-Equal volumes of different gases had a constant ratio
Relative Mass
-expressed by comparing it mathematically to the mass of another object
Avogadro's hypothesis
-equal volumes of different gases at the same temperature and pressure have the same unmber of particle
-if they have same number of particles, the mass tatio is due to the mass of particle
FORMULA MASS
-total mass of all the atoms in he formula of an ionic compound in atomic mass units
K39.1u+F19.0u =KF58.1u
MOLECULARR MASS
-total mass of all the atoms that make up a molecule of a covalent compound organic compound or a polyyatomic element in atomic mass units
canbon dioxide
C 12.0g+O2 32g=44g
MOLAR MASS
mass of 1 mole of substane and is the same numerical value of atomic mass, formula mass, or molecular mass but expressed in Grams Per Mole
-1mole of oxygen=16.0g/mol
-1mole of carbon=12.0g/mole
the molar atomic mass of an element is the mass of 1 mole that element
the units of molar are grams per mole (g/mole)
Avogadro's number
-the number of particles in 1 mole of any amount of substance
6.022*10 to the 23
-the mole is extremely important to chemists because it allows them to sount atoms and molecules
2010年11月25日星期四
mole conversions
1. A)conversions from paricles---mole
Ex: 3.01 x 10^24----particles/moles
3.01 x 10^24particles x 1mole/6.022 x 10^23particels =5.00moles
B)moles---particles
0.75moles CO2---molecules
0.75moles x 6.022 x 10^23molecules/1mol = 4.5 x 10^23molecules of CO2
C)0.75moles CO2---atom of oxygen
4.5 x 10^23molecules CO2 x 2atoms/1molecules CO2 = 9.0 x 10^23 atoms of oxygen
2.A) conversions from moles----grams
2.04moles C---grams
molar mass of C---12g/mole
2.04moles x 12g/mole = 24.5g of C
B)grams---moles
3.45g C ---moles
3.45g x 1mole/12.0g = 0.288moles
----------------------------------------------------------------------------------------------------------
Ex: 3.01 x 10^24----particles/moles
3.01 x 10^24particles x 1mole/6.022 x 10^23particels =5.00moles
B)moles---particles
0.75moles CO2---molecules
0.75moles x 6.022 x 10^23molecules/1mol = 4.5 x 10^23molecules of CO2
C)0.75moles CO2---atom of oxygen
4.5 x 10^23molecules CO2 x 2atoms/1molecules CO2 = 9.0 x 10^23 atoms of oxygen
2.A) conversions from moles----grams
2.04moles C---grams
molar mass of C---12g/mole
2.04moles x 12g/mole = 24.5g of C
B)grams---moles
3.45g C ---moles
3.45g x 1mole/12.0g = 0.288moles
----------------------------------------------------------------------------------
3 A) particles --mass
2.78 x 10^22 Fe atoms x 1mole/6.022 x 10^23 x 55.8g/1mole = 2.58 g
B)mass- particles
20.0g Fe x 1mole/55.8g x 6.022 x 10^23particles/1mole = 2.16 x 10^23particle
----------------------------------------------------------------------------------------------------------
2010年11月8日星期一
2010年11月2日星期二
Accuracy & Precision
-Precision: how reproducible a measurement is compared to other measurement
-Accuracy: how close the measurement for average measurement comes to the accepted or real value
Measurement and Uncertainty
-no measurement is exact
-every measurement is a best estimate
-countable number is exact number
Absolute Uncertainty
-expressed in units of measurement, not as a ratio
Method1:
-make at least 3 measurement, calculate the average
-the absolute uncertainty is the largest difference between the average and the lowest and highest.
Ex:
1 15.3g average: 15.3g
2 15.5g AU: 15.3 ± 0.2g
3 15.2g
4 11.9g(remove)
5 15.3g
Method2:
determine the uncertainty of each instrument.
always measure to the best precision that you can.
Relative Uncertainty & Significant Figure
RU=AU/estimate uncertainty Ex: 39.3±0.1g RU = 0.1/39.3×100%
or using Sig Fig: the last number in the measurement is uncertain
-Accuracy: how close the measurement for average measurement comes to the accepted or real value
Measurement and Uncertainty
-no measurement is exact
-every measurement is a best estimate
-countable number is exact number
Absolute Uncertainty
-expressed in units of measurement, not as a ratio
Method1:
-make at least 3 measurement, calculate the average
-the absolute uncertainty is the largest difference between the average and the lowest and highest.
Ex:
1 15.3g average: 15.3g
2 15.5g AU: 15.3 ± 0.2g
3 15.2g
4 11.9g(remove)
5 15.3g
Method2:
determine the uncertainty of each instrument.
always measure to the best precision that you can.
Relative Uncertainty & Significant Figure
RU=AU/estimate uncertainty Ex: 39.3±0.1g RU = 0.1/39.3×100%
or using Sig Fig: the last number in the measurement is uncertain
2010年11月1日星期一
Significant Figure
-How to wirite the math anseers correctly-
Signifcant Digit
-the last number is uncertain
-E.g.---2.56 2.5(certain) 6(uncertain)
-wirte only one uncertain digits
Detail
-leading zero aren't counted
0.0000001 has 1 sig fig
-zero after decimal are counted
10050 has 5 sig fig
-trailing without decimal point aren't counted
12000000 has 2 sig fig
Exact number
-some quantities are defined as exactly a certain and no rounding require
Rounding Rules
-round the answers of digits using rules similar to math
-Digit > 5 round up
62.47---62.5
62.43---62.4
62.45000003---62.5
62.4585---62.5
Signifcant Digit
-the last number is uncertain
-E.g.---2.56 2.5(certain) 6(uncertain)
-wirte only one uncertain digits
Detail
-leading zero aren't counted
0.0000001 has 1 sig fig
-zero after decimal are counted
10050 has 5 sig fig
-trailing without decimal point aren't counted
12000000 has 2 sig fig
Exact number
-some quantities are defined as exactly a certain and no rounding require
Rounding Rules
-round the answers of digits using rules similar to math
-Digit > 5 round up
62.47---62.5
62.43---62.4
62.45000003---62.5
62.4585---62.5
2010年10月18日星期一
Naming Acid
-Acid tastes sour
-has a pH less than 7.0 in its standard state
-the fomula of acid begins with H
-has a pH less than 7.0 in its standard state
-the fomula of acid begins with H
REMINDER
--use H as the begining
--the postfix replace with "-ic"
--add "acid" at the end
*-ide---hydro_____ic acid
Simple Acid
Ex:
1.HF--hydroflouric acid
2.HCl--hydrochloric acid
3.HI--hydroiodic acid
4.H2O--water--hydroxide acid
Naming Complex Acid
* -ate --- -ic
-ite --- -ous
Ex:
1.HCH3COO---Acetic acid
2.HClO3---Chloric acid
3.H2SO4--Sulphuric acid
2010年10月12日星期二
ionic&covalent compounds
----- Ionic Compounds
1.composed of 2 or more particles (oppositely charges)
2.held together by electrostatics forming
3.electrons are transferred from a metal ---non metal
Ex
AgI--Silver(metal) Iodide(non metal)
Li2O--Lithium(metal)Oxide(non metal)
Lead(II) nitrate--Pb(NO3)2
Complex Anions: a group of atoms that behave as are atom
Na2SO4---Sodium Sulphate
Calcium Hydroxide---Ca(OH)2
------------------------------------------------------------------------------------------------
----Covalent Compounds
-share electrons
-non metal+ non metal
*diatomic molecules: H O F Br N Cl I
-use Greeks prefixes to indicate the number of atoms
1mono 2di 3tri 4tetra 5penta 6hexa 7hepta 8octa 9nona 10deca
Ex CO2--Carbon dioxide
N2O--Dinitrogen monoxide
2010年10月4日星期一
Matter is Made of Atom2.7--2.9
-Up to this point you have made observations by what you can see, feel,or smell. such observations are macroscopic observations
-Melting point, boiling point, heat of fusion, temperature, and mass are all properties of large chunks of matter and are called macroscopic properties
-A microscopic model (micro is a prefix meaning small; when used with SI units, it means 1Million) to explain the behavior of matter.
2-7: Atom
-Small particles like atoms and molecules are discussed int he popular literature as though they were as common as toads and warts.
-the original idea of atoms was developed long before as a kind of armchair argument.
-Atom: the smallest possible piece of something
-Chemists use spheres to help them imagine what is happening in the microscopic world.
2-8: Element
-more than one kind were present, it should be possible to separate the two kinds of atoms, producing different substances with different properties.
-there are as many kinds of atoms as there are elements, 109.
-an element can exist as solid, liquid or gas.
-most elements seem to exist as individual atoms , but some elements exist as larger units
-Particles made of more than one atom are called molecules.
-There is no simple way to tell which elements exist as individual atoms in a gas and which exist as larger clusters of atoms
-
2-9: Compounds
-all compounds must be made of two or more kinds of atoms
-Molecules have definite shapes as well as definite composition, but you do not have to worry about why until later.
-since compounds are made of two or more kinds of atoms, the different atoms can be separated if enough energy is supplied to break the compound apart.
-heat and electricity are forms of energy and both heating and electrolysis can supply the energy needed to decompose the compound
-not all compounds are made of molecules. Sodium chloride melts to form positively charged sodium ions and negatively charged chloride ions.
-Ions: are particles that have and electrical charge.
-the only way to know which compounds are ionic and which compounds are molecular is to check them for conductivity
-Melting point, boiling point, heat of fusion, temperature, and mass are all properties of large chunks of matter and are called macroscopic properties
-A microscopic model (micro is a prefix meaning small; when used with SI units, it means 1Million) to explain the behavior of matter.
2-7: Atom
-Small particles like atoms and molecules are discussed int he popular literature as though they were as common as toads and warts.
-the original idea of atoms was developed long before as a kind of armchair argument.
-Atom: the smallest possible piece of something
-Chemists use spheres to help them imagine what is happening in the microscopic world.
2-8: Element
-more than one kind were present, it should be possible to separate the two kinds of atoms, producing different substances with different properties.
-there are as many kinds of atoms as there are elements, 109.
-an element can exist as solid, liquid or gas.
-most elements seem to exist as individual atoms , but some elements exist as larger units
-Particles made of more than one atom are called molecules.
-There is no simple way to tell which elements exist as individual atoms in a gas and which exist as larger clusters of atoms
-
2-9: Compounds
-all compounds must be made of two or more kinds of atoms
-Molecules have definite shapes as well as definite composition, but you do not have to worry about why until later.
-since compounds are made of two or more kinds of atoms, the different atoms can be separated if enough energy is supplied to break the compound apart.
-heat and electricity are forms of energy and both heating and electrolysis can supply the energy needed to decompose the compound
-not all compounds are made of molecules. Sodium chloride melts to form positively charged sodium ions and negatively charged chloride ions.
-Ions: are particles that have and electrical charge.
-the only way to know which compounds are ionic and which compounds are molecular is to check them for conductivity
2010年10月3日星期日
Finding Out about Matter2.1-2.6
2-1:What You Know about Matter
-water is one of the most familiar kinds of matter.
-water samples collect from a muddy stream and the ocean are different
-they dont look the same,taste the same, or boil at the same temperature, and different densities
-the temperature at which matter changes from a liquid to a gas, its boiling point, is still another property that you use to identify matter.
2-2:Purifying Matter
-Mixture---two or more kinds of matter that have separate identities.
-Matter that is easily separated into component parts is called a mixture or said to be impure.
-Mixtures like salt water or sugar water that look uniform throughout and do not scatter light are called solutions
-Mixtures are matter that can be separated into component parts that have a separate identity
-Distillation is a method of separating mixtures based on differences in their volatilities in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction.
-Many mixtures are extremely difficult to separate. Much of the recent awareness of air pollution, water pollution, carcinogens in foods, and similar environmental concerns have come about because new and better techniques have been found to detect those impurities.
2-3:Characteristics of Pure Substances
-Characteristics of Mixture: if you boil the water collected in this way, you will find that the temperature will remain constant from the time the water first boils until it all disappears.
-Characteristics of Pure Substances: have a constant boiling point; mixtures ordinarily do not
-but a few have a constant boiling point, because the water and grain alcohol cannot be separated by distillation is that a mixture containing 95.6% ethanol and 4.4% water has a constant boiling point of 78.2℃
-the temperature at which a liquid changes o a solid is called its freezing point(melting point), the temperature at which a solid becomes a liquid.
2-4: Chemical and Physical Change
-Density is a property of matte that describes its mass per unit volume.
-Changes that produce a new kind of matter with different properties are called chemical changes. This particular chemical change is called a decomposition because one kind of matter comes apart(decomposes) to form two or more kinds of matter.
-melting is therm used to describe the change of a solid to a liquid without the formation of any new kind of matter
-Change that didnt produce new kinds of matter and reversible are called Physical changes. Boiling is a physical change
2-5:Compounds and Elements
-Ex: when salt is melted and an electric current is passed through the melt ,the salt decomposes to form sodium metal at the negative electrode and chlorine gas at the positive electrode. The process just described is called electrolysis. Electrolysis involves passing an electric current through a substance, causing into decompose into new kinds of matter.
-Decomposition of a pure substance and distillation of a mixture are both processes in which matter is separated into components, but in thinking about what happens you see that they are fundamentally different processes
-In decomposition, a single , pure substance with constant, characteristic properties is somehow changed into new substances with different properties. Decomposition represents a chemical change
-Pure substances that can be decomposed into new kinds of matter are called compounds
-the elements building blocks of all kinds of matter and are called elements
-109 known elements
-Virtually all matter on Earth is made of obly 85 elements, and just eight of these account for 99% of the Earthe's crust. All other elements in Earth's crust make up ony 1% of its mass
2-6: Compounds Have a Definite Compositon
-not all combinations of elements are compounds.
-The law of definite composition states that all samples of a compound have the same composition— the same proportions by mass of the constituent elements.
-The law of multiple proportions states that when two elements combine to form two or more compounds, the mass of one element that combines with a given mass of the other is in the ratio of small whole numbers
-CHEM THEME:Any sample of a given compound contains the same percentage by mass of each element. Samples of compounds which contain the same elements but in different percentages by mass are defferent.
-water is one of the most familiar kinds of matter.
-water samples collect from a muddy stream and the ocean are different
-they dont look the same,taste the same, or boil at the same temperature, and different densities
-the temperature at which matter changes from a liquid to a gas, its boiling point, is still another property that you use to identify matter.
2-2:Purifying Matter
-Mixture---two or more kinds of matter that have separate identities.
-Matter that is easily separated into component parts is called a mixture or said to be impure.
-Mixtures like salt water or sugar water that look uniform throughout and do not scatter light are called solutions
-Mixtures are matter that can be separated into component parts that have a separate identity
-Distillation is a method of separating mixtures based on differences in their volatilities in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction.
-Many mixtures are extremely difficult to separate. Much of the recent awareness of air pollution, water pollution, carcinogens in foods, and similar environmental concerns have come about because new and better techniques have been found to detect those impurities.
2-3:Characteristics of Pure Substances
-Characteristics of Mixture: if you boil the water collected in this way, you will find that the temperature will remain constant from the time the water first boils until it all disappears.
-Characteristics of Pure Substances: have a constant boiling point; mixtures ordinarily do not
-but a few have a constant boiling point, because the water and grain alcohol cannot be separated by distillation is that a mixture containing 95.6% ethanol and 4.4% water has a constant boiling point of 78.2℃
-the temperature at which a liquid changes o a solid is called its freezing point(melting point), the temperature at which a solid becomes a liquid.
2-4: Chemical and Physical Change
-Density is a property of matte that describes its mass per unit volume.
-Changes that produce a new kind of matter with different properties are called chemical changes. This particular chemical change is called a decomposition because one kind of matter comes apart(decomposes) to form two or more kinds of matter.
-melting is therm used to describe the change of a solid to a liquid without the formation of any new kind of matter
-Change that didnt produce new kinds of matter and reversible are called Physical changes. Boiling is a physical change
2-5:Compounds and Elements
-Ex: when salt is melted and an electric current is passed through the melt ,the salt decomposes to form sodium metal at the negative electrode and chlorine gas at the positive electrode. The process just described is called electrolysis. Electrolysis involves passing an electric current through a substance, causing into decompose into new kinds of matter.
-Decomposition of a pure substance and distillation of a mixture are both processes in which matter is separated into components, but in thinking about what happens you see that they are fundamentally different processes
-In decomposition, a single , pure substance with constant, characteristic properties is somehow changed into new substances with different properties. Decomposition represents a chemical change
-Pure substances that can be decomposed into new kinds of matter are called compounds
-the elements building blocks of all kinds of matter and are called elements
-109 known elements
-Virtually all matter on Earth is made of obly 85 elements, and just eight of these account for 99% of the Earthe's crust. All other elements in Earth's crust make up ony 1% of its mass
2-6: Compounds Have a Definite Compositon
-not all combinations of elements are compounds.
-The law of definite composition states that all samples of a compound have the same composition— the same proportions by mass of the constituent elements.
-The law of multiple proportions states that when two elements combine to form two or more compounds, the mass of one element that combines with a given mass of the other is in the ratio of small whole numbers
-CHEM THEME:Any sample of a given compound contains the same percentage by mass of each element. Samples of compounds which contain the same elements but in different percentages by mass are defferent.
2010年9月27日星期一
Matter
What is matter?
-Anything that has mass and takes up space
MATTER
proporties of matters
Three states:
- Solid: dont change shape easilyexperiences small change in volume when heated
- Liquid: takes the shape in the container and experience
- gases: takes the shape of the container and experiences drastic in volumn when heated
-Pure Substance
-one set of proporties
-one kind of particle
/ \
element compound
- (cannot -made of element
be elecomposd) -chemically combined
-made of atom -smallest particle is molecule
/ \ / \
metal non-metal Ionic covalent
-Mixture
-more than on set of proporties and substances
-physically combined
/ \
homogeneous heterogeneous
-uniform throughour -not uniform
-appears to have only -appears to have more than one components
one component Example: water+oil
Example: Solution
Physical Change Chemical Change
-no new substance is formed -new substance is produced
-chemical composition doesnt change -irreversible
-reversible
Example:meliting / boiling point Example:buring+cooking+rotting
-Anything that has mass and takes up space
MATTER
proporties of matters
Three states:
- Solid: dont change shape easilyexperiences small change in volume when heated
- Liquid: takes the shape in the container and experience
- gases: takes the shape of the container and experiences drastic in volumn when heated
-Pure Substance
-one set of proporties
-one kind of particle
/ \
element compound
- (cannot -made of element
be elecomposd) -chemically combined
-made of atom -smallest particle is molecule
/ \ / \
metal non-metal Ionic covalent
-Mixture
-more than on set of proporties and substances
-physically combined
/ \
homogeneous heterogeneous
-uniform throughour -not uniform
-appears to have only -appears to have more than one components
one component Example: water+oil
Example: Solution
Physical Change Chemical Change
-no new substance is formed -new substance is produced
-chemical composition doesnt change -irreversible
-reversible
Example:meliting / boiling point Example:buring+cooking+rotting
2010年9月21日星期二
Scientific Notation&Evaluation
Scientif notation=Exponential notation
8
Evaluate:
- is used to express very large or small numbers to be convinient.
- In scientif notation, all numbers are written like this: a × 10b ((1 ≤ |a| < 10))
Ex: Express in scientific form:
Ex: Express in standward form:E notation:
Most calculators and many computer programs present very large and very small results in scientific notation. Because superscripted exponents like 107 cannot always be conveniently represented on computers, typewriters and calculators, an alternative format is often used: the letter E or e represents times ten raised to the power of, thus replacing the × 10, followed by the value of the exponent.
Calculator:
Ex: 2.5---->Exp8----
Ex: 2.5---->Exp8----
----> Ee8
8Evaluate:
Even more unitary rates: If
Ex: Convert:
A:
B:
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