“A WINNER knows how much he has to LEARN,

even when he is considered an EXPERT byothers.

A LOSER wants to be considered an EXPERT by others before he

has learned enough toknow how LITTLE he knows.”

CHEMISTRY

- From egyptian kēme, meaning “earth”- the science concerned with the

composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.

Hypothesis – A statement or idea that describes or attempts to explain observable information.

Experiment – Is a controlled testing of the properties of a substance or system through carefully recorded measurements.

Theory – The result of thorough testing and confirmation of a hypothesis. A theory predicts the outcome of new testing based on past experimental data.

Law – A hypothesis or theory that is tested time after time with the same resulting data and thought to be without exception

1. Who is said to be the founder of the scientific method?

A. Alexander FlemingB. Joseph PriestlyC. Galileo GalileiD. Antoine Lavoisier

2. In the universe, it is anything that occupies space and has mass.

A. MatterB. IsotopeC. AtomD. Solid

Matter - anything that occupies space and has mass (i.e., anything that has density). It commonly exists in three phases: solid, liquid, and gas.

3. Electron came from the greek word:A. HeliosB. ElektraC. AmberD. Volta

4. Which of the following falls under fluids?

A. gasB. solidC. liquid.D. both a & c.

5. The state of matter which occupies the whole space available is

A. gasB. solidC. liquidD. both a & c.

6. It is a property of matter which can be measured by changing the identity and composition of a substance.

A. ChemicalB. extensiveC. physicalD. extrinsic

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7. Which of the following is not an extensive property?

A. EnergyB. WeightC. Boiling pointD. Length

THE ATOMAtom is the basic building block of

matter. It is the smallest particle of element.

An ELEMENT is a fundamental type of matter in which all of the atoms in the material are the same.

The atomic number of an element is the number of protons that is contained in the nucleus of each of its atoms. 

Mass number or atomic weight is the sum of the number of protons and neutrons in the nucleus of the atom.

A compound is a substance with a particular ratio of atoms of particular chemical elements which determines its composition, and a particular organization which determines chemical properties.

The standard nomenclature of chemical substances is set by the International Union of Pure and Applied Chemistry (IUPAC).

8. What do you call chemically identical atoms of the same element but with different numbers of neutrons and different mass numbers.

A. IsotonesB. IsobarsC. IsotopesD. homogenous

9. Tritium hasA. 1 electron and 1 protonB. 1 proton and 1 neutronC. 1 proton and 2 neutronD. 2 proton and 1 neutron

Protium – most common hydrogen isotope

Deuterium – 1 neutron, 1 proton - non radioactive, -“heavy hydrogen”

Tritium – 2 neutrons, 1 protonradioactive

Hydrogen is the only element that has different names for its isotopes in common use today.

10. What is the most abundant element in the universe?

A. nitrogenB. hydrogenC. oxygenD. helium

11. What is the most abundant element in the Earth’s atmosphere?

A. nitrogenB. hydrogenC. oxygenD. helium

12. The net electrical charge of an atom under normal state is:

A. negativeB. positiveC. neutralD. infinite

13. A substance that cannot be decomposed into simpler substances by ordinary chemical reactions

A. CompoundB. MixtureC. ElementD. Homogenous

14. The subdivision of an element that can take part in a chemical reaction

A. ElementB. HydrogenC. ElectronD. Atom

15. The sub-atomic part consisting of neutrons and protons is known as

A. Nuclear fusionB. NucleonsC. NeuronsD. Neutron-proton spatial formation

IV. ATOMIC NUMBER AND MASS NUMBER

The atomic number of an element is the number of protons that is contained in the nucleus of each of its atoms.

Mass number or atomic weight is the sum of the number of protons and neutrons in the nucleus of the atom.

16. The no. of protons in the nucleus on an atom

A. Atomic number B. Mass numberC. Atomic massD. Atomic mass unit

17. The no. of protons and neutrons in the nucleus of an atom

A. Atomic number B. Mass numberC. Atomic massD. Atomic mass unit

18. 1 amu is approximately equal to

A. 6.23 x 10 ^ -27 kg B. 2.36 x 10 ^ -27 kg C. 3.62 x 10 ^ -27 kg D. 1.66 x 10 ^ -27 kg

19. The group of elements that do not normally combine with other elements to form compounds

A. Alkali MetalsB. ChalcogensC. Inert gases or noble gases D. Halogens

20. What do you call the electrons in the outermost orbitals?

A. Valence electrons B. super electronsC. holesD. active electrons

21. Calculate the mass of the product of reaction of 6.54 g of zinc with 3.21 g of sulfur.

A. 21 gB. 3.33 gC. 9.75 gD. 10.15 g

22. Calculate the mass of the oxygen that reacts with 1.24 g of methane (natural gas) to form 3.41 g of carbon dioxide and 2.79 g of water.

A. 7.38 gB. 1.86 gC. 0.62 gD. 4.96 g

ATOMIC MASSThe atomic mass (or atomic weight) of

an element is the average of the element’s isotopic masses.

1 1 2 2 3 3Atomic mass m p m p m p ...

mass of isotopes 1,2,3...

percent abundance of isotopes 1,2,3..n

n

Where m

p

.

23. Calculate the atomic mass of an element if 60.4% of the atoms have a mass of 68.9257 amu and the rest have a mass of 70.9249 amu.

A. 67.9 amuB. 69.7 amuC. 79.6 amuD. 97.6 amu

24. Calculate the atomic mass of an element if 60.4% of the atoms have a mass of 68.9257 amu and the rest have a mass of 70.9249 amu.

A. 79.6 amuB. 67.9 amuC. 96.7 amuD. 69.7 amu

Practice Problem:Calculate the percentage of bromine atoms

that have a mass of 78.9183 amu and the percentage that have a mass of 80.9163 amu. The atomic mass of bromine is 79.909 amu, and theses are the only two naturally occurring isotopes.A. 35.3%, 64.7% C. 50.4%, 49.6%B. 47.5% , 52.5% D. 63.2%, 36.8%

FORMULA MASSThe formula mass (or formula weight) is the sum of the

masses of all atoms in a given formula.

THE MOLE A mole is the amount of pure substance containing the same

number of chemical units, as there are atoms in exactly 12 grams of carbon-12.

AVOGADRO’S NUMBEROne mole refers to Avogadro’s number of particles of

anything:

236 02 10AN .

MOLE – MASS CONVERSIONSThe formula for calculating among mass, gram-

formula mass (also known as molar mass), and the number of moles:

Where: n = number of moles m = mass of the substance in grams

M= molar mass in grams per mole

m

nFM

MOLE – NUMBERS OF PARTICLES CONVERSION

Conversion factor: • EXAMPLE:

How many particles are in 2.00 moles of SO2?

231 6 02 10mole . particles

Ans. 1.2 x 1024 particles

25. Calculate the formula mass of (NH4)2HPO4 (one type of fertilizer).

A. 125 amuB. 132 amuC. 110 amuD. 148 amu

26. Calculate the number of moles of Al atoms in 5.75 x 1024 Al atoms.

A. 19.1 mol Al atomsB. 9.55 mol Al atomsC. 4.77 mol Al atomsD. 14.3 mol Al atoms

27. Calculate the number of moles of H2 molecules in 5.75 x 1024 H2 molecules.

A. 19.1 mol H2 molecules

B. 9.55 mol H2 molecules

C. 4.77 mol H2 molecules

D. 14.3 mol H2 molecules

28. Calculate the number of molecules in 30 g NH3.

A. 1.06 x 1024 moleculesB. 3.08 x 1024 moleculesC. 1.06 x 1023 moleculesD. 3.08 x 1023 molecues

29. In a 5.00-g sample of carbon, how many of the atoms have a mass of 12.01 amu?

A. NoneB. 2.507 x 1023 moleculesC. 2.507 x 1024 moleculesD. 1.44 x 1024 molecules

EMPIRICAL FORMULAAn empirical formula is a formula that gives the simplest whole-

number ratio of atoms in a compound.

Steps for Determining an Empirical FormulaStart with the number of grams of each element, given in the

problem. If percentages are given, assume that the total mass is 100 grams so

that the mass of each element = the percent given.2. Convert the mass of each element to moles using the molar mass

from the periodic table.3. Divide each mole value by the smallest number of moles calculated. Round to the nearest whole number. This is the mole ratio of the

elements and is represented by subscripts in the empirical formula. (If one of the numbers is 1.5, you would multiply each number by 2, and get a whole number of 3).

30. Calculate the empirical formula of “hypo,” used in photographic development, consisting of 29.1% Na, 40.5% S, and 30.4% O.

A. NaS2O2

B. NaS2O3

C. Na2S4O3

D. Na2S2O3

MOLECULAR FORMULAOnce the empirical formula is found, the molecular formula

for a compound can be determined if the molar mass of the compound is known.

Steps for Determining molecular Formula1. Find the empirical formula2. Find the mass of the empirical unit.3. Divide the molecular mass of the compound by the mass

of the empirical formula.4. Multiply all the atoms (subscripts) of the empirical formula

by this ratio to find the molecular formula.

31. Calculate the molecular formula of a compound with molar mass 104 g/mol composed of 92.3% carbon and 7.7% hydrogen.

A. C8H8

B. C7H14

C. C2H3

D. C7H8

CHEMICAL REACTIONA chemical reaction is a process in which

a substance or a combination of substances undergo a change in appearance or properties, and further transform into a different substance or a combination of new substances.

CLASSIFICATION OF CHEMICAL REACTIONS

DIRECT COMBINATION OR SYNTHESIS

A B AB

DECOMPOSITION

AB A B

SINGLE – REPLACEMENT REACTIONS

A BC AC B

Double – Replacement Reactions

AB CD AD CB

32. The reaction Na2O + H2O 2NaOH illustrates a

A. Synthesis ReactionB. Metathesis ReactionC. Single Replacement ReactionD. Decomposition Reaction

33. The reaction Ba(OH)2 + 2CuCNS Ba(CNS)2 + 2CuOH is an example of

A. Synthesis ReactionB. Metathesis ReactionC. Single Replacement ReactionD. Decomposition Reaction

34. The decomposition of a given compound can be carried out

A. by heating the compoundB. by passing the electric current while

heatingC. by passing the electric currentD. either by passing electric current or

heating

I. UNITS OF CONCENTRATION MOLE FRACTIONThe number of moles of solute divided

by the number of moles of solvent and all solutes.

A BA B

A B A B

n nX or X

n n n n

NORMALITYThe number of gram equivalent weights

of solute per liter. A solution is “ normal” if there is exactly one gram equivalent weight per liter.

nORMALITYsolution in liters

Equivalent weight in grams

V

MOLARITYMolarity (M) is defined as the number of

moles of solute dissolved in 1 liter of solution. In other words, molarity is a ratio between number of moles of solute and the number of liters of solution.

( )

solute

solution L

nM

V

FORMALITYThe number of gram formula weights

(i.e., molecular weights in grams) per liter of solution.

FORMALITYsolution in liters

Formula weight in grams

V

MOLALITYMolality (m) is defined as the number of

moles of solute dissolved in 1 kg of solvent. In other words molality is the ratio between the number of moles of solute and the mass of the solvent expressed in kilograms.

solute

solvent solvent

mass soluten MM solute

mkg kg

PERCENT OF VOLUMEPercent of volume refers to the number

of millilitres of solute dissolved in 100 ml of solution.

% 100volume solute

volume xvolume solution

DILUTIONDilution is the process of adding solvent (usually

water) to a concentrated solution to achieve a solution of the desired concentration. When we dilute a solution, we do not change the number of moles of solute present, we simply add more solvent. Thus,

Molesof soluteafterdilution=Molesof solutebeforedilution

after before

after before

n n

MV MV

35. Calculate the molarity of a 250-mL solution containing 80.0 mmol of solute.

A. 0.567 MB. 0.320 MC. 0.118 MD. 0.235 M

36. Calculate the number of moles of solute required to make 50.00 mL of 1.500 M solution

A. 0.025 molB. 0.75 molC. 0.075 molD. 0.25 mol

37. Calculate the molarity of a solution after 1.70 L of 2.06 M solution is diluted to 2.50 L.

A. 1.20 MB. 2.10 MC. 1.50 MD. 1.40 M

38. Calculate the mole fraction of a solution of 0.015 mol of NaCl in 50.0 g of water if the solution has a density of 1.02 g/mL.

A. 0.00536B. 0.0536C. 0.536D. 0.000536

39. Calculate the molality of an alcohol in aqueous solution if the mole fraction of the alcohol is 0.150.

A. 3.60 m alcoholB. 5.40 m alcoholC. 9.80 m alcoholD. 10.12 m alcohol

ACIDS AND BASES

ACIDS Acid is any compound that dissociates H+ ions into water .

Acids with 1,2, and 3 ionizable hydrogen atoms are called monoprotic, diprotic, and triprotic acids, respectively.

Properties of Acids:

1. Acid conducts electricity in aqueous solutions2. Acids have a sour taste3. Acids turn blue litmus paper to red4. Acids have pH between 0 and 75. Acids neutralizes bases6. Acids react with active metals to form hydrogen7. Acids react with oxides and hydroxides to form salts and water

pH Equation:

For a partially ionized compound, X, in a solution of known molarity, M, the ionic concentration is:

1pH log

H

X fraction ionized M

BASESBase is any compound that dissociates OH- ions into water.Bases with 1, 2, and 3 replaceable hydroxide ions are called

monohydroxic, dihydroxic, and trihydroxic bases, respectively. Properties of Basis:

1. Bases conduct electricity in aqueous solutions2. Bases have bitter taste3. Bases turn red litmus paper to blue4. Bases have pH between 7 and 145. Bases neutralize acids, forming salts and water

pOH Equation:

pH and pOH Relationship:

1pOH log

OH

14pH pOH

40. Battery acid is the common name for A. formic acidB. hydrochloric acidC. nitric acidD. sulfuric acid

41. When one element causes the oxidation of another element, it is

A. oxidizedB. an acidC. reducedD. a base

42. According to the Bronsted Theory, an acid is

A. a proton donorB. a proton acceptorC. an electron donorD. an electron acceptor

43. The pH of an acid solution is

A. 3B. 7C. 9D. 10

44. The pH of a solution with a hydrogen ion concentration of 1 x 103 is

A. +3B. -3C. ±3D. +11

45. The pH concentration of a solution that has a hydroxide ion concentration of 1 x 10-4 mol/L is

A. 4B. -4C. 10D. -10

46. A 10-6 M HCl solution is diluted to 100 times. The pH of the diluted solution would be

A. between 6 to 7B. between 7 to 8C. equal to 7D. equal to 10

47. A substance which can act both an acid and a base is:

A. allotropicB. amphotericC. isotopicD. amorphous