EE CorrelationEngineering Sciences and Allied SubjectsCHEMISTRY

Defined as the science that deals with the study of the structure and properties of matter and the principles governing the changes it undergoes

CHEMISTRYBranches:Organic study of carbon compoundsInorganic study of all the properties and characteristics of other elementsAnalytical analysis and identification of substancesPhysical concerned with the natural laws and principles governing both physical and chemical changesBiochemistry concerned with materials found in living microorganisms

Elements in the study of ChemistryMatter anything that occupies space and has massMass the amount of matter present in a substanceWeight is the force needed to pull matter towards the center of the earthProperties of Matter Defined as characteristics that differentiate a substance from all other substances

Properties of MatterIntrinsic are properties that are independent of the size and shape of a substance. Example: temperature, pressureExtrinsic are properties that are related to size and shape. Example: volume, massPhysical properties that matter can show without being destroyedChemical are properties which matter can show by losing its identityExothermic Changes are physical or chemical changes that causes the release of energy from the substance to its surroundingsEndothermic Changes are physical or chemical changes where energy is absorbed by a substance

Classification of MatterPure Substance a form of matter that cannot be separated into two or more forms except by means of a chemical change. It is also characterized as having definite composition and a definite boiling point.

a. Elements are pure substances that cannot be decomposed further into simpler substances by means of chemical change

b. Compounds a pure substance with characterized by constant composition that can be broken down into elements by means of a chemical process

Classification of MatterMixture a form of matter that can be separated into pure substances by means of physical change. These substances have no definite composition nor boiling point.

a. Homogeneous mixtures whose composition are uniform and are not readily distinguishable. Solutions are considered as homogeneous mixtures.

b. Heterogeneous mixtures whose parts are readily visible and easily identifiable. Colloids are considered as heterogeneous mixtures.

Classification of MatterMATTERPure SubstanceMixtureElementCompoundMetalsNon-MetalsHomogeneousHeterogeneous

Laws governing chemical changesLaw of Conservation of Mass Matter can neither be created nor destroyedLaw of Conservation of Energy Matter can neither be created nor destroyed but can be transformed from one form to another. Proposed by Antoine Lavoisier.Law of Definite Composition Atoms combine in specific ratios when they form compounds. A pure compound is always made up of the same constituent elements combined in definite proportion by weightLaw of Multiple Proportion When two elements react to form one compound, the different weights of one that combine with the fixed weight of the other are in the ration of small whole numbers

Atomic Theory Atomic StructureAtom the smallest particle of matter; derived from the greek word atomos, which means uncut or indivisible

Molecule the smallest particle in a compound

Anode positively-charged electrode

Cathode negatively-charged electrode

Sub-atomic particlesAtomic NumberEqual to the number of protons in the nucleus of an atom

Mass Number / Atomic Weight Equal to the sum of the number of protons and the number of neutrons in an atom

ParticleMassChargeElectron9.11 x 10-28 g(-) 1.6 x 10-19 CProton1.67 x 10-24 g1.6 x 10-19 CNeutron1.67 x 10-24 g

Formula WeightUsed for compounds made up of ions and that primarily have ionic bonds

Molecular WeightUsed for compounds made up of molecules and that primarily have covalent bonds

Example: Formula weight of H20:H = 2 x 1 = 2O = 1 x 16 = 16

Formula Weight = 18 amu

MoleA counting number unit that consists of 6.022 x 1023 particles (atoms, molecules or ions). This number is called Avogadros number

Example: Calculate the number of molecules in 24.5 g of CO2.

MOLE = (mass) / (molecular weight)

Example: Calculate the volume in cubic cm occupied by 3.5 x 1026 atoms of aluminum if the density of Al is 2.70 g/cm3.

Percent by mass

Methods of expressing solution concentrationPercent by volume

Weight volume fraction (W/V)

Mole fraction (nf)

%M = (mass of substance) / (mass of solution)

%V = (volume of substance) / (volume of solution)

W/V = (weight of solute, g) / (volume of solution, ml)

nf = (moles of solute) / (moles of solution)

Molarity (M)

Methods of expressing solution concentrationMolality (m)

Normality (N)

Where:

M = (moles of solute) / (volume of solution)

m = (moles of solute) / (kilograms of solution)

N = (equivalent of solute) / (liters of solution)

equivalent of solute = (weight nfe) / (molecular weight)

nfe = number of free electrons

STEPS:

Count the number of atoms of each element on the reactant side and product sideFind out which atoms are unbalancedBalance one element at a time by assigning coefficients to each compound or formulaVerify whether balance has been achieved

Balancing Equations

Synthesis / Direct CombinationTwo or more substances (elements or compounds) react to form one product

Types of chemical reactionsMetal + Non-metal Binary compound (oxide, sulfide, halide)Non-metal + Oxygen Non-metal oxideMetal + Oxygen Metal OxideNon-metal oxide + Water OxyacidMetal Oxide + Water Metal Hydroxide (base)Metal Oxide + Non-metal Oxide Salt

A + B AB

DecompositionA compound decomposes into two or more new substances. The products formed by this reaction may either be elements or compounds. Heat is often necessary to cause this reaction.

Types of chemical reactionsHydrates Water + Anhydrous saltChlorates Chlorides + OxygenMetal Oxides Metal + OxygenCarbonates Oxide + CO2Bicarbonates Oxide + Water + CO2

AB A + B

Replacement / Single DisplacementAn element reacts by replacing another element in a compound

Types of chemical reactionsMetathesis / Double DisplacementTwo compounds react to form two new compounds.

A + BC AC + B

AB + CD AC + BD

NeutralizationA reaction that involves an acid or non-metal oxide and a base or metal oxide, forming salt and water.

Types of chemical reactionsAcid + Base Water + SaltMetal oxide (basic anhydride) + Acid Water + SaltNon-metal oxide (acid anhydride) + Base Water + SaltBasic Oxide (metal oxide) + Acid Oxide (non-metal oxide) SaltAmmonia + Acid Ammonium Salt

Example: EE Board September 2003What is the mass in grams of 1 liter of carbon monoxide at standard temperature and pressure (STP)? The molecular weight of CO is 28 g/mole, and at STP, 1 mole of any gas occupies a volume of 22.4 liters.

Example: EE Board April 2003A 0.064 kg of octane vapor (MW = 114) is mixed with 0.91 kg of air (MW = 29) in the manifold of an engine. The total pressure in the manifold is 86.1 kPa, and the temperature is 290 K. Assume octane behaves ideally. What is the partial pressure of the air in the mixture in kPa?

Example: EE Board April 2003Hydrogen peroxide solution for hair bleaching is usually prepared by mixing 5 grams of hydrogen peroxide (H2O2, MW = 34 g/mole) per 100 ml of solution. What is the molarity of the solution?

Example: EE Board April 2001The molecular diameter of CO is 3.19 x 10-8 at 300 K and pressure of 100 mmHg. What is the mean free path of the gas in cm?

Example: EE Board March 1998When 0.5 g of liquid is completely evaporated and collected in a liter manometer, the pressure is 0.25 atm and the temperature is 27C. Assuming ideal gas behavior, find the molecular weight if the gas constant is 0.0821 L-atm/mole-K.

QUIZ

What is the molecular weight of barium chloride dehydrate (BaCl2 2H2O)?How many grams of H3PO4 are confined in a 700 ml container if its normality is 0.5?What is the molality of the solution that contains 65 g of sucrose (C12H22011) dissolved in 300 g of water?How many moles of oxygen are in a 70L tank at 25C if the pressure is 2000 psi?Calculate how many moles of ammonia can be produced from 8 moles of hydrogen reacting with oxygen.