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Transcript of Chemistry Matters
Volume: pertains to how many units of something an object can hold
Density: compaction of particles A B Density A=B
Volume A>B The spacing is equal
Amount of particles are equal
Figure A contains a larger volume (can hold more particles) Mass, Volume, and Density Calculations D= mass _____ volume Formula for calculating
density, mass, volume Find the mass of lead if its density is 11.35 g/mL (V=8cm ) 11.35 ____ 8 ____ = x 11.35 = 90.8g 8 ____ 8 x x= 1.) 2.) 3 volumetric size of cube mass trying to find divide density by volume x=mass found BASICS for Mass, volume, density Units : mass= grams
volume= cm3 or mL
density=g/mL note that 1cm = 1mL 3 Mass, Volume, and Density continued... A B Density A>B
Volume A>B Determining Volume by Water Displacement DATA: Mass: 17.93g
Final Volume: 48.3 mL
Initial Volume: 43.2 mL Bob wants to calculate the volume of sugar he will
be putting in his water to make sugar water. He pours some into his hands and pours some into a graduated cylinder. 48.3 - 43.2 = 5.1 mL ____ 5.1 subtract the final and initial volume
to get the volume of sugar. = 17.93 0.28g/mL this will be the density (use the formula D=m/v) PICTURING
WATER DISPLACEMENT This is the
of the blue guy Particle Pictures of Solid Solids are
don't move around much
have a structure Particle Pictures of Liquids Liquids are
free moving particles
don't have a specific shape Particle Pictures of Gas Gasses are
free moving particles
move around a lot
does not have a shape Law of conservation of mass: matter cannot be created or destroyed Energy and States of Matter- Gases Formulas to know: P P T T V . . . __ 1 V P= pressure
T=temperature Particle Picture of Pressure These blue particles represent the O2
atmospheric pressure. Since there are more
particles present on the outside it creates a greater pressure than the coca cola can withstand.
The coke can has fewer H2 amounts of particles bouncing off the sides, so the pressure outside will crush the coke can. Measuring Pressures 1 atm = 760 mmHg = 101.3kPa = 14.7 psi Q1.) 325 mmHg = x atm 760 mmHg 325 mmHg ___________ ___________ 1 atm x atm cross multiply to get answer Q2.) The barometric pressure in Ohio is 430mmHg. How many atm is this? 430 mmHg 760 mmHg = = __________ __________ x atm 1 atm x= 0.56 atm Pressure and Volume Problems P x V = P x V 1 1 2 2 expands until the pressure drops to 18 kPa. What is the new volume? A gas with a volume of 7.0 L at a pressure of 120 kPa P T V n Initial
Effect 120 18 7.0 x x x 120 kPa x 7.0 L = 18 kPa x X 120 kPa x 7.0 L _____________ 18 X = 46.6L Pressure and Number of Particles pressure and particles have a DIRECT RELATIONSHIP
this means more particles = more pressure
less particles = less pressure Pressure and Volume have an INDIRECT relationship
As Volume goes up, pressure goes down
as volume goes down, pressure goes up Joey's mouth contains 23 units of air particles and has a volume of 123 mL. The pressure reads 11 psi. He accidentally opens his mouth, leaving 18 units of air. What would the pressure in Joey's mouth be? P T V n Initial
Effect X 11 psi x psi 23 units 18 units 11 psi x _______ 23 units _____ 18 units 198 = 23x x=8.61psi (Ratios are very useful) Pressure vs. Temperature Problems When given Celsius it must be changed to Kelvin 0 degrees Celsius roughly = 273 kelvin 0 P T V n Initial
Effect X The pressure inside a tire is 7.8 atm, the temperature inside is 25 C. What will the pressure be if the tire is left outside where the temperature is 38 C. 0 0 7.8 atm x atm 25 C 38 C Pressure and Temperature have a DIRECT relationship
If one goes up then the other does
if one goes down then the other does First convert the Celsius to Kelvin. Add 273 to each.
273+25= 298 - Initial Temperature
273+38= 311 - Final Temperature 7.8 atm x atm 298 K 311 ______ _______ = K 0 0 2425.8 = 298x
x=8.1 atm Work: Work: Work: Work: Work: Work: Volume vs. Temperature Problems Volume and Temperature have a DIRECT relationship A 3.2 L sample of hydrogen gas at a temperature of 34 C is cooled to a temperature of 5 C. Calculate the new volume of the hydrogen gas. P T V n Initial
Effect X X 34 C 5 C 3.2 L x L Work: remember to convert to Kelvin by adding 273 3.2 L xL 307 K 278 K ______ ______ = 889.6= 307x x=2.9 Combined Gas Law Equations P * V P * V T T _____ _____ = The volume of a balloon is 280 mL at a pressure of 153 kPa and a temperature at 28 C. Calculate the new volume of the temperature if is raised to 32 C and the pressure changes to 176 kPa. P T V n Initial
Effect 153 kPa 28 C 280 mL 176 kPa 32 C x mL Work: 153 kPa * 280 mL 176kPa * xmL ______________ ____________ 301 K 305 K = x=144.2 mL 0 0 0 0 0 0 What is the density of the sugar? volume mass _____ Movement of Solid Particles Solids don't move a lot. Their structure is kept, but the particles are always vibrating. When hot, particles want to move faster, when cold they slow down. Movement of Liquid Particles liquid Gas Notice that liquids are free to move, but gasses are more free that liquids and tend to have more room to move.
When hot, particles move faster, more bouncing, and higher pressure.
When cold, particles slow down, less bouncing, less pressure. Energy and States Some background knowledge
thermal energy: energy stored by moving particles related to their mass and velocity
phase energy: energy stored in the system due to the arrangement of particles that exert attractions; attractions decrease the energy of particles
chemical energy: energy attractions of atoms within molecules.
caloric: heat Basics :Energy Bars 1- solid
4-gas Explanation: the diagram illustrates that a cup of coffee loses 2 bars of [th]ermal heat.
The [ph]ase has 2 bars, illustrating the coffee stays in its liquid phase. Energy Bars continued Notice that this time the water receives energy.
1 bar of energy in the phase change is added on, meaning the water receives energy.
Figure 1: The thermal is 1 bar= cold
phase is 1 bar= solid
Figure 2: The thermal is 1 bar= cold, little change
phase is 2 bars = liquid A cube of ice is left on the counter to warm. Energy Transfer Working: energy transferred between macroscopic objects
Heating: energy transferred between collisions of microscopic objects either hot to cold or vice versa.
Radiating: energy transferred through absorption or emission of photons.
(light bulb warms so much that it can emit heat) Heating Curves 0 degrees 100 degrees 0 degrees melting and freezing point
100 degrees is boiling and evaporation point ph- phase change
th- thermal change ph ph th th th Quantitative Energy Terms 334 J/g Heat fusion (melting or freezing)
amount of heat required to melt or freeze a substance.
2260 J/g Heat of vaporization (vaporization or condensing)
amount of heat absorbed to vaporize or condense a substance. Hf
Hv Heat capacity of solid or liquid water (c):
amount of heat needed to raise the temperature of a substance. 2.1 J/g C solid water
4.18 J/g C liquid water Specific Heat: How much energy it takes to raise the temperature of 1 gram to 1 C 0 0 0 Quantitative Energy problems How much energy must be absorbed by a 230 gram sample of ice at 0 degrees Celsius that melts and warms to 15 degrees Celsius? Q=mC T Q=230g(4.18J/g)(15)
Q=14,421 J 334 J/g Hf
2260 J/g Hv
2.1 J/g C solids water
4.18 J/g C liquid water Q=mHf
Q=230g (334 J/g)
Q=76,820 J This is the energy occurring during the phase change Q= 14,421+ 76,820
Q=91,241 J } Separation Techniques Magnetic attraction: separate metallic particles from non-metallic
Filtration: uses filtration paper to separate smaller particles from larger ones when diluted in water.
Evaporation: takes particles different boiling points to evaporate
Distillation: an evaporation method to get the liquid product separated from another substance through different boiling points. Element Compound Mixture 1 atom of the same kind 2 or more molecules physically separable, not
attached together chemically bonded Matter Pure substance atom molecule homogenous heterogenous uniform not uniform Water Absorbing Energy Problems Q =mC T w 375 g of water at 25 C is mixed with iron at 573 C. When it reaches thermal equilibrium, the system has a temperature of 47 C. Find the mass of the iron. The specific heat of iron is 0.45 J/g C. Q= (375 g) (4.18 J/g) (22 C)
Q=34,485 J -34,485=m(.45 J/g) (-526) -34,485=m (-236.7) ______ __________ -236.7 -236.7 m=145.69 Q begins as a negative in the second equation
subtract 573 from 47 to get -526. First find how many Jules of energy will be released #1 #2 325 mmHg = 0.43 atm Avogadro's Hypothesis If the temperature, volume, and pressure stay the same then equal amounts of particles will be present. MgCl 2 : Carbon : Molar Masses Al (SO ) : 2 4 3 12.01 g/mole Mg= 24.305
Cl (2x)= 70.9 subscript 2 = double the Cl Al (2x) = 53.96
S (3x) = 96.21
0 (12x) = 191.88 342.05 g/mole 95.21 g/mole Look at periodic table Mole Calculations How many H20 molecules are in 12.8 moles of H20? When the word "MOLECULES" appears
use 6.02 x 10 23 1 mole H20 12.8 moles of H20 __________ ______________ = 6.02 x 10 23 x Use a calculator if needed x= 7.7 x 10 24 Continued Mole Calculations What would the mass of .89 moles of CaCl be? 2 110.98 g x 1 mole .89 moles _______ _______ = Look at a periodic table, add the molar mass of Ca and 2 Cl to get 110.98 g 98.78=x ___________________________________________________________ How many moles would you have if you had 26 g of Lithium? 1 mole x 6.941g 26g ________ ______ = 3.75 = x Look at a periodic table for Lithium: 6.941g Empirical Formulas Empirical Formulas have a few more steps so watch carefully. Your answer will end up in a RATIO like this 2:1 or 1:15 and etc. Find the Empirical Formula of 7.9 g of Nitrogen and .93 g of Hydrogen. 1 mole x moles
14.01g 7.9g = ______ _______ N = x= 0.56 moles H= 1 mole x moles
1.0079g .93g ______ _______ = x= 0.92 moles N 0.56 : H 0.92 ________ ________ You want to divide by the smallest number, which will be 0.56 0.56 0.56 N=1 H= 1.6 N=1 H=2 (rounded) 1:2 Finding Percentage Composition Using the example of 7.8g of nitrogen and 0.93g of hydrogen, what is the percentage composition The total mass of the compound is 8.73g 7.8
8.73 ____ x 100 = 89% N= H= 0.93
8.73 x100= 11% ____ Conductivity Conductor: when has mobile negatively and positively charged particles.
Nonconductor: a substance that does not conduct electricity.
Ionic Compound: breaks into positive and negative charged ions
Molecular Compound: does not break down when dissolved in water, nor does it conduct electricity.
Electrolyte: compound dissolved in water that can form an electrical conducting compound. Ionic vs. Covalent vs. Metallic Bonds Ionic Covalent metals with nonmetals
gives away electrons
high melting point
Electrical Conductivity is good non-metals with non-metals
Low melting point
weak conductivity Metallic atoms move freely
high melting point
good electrical conductivity By: Vivian Naming Ionic Compounds Write the metal first
then the second element
drop the last word and add -ide to the non-metal NaCl = Sodium Chloride
BaO = H2S = Calcium Chloride Barium Oxide Hydrogen Sulfide 2 2 2 2 +1 +2 +3 +/-4 -3 -2 -1 Each column of elements contains a certain charge.
In order to pair elements, their charges must cancel each other out. Notice that
other out! Naming Ionic compounds with
Transition Metals List the metal first
List the second non-metal element
Add -ide to the non-metal
Add charges in roman numerals pertaining to the metal FeO = Iron (II) Oxide
ZnSe = 2 Manganese (II) Oxide Copper (II) Chloride Zing (II) Selenide Naming Covalent Bonds According to the subscripts, use prefixes to name the element. SiO =
P O = 3 4 10 Silicon Dioxide Nitrogen Tribromide tetraphosphorous decoxide 1-mono
10-deca Chemical Bonding Chemical Bonds: attractive force between atoms or ions that bind them in a unit
Bonds form in order to increase stability (8 electrons)
Ionic bonds: atoms give up or gain electrons and are attracted by positive/ negative charges Cation: metals that lose electrons Anions: non-metals gaining electrons Properties of Salt Hard
High melting point
non-conductive (til dissolved in water) Ionic Bonds crystal lattice
gives or gains electrons Covalent Bonds non-metals+non-metals
shares electrons Determining bonds and drawing diagrams Iron (II) Chloride =
Li ClO3= ionic bond covalent bond ionic bond ionic bond ionic bond =Li =oxygen =Cl = Polyatomic Rearranging Atoms 2 H + 1 O2 = 2 H O 2 2 2 NO + 1 O = 2NO 2 2 bond=
hydrogen= Reaction Equations and subscripts ___C + ___ H O = ___ CO + ___H 2 2 ____Al + ___HCl = ____AlCl3 + ____H 2 What we are trying to do is balance the equation.
Try and balance the amount of atoms/ molecules there are
on opposite sides of the equal sign. The first equation is already balanced on both sides
C:1 H: 2 O:1 1 1 1 1 2 6 2 3 Al :2 H:6 Cl: 6 = On each side theses values should match up Types of Chemical Reactions Synthesis Reaction:
Single Replacement Reaction:
Double Replacement Reaction:
Combustion Reaction: A + B = AB 2 Two reactants create one product AB = A + B 2K + Br = 2 KBr 2HgO= 2Hg + O 2 One reactant produces two products Examples Two reactants producing two products
one element is switched Zn + 2HCl = ZnCl +H 2 2 A+BC= AC+B AB+CD=AD+CB Two reactants produce two products
compounds are switched
no elements all compounds AgNO + KCl = AgCl +KNO 3 3 All non-metals ( C, H, O)
reactant is O2 2C OH + 6 O = 6CO + H O 3 2 2 2 Background on Chemical Reactions Conservation of Mass:
Subscripts in Formulas:
Coefficient: matter cannot be created or destroyed. a representation of chemicals using symbols: subscripts and coefficients how many atoms 1 molecule needs how many molecules needed All of the atoms are accounted for, none are lost. They must be used up. Two molecules of Al This is a subscript: it tells you how many atoms are present. Right now there are 2 H atoms and 3 molecules of hydrogen. this is a subscript, 3 atoms of Cl.
2 molecules of AlCl3. These subscripts take into account of the molar mass when calculating moles. Al= 26.98 Cl= 35.45 (x3) = 133.33 grams With word Equations Bromine reacts with sodium iodide to form sodium bromide and iodine. Br + NaI = NaBr + I Single replacement
switched up one product A+BC=AC+B Propane, C H , burns in air to produce carbon dioxide and water. 3 8 5 O + C H = 3CO + 4H O 2 3 8 2 2 Combustion
All gasses, no metals Phosphorous (P ) reacts with bromine to produce phosphorous tribromide. 4 1 P + 6Br = 4PBr 4 2 3 Synthesis
2 reactants form 1 product A+B = AB Get Stoiched! Ammonia, NH , for fertilizer is made by causing hydrogen and nitrogen to react at high at high temperature and pressure. How many moles of ammonia can be made from 0.15 moles of nitrogen gas. 3 ____H2 + ____N2 = ____NH3 First Write out the Equation Balance the Equation Before:
After: 3 1 2 Put the # of moles into your BCA table 0.15 xs -0.15 0 moles -0.45 xs 0 +0.3 0.3 0.3 moles Double or triple value depending on coefficient Assume there is zero of the product assume you have enough of reactant Stoichiometry Moles-Mass "This will be a piece of cake!"
:P If 89 grams of copper react with mercuric nitrate, how many grams of mercury form? Cu + Hg(NO3) = Cu(NO3) +Hg 2 2 Before:
After: 1 x ____ ____ 63.546g 89g = this is the molar mass
of Copper from the periodic table together. x= 1.4 put this into your BCA table 1.4 xs -1.4 0 -1.4 xs 0 0 +1.4 +1.4 1.4 1.4 1.4moles 1moles ________ ________ x 200.59g = x= 280.826g Stoichiometry Moles-masses Calculate the number of molecules of oxygen required to react with 75 grams of aluminum. Before:
After: 4 Al + 3 O = 2 Al O 2 3 2 1 x _____ _____ 26.98g 75g x=2.78 2.78 -2.78 xs -2.08 0 +1.39 0 xs 1.39 molecule= 6.02 x 10 23 2.08 x 6.02 = 12.643 x 10 28 Answer: = Determining Moles- Masses How many grams of sulfer are required in the preparation of 800 grams of sulfur dioxide? S + O2 = SO2 1mole x mole _____ _____ 64.1g 800g = x= 12.48 12.48moles 1moles x= 400 grams ___________ ______ x g 32.066g = If you preferred to do a BCA chart, all would have 12.48 moles, so in the end there will be 12.48 moles of sulfur used in the reaction. Then you would set up your equation (upper right) Percent Yield Suppose 4.61 g of zinc was allowed to react with hydrochloric acid to produce zinc chloride and hydrogen gas. How much zinc chloride should you get? Suppose that you actually get 8.56 of zinc chloride. What is the percent yield? Zn + 2HCl = ZnCl + H 2 2 Before:
After: 4.61g 65.39g ______ ______ x moles 1 mole = x= .07 .07 -.07 0 xs -.14 xs 0 0 +.07 .07 +.07 .07 .07 moles 1 mole _______ _______ x g 136.30 g = x= 9.54 (This is your theoretical yield.) Actual ______ Theoretical 8.56 g _____ 9.54g = 89.9 % Percent yield Limiting Reactant A 14.6 gram sample of oxygen gas is placed in a sealed container with 2.5 grams of hydrogen gas. The mixture is sparked, producing water vapor. Calculate the mass of water formed. Calculate the number of moles of the excess reactant remaining. 2H + O = 2H O 2 2 2 Before:
After: O= 14.5 g 32g _____ _____ x mole 1mole = H= 2.5 g 2g ________ ________ x moles 1 mole = x= 0.46 moles x= 1.25 moles 1.25 0.46 0 -.192 -0.46 +.192 0.338 0 .192 .192moles 1mole __________ _______ x g 18 = x= 16.416g (this is the moles of excess reactant remaining) O2 is the limiting reactant since there isn't enough of it completely carry out the reaction. (Double the H20 values since they have coefficients of 2) First subtract 0.46 since that is the smallest value, most likely will become the limiting reactant. Note that when balancing this equation. H must have a subscript of 2 since it is a Diatomic Element. All diatomic elements have a subscript 2. How to use a BCA table... B C A efore hange fter Before:
After: 2 Al + 3 I = 2Al I 2 3 Put mole calculations into the BCA chart before what are your values when the reaction takes place what is being added, subtracted, neutralized... final result of how many moles Gas Law Stoichiometry at Standard Conditions What volume of Na SO gas can be formed from 745 g of sodium chloride at standard conditions? 2 4 4NaCl+ 2SO + 2 H O + O = 2Na SO +4HCl 2 2 2 2 4 B:
A: 1 mole x mole 58.4g 745g ______ ______ = x=12.75 moles 12.75 -12.75 +12.75 xs xs xs -6.375 +6.318 0 0 0 xs xs xs 6.318 12.75 6.318moles 1mole __________ _____ xL 22.4 L = x=141.52 L Dilution The comparison a less concentrated solution to a more concentrated solution = dilution M x V = M x V 1 1 2 2 Before After ex. What volume of 12.1 M hydrochloric acid is needed to make 3.0 L of 1.0 M HCl? 3 L x 1M = 12.1M x X L x= 0.25 L Solvation Process of surrounding solute particles with solvent particles to form solution.
Dissociation: when ions separate Factors affecting
Rate of Dissolving: Temperature Particles size Mixing Amount Degree of Solubility: 1.)saturation solution
3.)supersaturated solution positive ions attracted to negative ions in a specific structure Intermolecular Forces: ion-ion
hydrogen bonding solution: homogenous mixture
solute: "thing" being dissolved
solvent:present in greater amounts "dissolves solute
soluble: "will dissolve in"
miscible: refers to TWO GASSES or TWO LIQUIDS that form a solution
insoluble: "will not dissolve in"
immiscible: Two gasses or liquids will not form a solution
suspension: seems to appear uniform but settles over time
colloid: looks like a solution but small particles will cause a "Tyndall" effect. Solubility Curves How many grams of solute are required to saturate 100 g of water in the following. KCl at 80 C _________ KCl at 70 C _________ NaNO3 at 10 C ________ In 100 grams of water are the following solution saturated, unsaturated, or supersaturated? 40 g of NaCl at 50 C ____________ 51g 49 g 80g supersaturated 300 ml of 2.5 M of Nitric Acid is added to 500 ml of water, what is the molarity of the dilute solution? 2.5 M x 300ml = X M x 800L x= 0.9375 M Density Problems wood measures 3 cm x 6 cm x 4 cm
mass: 80 grams
density = x Volume = 72 cm cubed 80 g _____ 72 cm = 1.11g/ml the density of water is 1.0.
Is the wood's density greater than that of water? YES, it would sink So... if you got this far Now you'll know... Why....