number of values - 1))
two reasons aluminium is expensive to produce
The deposits that make aluminium must be mined in other countries
Hall-Heroult process is energy intensive and expensive to carry out
Two uses for alum?
Fire extinguishers, and medicine
explain the difference between the corrosion of iron and the corrosion of aluminum
Iron corrodes completely over a long period of time
aluminum does it very quickly but as it does so it forms a very thin layer of aluminium oxide that protects the rest of it from corroding.
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
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 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
chemical equation as to why sodium carbonate is basic
Na2CO3 + 2H2O = 2NaOH + H2CO3
chemical equation as to why aluminum chloride is acidic
2AlCl3 + 6H2O = 2Al(OH)3 + 3HCl
chemical equation as to why potassium iodide is neutral
KI + H2O = K+ + I- + H2O
4 different types of reactions
redox reaction definition and example
A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction.
Zn + 2HCl = Zn2+ + H2 +2Cl-
acid-base reactions definition and example
When the ions of one compound (acid) interact with the ions of another compound (base), forming a salt and water
NaOH + HCl = H2O + NaCl
complexation reaction definition and example
A reaction between a Lewis acid and a Lewis base
Ag + 2NH3 = Ag(NH3)2
A reaction in which a soid, insoluble product forms upon mixing two solutions.
NaCl(aq) + AgNO3(aq) -----> NaNO3(aq) + AgCl(s)
What are the advantages of using BTB over Red Cabbage
BTB is synthetic and red cabbage is natural. the red cabbage degrades over time and not all of its effects are known
serial titration definition and advantage
What is a titration which is laid out in a 1x12 well tray so that each step can be seen?
no going past the equivalence point
Well titration definition and advantage
a titration where the unknown solution and indicator is added then small amounts of known solution is added till equivalence is reached
Faster for large concentrations
why back titrate?
It is faster; an excess of HCl is added to dissolve the calcium carbonate, then the unreacted acid is titrated with a soluable base to make the standard solution. then the amount of acid used is calculated.
What is water hardness
It is the measure of divalent cations in water usually Mg or Ca
What are two problems caused by hard water?
Scale formation in industrial boilers and the narrowing of pipe due to build up
How do you calculate hardness when done with EDTA titration?
CV=CV and then multiply by 100 g caco3/1mol caco3 and 1000mg caco3/g caco3
What is happening when water is softened by adding either washing soda or an ion exchange resin?
the divalent cations are being replaces by monovalent cations and are then being removed by the resin
What is the Beer lambert law and what is its significance?
A=abc A-absorbance a- molar absorbance b- path length c- concentration
The transmitted light of the lamp through the flame is governed by Beer's law
What are the purpose of standards in AA analysis
Standards are used to make a calibration graph that can then be used to calculate the concentration of the element using the line of best fit
A description of how close a measurement is to the true value of the quantity measured.
The amount of product actually obtained in a reaction
an ion with a net negative charge
the smallest piece of an element hat can enter into chemical combinations
the number of 12C atoms in exactly 12 g of 12C it is equal to 6.022 *10^23
A substance capable of donating a proton (H+)
A substance capable of accepting a proton (H+)
A solution that has the ability to resist small changes in pH upon the addition of small amounts of either acid or base
A substance that increases the rate of a chemical reaction without itself being consumed
An ion with a net positive charge
The area of chemistry concerned with the speeds or rates at which chemical reactions occur
Processes in which one or more substances are converted into other substances
A substance composed of atoms of two or more elements chemically untied in fixed proportions
A bond in which two electrons are shared by two atoms
The mass of a substance divided by its volume
the gradual mixing of one substance with another due to random molecular motion
A procedure for preparing a less concentrated solution from a more concentrated solution
A substance that, when dissolved in water, results in a solution that can conduct electricity
The ability of an atom to attract electrons toward itself in a chemical bond
t cannot be separated into simpler substances by chemical means
Processes that absorb hear from the surroundings
The capacity to do work or to produce change
A biological catalyst
A state in which there are no observable changes as time goes by
one or more reactants present in quantities greater than those needed to react with the quantity of the limiting reagent
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
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
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.
compounds other than organic compounds
A charged species
The electrostatic force that holds ions together in an ionic compound
A chemical compound composed of cations and anions combined so that the total positive and negative charges are equal
The minimum energy required to remove an electron from an isolated atom (or an ion) in its ground state.
Atoms having the same number of protons but different number of neutons
Unit of energy given by newton meters
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
the reactant used up first in a reaction
Properties that can be measured directly
elements that are good conductors of heat and electricity and have the tendency to form positive ions in ionic compounds
A combination of two or more substances in which the substances retain their identity
the mass of one mole of atoms, molecules, or other particles
A compound consisting of atoms that are covalently bonded
A reaction equation that shows the complete chemical formulas of all reactants and products
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
A substance that, when dissolved in water gives a solution that is not electrically conducting
Element that are usually poor conductors of hear and electricity, and have the tendency to gain electrons and form negative ions
A covalent bond in which the electrons are equally shared by two atoms, so there are no positive and negative ends
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
The half reaction that involves the loss of electrons
A substance that can accept electrons from another substance or increase the oxidation number in another substance
The negative logarithm of the hydrogen ion concentraiton
The amount of heat energy required to raise the temperature of on gram of substance by one degree
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
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