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*Unit 8 Topics
Aldehydes and Ketones
Alkenes and Alkynes
Amines and Amides
An overview of molarity problem
Atomic Mass and Avogadro's Hypothesis
atomic number and mass
Balancing Chemical Reaction Equations
Basic Science definitions.
Calculations involving the Mole and the Mass of a Substance and the Volume of a gas
Calculations involving the Mole and the Volume of a gas and the Number of Particles
Certain & Uncertain Digits, Defined Numbers and Accuracy & Precision
Chemical Equations and the Conservation Laws
Chemical families -- by Judy Bai
Classification of matter
Concentration of ions in Solution
Constructing the name of an Ionic Compound
Derived Quantities and Density
Early atomic models
Electrostatic forces, electron shells, Valence electrons and valence of an atom
Energy Changes in Chemical Reactions
Ethers and Carboxylic Acids
History of the period table
How to Classify Atoms and Ions
How to Read a Scale
INTERMOLECULAR FORCES AND BONDING
Introduction to functional groups and Alcohols---Elizabeth
Introduction to organic chemistry and hydrocarbon
Ionization energy, Electron Affinity, Atomic Radius
Isotopes and their mixtures
Lab safety 2
Later atomic models
Lewis Dot Diagrams of Neutral Atoms, Monatomic Ions,and Ionic Compounds
LIine spectra, electron shells and energy level diagrams
Mixing Two Solutions and Making Dilute Solutions
Molar Concentrations and Making up Solutions
Multiple conversions between moles,mass, volume and number of particles
Multiplying & Dividing and Adding and Subtracting with Sig Figs
Naming Hydrates and Naming Compounds Using the Prefix System
Naming Monatomic and Polyatomic Ions
Percent Yield and Purity
Phase Changes--by AnnYU
Phases, the Magic 7 and Chemical Word Equation
polar and nonpolar solvents
SI Units and Metric Unit conversions
Significant Figures & Zeros
Solutions and Solubility Introduction
Solving Problems that Involve Multiple Operations and Sig Figs
Stoichiometery calculation involvingMoles, Mass, Gas volume and Molecules
Stoichiometry Calculations Involving Molar Concentration
Stoichiometry of Excess Quantities
The Conductivity of Aqueous solutions
The Major divisions of the periodic table & Metals Non-metals and semi conductors
The Meaning of Stoichiometry and the Coefficients in a Reaction Equation
The Mole Concept and Finding Molar Mass
The nature of covalenting bonding & Predicting the formula of covalent bonds
The nature of solutions of ions
The Physical separation of substances
THE PHYSICCAL PROPERTIES OF MATTER
The role of Kinetic Energy in Phase Changes
TO DRAW A Lewis dot diagrams of covalent compounds
Types of Chemical Reactions - Combustion (Pt.2) &Summary
Types of Chemical Reactions - First 4 Types
Unbranched Alkanes and their Geometry
When to use each separation method
Writing electron configurations of atoms in full and core notation
Writing electron configurations of ions, and the copper and chromium exceptions
Percent Yield and Purity
Percent Yield and Percent Purity:
Today we study percentage yield and percentage purity. I wish you have a good journey here.
The yield is the amount of product you obtain from a reaction.
(The substances are products from the reactiom, so it is the percentage yield.)
The formula of
Percent yield calculations have three kinds:
To calculate the percent yield, use the reactant mass and product mass fill in the formula of percent yield.
To calculate the mass of product, use the mass of reactant and the percent yield fill in the formula.
To calculate mass of reactant, use the mass of product and the percent yield fill in the formula.
The medical drug aspirin is made from salicylic acid. 1 mole of salicylic acid gives 1 mole of aspirin. Given that the chemical formular
for salicylic acid is C
and the chemical formula for aspirin is C
In an experiment, 100.0 grams of salicylic acid gave 121.2 grams of aspirin. What was the percent yield?
Calculate the Mr (relative molecular mass) of the substances.
Ar: C = 12, H = 1, O = 16
So, Mr: salicylic acid = 138, aspirin = 180.
Change the grams to moles for salicylic acid
138g of salicylic acid = 1 mole
So, 100g = 100 ÷ 138 mole = 0.725 moles
Work out the calculated mass of the aspirin.
1 mole of salicylic acid gives 1 mole of aspirin
So, 0.725 moles gives 0.725 moles of aspirin
0.725 moles of aspirin = 0.725 × 180g = 130.5g
So, the calculated mass of the reaction is 130.5g
Calculate the percent yield.
The actual mass obtained is 121.2g
So, the percent yield = 121.2 ÷ 130.5 × 100% = 92.9%
The percent of a specified compound or element in an impure substances.
（these two products are the same, but they have different percent purity, so their color look different)
The formula of
calculations also have three kinds:
To calculate the percent purity, use the reactant mass and product mass fill in the formula of percentage yield.
To calculate the mass of product formed, use the mass of reactant and the percent yield fill in the formula.
To calculate the mass of reactant used, use the mass of product and the percent yield fill in the formula.
Chalk is almost pure calcium carbonate. We can work out its purity by measuring how much carbon dioxide is given off. 10 g of chalk was reacted with an excess of dilute hydrochloric acid. 2.128 liters of carbon dioxide gas was collected at standard temperature and pressure (STP).
The equation for the reaction is
(s) + 2HCl (aq) → CaCl
(aq) + H
O (l) + CO
Calculate the Mr of calcium carbonate
Ar: Ca = 40, C = 12, O = 16)
Mr of CaCO
Calculate the grams from the volume
1 mole of CaCO
gives 1 mole of CO
1 mole of gas has a volume of 22.4 liters at STP.
22.4 liters of gas of gas is produced by 100 g of calcium carbonate
And 2.128 liters is produced by 2.128 ÷ 22.4 × 100 = 9.5g
Calculate the percent purity
There is 9.5g of calcium carbonate in the 10g of chalk.
Percent purity = 9.5 ÷ 10 × 100% = 95%
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