The following topics are covered in this booklet;
Significant Figures
Temperature
Mass
Volume
Density Calculations
Naming Ionic Compounds
Writing Ionic Formulae
Empirical and Molecular Formula
Balancing Chemical Equations
Writing Equations: Precipitation Reactions
Percent Composition (Percentage Composition)
Definitions of a mole
Mass-Mole Calculations (n = mass ÷ MM)
Concentration of Solutions Calculations (M = n ÷ V)
Dilution of Solutions Calculations (M1V1=M2V2)
Reaction Calculations: Mass and Moles
Limiting Reagents & Reactants in Excess
Yield
 
Significant Figures
Key Concepts
Scientific notation, or exponential notation, is a convenient way to write down a very large or a very small number.
In scientific notation each number is written as a product of two numbers:
a coefficient x 10an exponent
Coefficients are usually expressed with one digit to the left of the decimal point.
An exponent gives the position of the decimal point in the number and is either: 
    positive (generally for numbers greater than or equal to 10) 
    zero (generally for numbers between 0 and 10) 
    negative (generally for numbers less than 0)
Converting a Number to Scientific (exponential) Notation
Write 0.015 in scientific (exponential) notation.
Step1, write the coefficient : 1.5
Step 2, count the places between the current decimal place and its position in the coefficient: 2
Step 3, determine the sign of the exponent. Moving to the right gives a negative sign (the number is less than 0): -
Finally write the number in scientific notation: 1.5 x 10-2
Write 256.35 in scientific (exponential) notation.
Step1, write the coefficient : 2.5635
Step 2, count the places between the current decimal place and its position in the coefficient: 2
Step 3, determine the sign of the exponent. Moving to the left gives a positive sign (the number is greater than 10): +
Finally write the number in scientific notation: 2.5635 x 10+2 which is usually written as 2.5635 x 102
Write 42.76 in scientific (exponential) notation.
Step1, write the coefficient : 4.276
Step 2, count the places between the current decimal place and its position in the coefficient: 1
Step 3, determine the sign of the exponent. Moving to the left gives a positive sign (the number is greater than 10): +
Finally write the number in scientific notation: 4.276 x 101
Write the number 3.56 in scientific (exponential) notation.
Step1, write the coefficient : 3.56
Step 2, count the places between the current decimal place and its position in the coefficient: 0
Zero is neither positive nor negative in sign.
Finally write the number in scientific notation: 3.56 x 100
Converting Scientific (exponential) Notation to a Decimal System Number
Write 1.23 x 103 as a decimal system number.
Step1, decide which way the decimal point will move based on whether the exponent is positive (move to right) or negative (move to left) : + therefore moves to right (number is greater than 10)
Step 2, decide how many places the decimal point will move based on the size of the exponent: 3 places
Finally write the number using zeroes to fill in the places between the decimal point in the coefficient and in the new number: 1230
Write 4.76 x 10-2 as a decimal system number.
Step1, decide which way the decimal point will move based on whether the exponent is positive (move to right) or negative (move to left) : - therefore moves to left (number is less than 0)
Step 2, decide how many places the decimal point will move based on the size of the exponent: 2 places
Finally write the number using zeroes to fill in the places between the decimal point in the coefficient and in the new number : 0.0467
Write 5.22 x 101 as a decimal system number.
Step1, decide which way the decimal point will move based on whether the exponent is positive (move to right) or negative (move to left) : + therefore moves to right (number is greater than 10)
Step 2, decide how many places the decimal point will move based on the size of the exponent: 1 place
Finally write the number using zeroes to fill in the places between the decimal point in the coefficient and in the new number if necessary: 52.2
 
Temperature
Key Concepts
Temperature is a measure of the average kinetic energy of the particles in an object. 
    Adding energy, eg, heat, to an object increases the kinetic energy of the particles which is observed as an increase in temperature. 
    When an object loses energy, kinetic energy of the particles decreases and is observed as a decrease in temperature.
Several temperature scales are in common use: 
    Kelvin Scale based on the kelvin unit (K), the SI unit of temperature. 
    Celsius Scale based on degrees Celsius (oC), closely related to the Centigrade scale. 
    Fahrenheit Scale based on degrees Fahrenheit (oF), commonly used in North America.
Kelvin Scale is based on the following fixed points: 
    The zero point is absolute zero, the lowest temperature theoretically obtainable. 
    The temperature at which solid, liquid and gaseous water can coexist indefinitely (the triple-point tempera-ture of water) is assigned a value of 273.16K
Celsius Scale is based on a triple-point temperature of water of 0.01oC, and at 1atm pressure a freezing point of 0.00oC and a boiling point of 100.00oC. 
    Celsius units (oC) are the same size as kelvin units (K).
Fahrenheit Scale is based on a freezing point of water of 32oF and a boiling point of 212oF.
Temperature Conversions
Converting Celsius (oC) to kelvin (K)
kelvin (K) = oC + 273.15
Converting kelvin (K) to Celsius (oC)
oC = K - 273.15
Converting Fahrenheit (oF) to Celsius (oC)
oC = 5/9 x (oF - 32)
Converting Celsius (oC) to Fahrenheit (oF)
oF = (9/5 x oC) + 32
Examples of Temperature Conversions
Convert 100oC to kelvin
kelvin (K) = oC + 273.15
K = 100 + 273.15 = 373.15K
Convert 298.15K to Celsius
oC = K - 273.15
oC = 298.15 - 273.15 = 25oC
Convert 212oF to Celsius
oC = 5/9 x (oF - 32)
oC = 5/9 x (212 - 32) = 100oC
Convert 30oC to Fahrenheit
oF = (9/5 x oC) + 32
oF = (9/5 x 30) + 32 = 86oF
Convert 80oF to kelvin
Convert oF to oC 
oC = 5/9 x (oF - 32) 
oC = 5/9 x (80 - 32) = 26.67oC
Convert oC to K 
K = oC + 273.15 
K = 26.67 + 273.15 = 299.82K
Convert 293.15K to Fahrenheit
Convert K to oC 
oC = K - 273.15 
oC = 293.15 - 273.15 = 20oC
Convert oC to oF 
oF = (9/5 x oC) + 32 
oF = (9/5 x 20) + 32 = 68oF
 
Mass
Key Concepts
Mass is a direct measure of the amount of matter in an object.
The SI unit of mass is the kilogram which is given the symbol kg .
Chemists in a laboratory usually deal with much smaller masses than kilograms, often grams or milligrams, so we need to be able to convert from one unit of mass to another.
 

CHEM109 Chemistry Fundamentals

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