Download Chapter 3. Formulas, Equations and Moles 3.1 Balancing chemical

Chapter 3. Formulas, Equations and Moles
3.1 Balancing Chemical Equations
3.2 Chemical Symbols and Different Levels
3.3 Avogadro s Number and the Mole
STOICHIOMETRY
3.4 Stoichiometry: Chemical Arithmetic
3.5 Yields of Chemical Reactions
3.6 Reactions with Limiting Amounts of Reactants
CHEMICAL REACTIONS IN SOLUTION
3.7 Concentrations of Reactants in Solution: Molarity
3.8 Diluting Concentrated Solutions
3.9 Solution Stoichiometry
3.10 Titration
ELEMENTAL ANALYSIS
3.11 Percent Composition and Empirical Formulas
3.12 Determining Empirical Formulas: Elemental Analysis
3.13 Determining Molecular Masses: Mass Spectrometry
3.1 Balancing chemical equations
The following chemical equation is said to be mass balanced :
2Na + Cl2
reactants
2 NaCl
products
The numbers and types of atoms on both sides are the same.
Balancing is a 4 step process. A mix of trial/ error and common sense.
1. Write down the unbalanced equation using the correct chemical
formula for all compounds.
2. Use coefficients (the # placed before the formula) to indicate how
many formula units are required to balance LS with RS.{Hint: It
helps to balance oxygen last}
3. If necessary, reduce the value of all coefficients to their smallest
whole- number values.
4. Verify that it is balanced.
1
Write a balanced equation for the combustion of C5H12 with O2
producing water and carbon dioxide
Step 1:
Write the unbalanced equation
C5H12 + O2
CO2 + H2O
Step 2: Use coefficients to balance. Lets begin with carbon.
5 carbons on LS ; therefore place 5 in front of CO2 on RS.
C5H12 + O2
5 CO2 + H2O
12 hydrogens on LS:
Place a 6 in front of H2O on RS.
C5H12 + O2
5 CO2 + 6 H2O
Now balance oxygens. (5 x 2) + (6 x 1) or 16 oxygens on RS.
Place an 8 in front of O2 on LS.
C5H12 + 8 O2
5 CO2 + 6 H2O
Step 3: Reduce the coefficients to their smallest whole number- ratio
the ratio 1:8:5: 6 is the smallest ratio.
Step 4: Check your answer
Balance the following equation:
KClO3 + C12H22O11
Ans: 8 KClO3 + C12H22O11
3.2
8 KCl
KCl
+ CO2 + H2O
+ 12 CO2 + 11 H2O
Chemical Symbols at Different levels
Chemical symbols represent both a microscopic and macroscopic
level.
Microscopic level- chemical formulas represent the behavior
of (a few) atoms and molecules.
Macroscopic level- Chemical formulas and chemical equation
now represent the large- scale ( gram scale) behavior of atoms
and molecules that give rise to observable properties.
2
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