Chem 111 PSU Final

Terms in this set (123)

the study of the interaction between electromagnetic radiation and matter

energy transitions observed in experiment 2

Balmer series transitions

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

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

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

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)

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

produces salt + H20

forms insoluble product

chemical species changing oxidation states

forms a complex ion (metal ion with other substances covalently bonded to it)

Na+, K+, NH4+, Cl-, Br-, I-, NO3-, (SO4)2-

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

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

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)

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

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

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

Avogadro's number

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+)

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

A substance that increases the rate of a chemical reaction without itself being consumed

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

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

Electronegativity

The ability of an atom to attract electrons toward itself in a chemical bond

t cannot be separated into simpler substances by chemical means

Endothermic processes

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

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

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.

Inorganic compounds

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

Ionization energy

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

Limiting reagent

the reactant used up first in a reaction

Macroscopic properties

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

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

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

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

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

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

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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