Friday, December 25, 2009

chemistry drill 1

1. Prove that Boyle’s Law exist by indicating that the volume (375.35 mL) at 1.85 atm pressure increases if we decrease the pressure by half.
Ans: 750.7 mL

2. What is the final temperature (in Fahrenheit) at 43.85 mL if the initial temperature at 78.35 is 2988.15 K?
Ans: -159.31 oF

3. Prove that an 8 oz coke (P = 9.85 atm) has lesser pressure than 12 oz?
Ans: Unable to prove since the P at 12 oz is 0.57 atm. It violates the Law

4. Find the moles of a perfect gas if the pressure is 1385 mmHg with a volume of 500 mL at a temperature of 175 oF.
Ans: 0.03 moles

5. Iceman produced an ice cube with a density of 0.95 g/mL and a mass of 25.35 g. If the original volume of the ice is 283.45 mL at 2.75 moles, what is the original number of moles of the ice?
Ans: 0.00364 moles

6. An inflatable balloon at 35 oC can accommodate 32 L of gas. How much temperature is needed to fill the balloon with 1,785 L of gas?
Ans: 1952.34 oC

7. An ideal gas originally has 2222 mmHg pressure, 235 mL volume, and 0.85 moles at 37 oC. If the pressure and volume are doubled, and the mole increased by 75%, what is the final temperature?
Ans: 708.91 K

8. What is the pressure (mmHg) of an 8 oz ideal gas if the number of moles present at 28 oC is 0.5 moles? (1 oz = 29.6 mL)
Ans: 39,676.00 mmHg

9. How much did the volume increases (in %) at 38 oC if the original volume at 29 oC is 32 mL?
Ans: 23.68 % (volume is 41.93 mL)

10. Construct a data for Pressure, volume temperature and number of moles for an ideal gas. Use the ideal gas equation.
Ans: Any data would do as long as the final answer for PV/nT is 0.0821


Thursday, December 3, 2009


Gas laws
The early gas laws were developed at the end of the eighteenth century, when scientists began to realize that relationships between the pressure, volume and temperature of a sample of gas could be obtained which would hold for all gases. Gases behave in a similar way over a wide variety of conditions because to a good approximation they all have molecules which are widely spaced, and nowadays the equation of state for an ideal gas is derived from kinetic theory. The earlier gas laws are now considered as special cases of the ideal gas equation, with one or more of the variables held constant.

Boyle's Law
Boyle's Law shows that, at constant temperature, the product of an ideal gas's pressure and volume is always constant. It was published in 1622. It can be determined experimentally using a pressure gauge and a variable volume container. It can also be found logically; if a container with a fixed amount of molecules inside it is reduced in volume, more molecules will hit the sides of the container per unit time causing a greater pressure.
As a mathematical equation, Boyle's law is:

Where P is the pressure (Pa) and V the volume (m3) of a gas. k1 (measured in joules) is the constant from this equation- it is not the same as the constants from the other equations below.

Charles' Law
Charle's Law, or the law of volumes, was found in 1787. It says that, for an ideal gas at constant pressure, the volume is proportional to the absolute temperature (in Kelvin). This can be found using the kinetic theory of gases or a heated container with a variable volume (such as a conical flask with a balloon).

Where T is the absolute temperature of the gas (in Kelvin) and k2 (in m3 K−1) is the constant produced.

Pressure Law (Gay-Lussac’s Law)
The pressure (or Gay-Lussac's) law was found by Joseph Louis Gay-Lussac in 1809. It states that the pressure exerted on a container's sides by an ideal gas is proportional to the absolute temperature of the gas. This follows from the kinetic theory- by increasing the temperature of the gas, the molecules' speeds increase meaning an increased amount of collisions with the container walls.
As a mathematical formula, this is:

Avogadro's Law
Avogadro's Law states that the volume occupied by an ideal gas is proportional to the amount of moles (or molecules) present in the container. This gives rise to the molar volume of a gas, which at STP is 22.4 dm3 (or liters).

Where n is equal to the number of moles of gas (the number of molecules divided by Avogadro's Number).
Ideal gas laws
The combined gas law or general gas equation is formed by the combination of the three laws, and shows the relationship between the pressure, volume and temperature for a fixed mass of gas:

With the addition of Avogadro's law, the combined gas law develops into the ideal gas law:

Where R is the gas constant with a value of 0.0821 L-atm/K-mol
An equivalent formulation of this law is:


N is the number of molecules.
These equations are exact only for an ideal gas, which neglects various intermolecular effects (see real gas). However, the ideal gas law is a good approximation for most gases under moderate pressure and temperature.

This law has the following important consequences:
1. If temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas.
2. If the temperature and volume remain constant, then the pressure of the gas changes is directly proportional to the number of molecules of gas present.
3. If the number of gas molecules and the temperature remain constant, then the pressure is inversely proportional to the volume.
4. If the temperature changes and the number of gas molecules are kept constant, then either pressure or volume (or both) will change in direct proportion to the temperature.

Monday, November 16, 2009

The Atomic Theory

Atomic Theories

The idea of an atom -- the smallest particle of matter -- has intrigued mankind since the beginning of civilization.  Throughout the centuries the "view" of the atom has changed.  New ideas, and new technologies have influenced the model of the  atom.  This view of the atom is still a Theory and therefore it is still subject to change.  The  modern model of the atom is called the Quantum Model. The chart below summarizes the various atomic models that have been developed during the course of history.

Scientist & approximate Date

Name of Model, Sketch
and main idea of theory

Importance and
Improvement on previous model

Shortcomings - Problems
or why was it changed

 c.300 BC

 Atom the indivisible particle

Atomos (in ancient Greek) means "that which cannot be further broken down into smaller pieces".

  • Talks about the atom as the smallest particle of matter.
  • Defines the atom as an indivisible particle
  • Explains certain natural occurrences such as the existence of elements
  • Does not give a scientific view of the atom only a conceptual definition
  • Does not talk about subatomic particles
    (Electrons, Protons, Neutrons)



 The solid sphere model

Atoms are seen as solid, indestructible spheres (like billiard balls)

  •  Explains a lot of chemical properties such as how atoms combine to form molecules
  • Explains chemical change better than the  Particle Theory
  • Confirms the basic Laws of Chemistry: Conservation of Mass & definite Proportions
  •  Does not include the existence of the nucleus
  • Does not explain the existence of ions or isotopes
  • Does not talk about subatomic particles
    (Electrons, Protons, Neutrons)

J.J. Thomson

 The raisin bun Model or the
chocolate chip cookie model :
 Atoms are solid spheres made-up of a solid positive mass (or core) with tiny negative particles embedded in the positive core.

  •  Infers on the existence of electrons and protons
  • Introduces the concept of the nucleus
  • Infers on the relative nuclear density and atom mass of different atoms
  •  Does not explain the existence of electrons outside the nucleus does not explain the role of electrons in bonding
  • Does not talk about neutrons therefore can't explain radioactivity and the existence of isotopes

c. 1905

 The Planetary Model

Famous Gold Leaf Experiment proves that the nucleus is positive and the electrons are outside the nucleus.


  •  Does not place electrons in definite energy levels around the nucleus
  • Doesn't include neutrons in the nucleus
  • Does Not relate the valence electrons atomic charge

(Neils Bohr)

Bohr- Rutherford
c. 1920

 Electrons in Definite energy Levels around  the nucleus

Used atomic spectra to prove that electrons are placed in definite orbitals (called shells) around the nucleus.


  •  Explains the role of valence electrons in bonding
  • Relegates the number of valence electrons to the Periods of a periodic table
  • Fully explains ionic and covalent bonding
  • Places electrons in definite energy levels
  • 2 e- in the first
  • 8 e- in the second
  • 8 e- in the third

  •  It does not explain the shapes of molecules or other abnormalities that result form unevenly shared pairs of electrons (such as the abnormal behaviour of water, the difference in Carbon-Carbon Bonds between diamond and graphite etc..)

Modern Theory

Many Scientists Contributed.  Some of the more famous  are:

  • Schroedinger
  • Einstein
  • Luis De Broglie
  • Max Planck
  • Frank Hertz
  • Maxwell
  • Fermi

Quantum Mechanical Model

or Electron Cloud Model

The analogy here is that of a "beehive" where the bees are the electrons moving around the nucleus in a "cloud" of energy levels.

Advanced Theories will explain bonding and other facts about the behaviour of atoms and their chemical and physical properties in forming new compounds.



Other important facts about the particles of an atom:

Subatomic Particle



Relative Mass*











orbits around nucleus



neutral (zero)



*Relative mass means that is the electron has a mass of 1 unit, the proton and neutron will have a mass 2000 times that of the electron.

The mass number (also known as atomic mass or atomic weight) and the atomic number from the Periodic Table are very important numbers because they tell us how many subatomic particles are contained in a given atom.

The atomic number tells us the number of electrons and the number of protons., i.e. Atomic Number = Number of electrons = Number of Protons.  The atomic mass tells the total number of particles in the nucleus, i.e. Atomic Mass = # of protons + number of neutrons.

Tuesday, November 10, 2009

Branches of Chemistry

Organic Chemistry

This specific type of chemistry is concerned with elements containing carbon. Carbon is only the fourteenth most common element on earth, yet it creates the largest number of different compounds. This type of chemistry is important to the petrochemical, pharmaceutical, and textile industries. All living organisms contain at least some amount of carbon in their body.

Inorganic Chemistry

This branch of chemistry deals with substances not containing carbon and that are not organic. Examples of such substances are minerals found in the earth's crust and non-living matter. There are many branches of inorganic chemistry. They include bioinorganic chemistry, nuclear science and energy, geochemistry, and synthetic inorganic chemistry, just to name a few.

Physical Chemistry

This type of chemistry deals with the discovery and description of the theoretical basis of the behavior of chemical substances. This means also that it provides a basis for every bit of chemistry including organic, inorganic, and analytical. This chemistry is defined as dealing with the relations between the physical properties of substances and their chemical formations along with their changes.


Biochemistry is a science that is concerned with the composition and changes in the formation of living species. This type of chemistry utilizes the concepts of organic and physical chemistry to make the world of living organisms seem much clearer. Some people also consider biochemsitry as physiological chemistry and biological chemistry. The scientists that study biochemistry are called biochemists. They study such things as the properties of biological molecules, including proteins, lipids, carbohydrates, and nucleic acids. Other topics they focus on are the chemical regulation of metabolism, the chemistry of vitamins, and biological oxidation.

Analytical Chemistry

This kind of chemistry deals mostly with the composition of substances.

Other Branches
Agrochemistry - This branch of chemistry may also be called agricultural chemistry. It deals with the application of chemistry for agricultural production, food processing, and environmental remediation as a result of agriculture.

Astrochemistry - Astrochemistry is the study of the composition and reactions of the chemical elements and molecules found in the stars and in space and of the interactions between this matter and radiation.

Electrochemistry - Electrochemistry is the branch of chemistry that involves the study of chemical reactions in a solution at the interface between an ionic conductor and an electrical conductor. Electrochemistry may be considered to be the study of electron transfer, particularly within an electrolytic solution.

Environmental Chemistry - Environmental chemistry is the chemistry associated with soil, air, and water and of human impact on natural systems.

Food Chemistry - Food chemistry is the branch of chemistry associated with the chemical processes of all aspects of food. Many aspects of food chemistry rely on biochemistry, but it incorporates other disciplines as well.

General Chemistry - General chemistry examines the structure of matter and the reaction between matter and energy. It is the basis for the other branches of chemistry.

Geochemistry - Geochemistry is the study of chemical composition and chemical processes associated with the Earth and other planets.

Green Chemistry - Green chemistry is concerned with processes and products that eliminate or reduce the use or release of hazardous substances. Remediation may be considered part of green chemistry.

Medicinal Chemistry - Medicinal chemistry is chemistry as it applies to pharmacology and medicine.

Nanochemistry - Nanochemistry is concerned with the assembly and properties of nanoscale assemblies of atoms or molecules.

Nuclear Chemistry - Nuclear chemistry is the branch of chemistry associated with nuclear reactions and isotopes.

Organic Chemistry - This branch of chemistry deals with the chemistry of carbon and living things.

Photochemistry - Photochemistry is the branch of chemistry concerned with interactions between light and matter.

Polymer Chemistry - Polymer chemistry or macromolecular chemistry is the branch of chemistry the examines the structure and properties of macromolecules and polymers and finds new ways to synthesize these molecules.

Thermochemistry - Thermochemistry may be considered a type of Physical Chemistry. Thermochemistry involves the study of thermal effects of chemical reactions and the thermal energy exchange between processes.

Sunday, June 14, 2009

Grade policies

MS Agricultural Chemistry (UPLB)

Exam = 40%
Quizzes/Assignment = 20%
Lab Report = 20%
Attendance = 10%
Lab Performance = 10%
TOTAL: = 100%

Three types of Exams will be given: Prelim, Midterm, Finals. The total items in the exam may range from 70-100.

If for an instance a student failed both Prelim and Midterm Exams, it is advisable to drop the subject unless a change in the study habit will be done or better performance in the exam. Passing grade is always 50% of the total items which has a transmuted grade equivalent to 75%. Always secure an Official dropping form from the Registrar’s Office signed by your instructor to make your dropping official. Otherwise you will be given a grade of 5.

All exams will be conducted on the last day of the exam week (Friday). A special exam will be given provided that a valid excuse slip was presented (valid excuse slips are those signed by the Physician if the reason for being absent is a sickness, or signed by a fellow LSPU Faculty if the reason is academic or school activity.) No other excuse slips will be entertained

From time to time, quizzes will be given either surprise or announced. It is expected that students should be able to do their assignment as this could be the content of the quiz the following meeting. If for an instance assignment was not collected, or quizzes were not conducted, a graded recitation will be given.

Laboratories conducted are to be written in a laboratory report. Each student is required to have its own lab notebook (brown journal) as exercises will be done by group but lab reports are submitted individually. Friday is the usual day for Laboratory exercises and the report should be submitted by Wednesday of the following week (Deadline is always 15 minutes after the call time, e.g. 3:15 or 4:15). Any late Lab reports will have an automatic deduction of 20% per meeting. If no lab report was submitted after one week (the following Wednesday), lab report is zero. However if it was still submitted after one week of delay, 5% score will be given regardless of the content of the lab report.

I. Introduction
II. Materials
III. Data and Illustration
IV. Discussion
V. Conclusion
VI. References

Students will be assessed according to how they perform the exercises. How they understand the procedure, the how they work with their partner including cooperation and coordination, cleanliness of the area and how fast they were able to finish the activity.

Attendance will be checked every meeting. A student is considered late if the instructor already started his lecture. After 15 min of the official time, the door will be closed that means no more student will be allowed to enter the room. Anyone noticed not inside the room when the lecturer checked for attendance will be marked absent. Three late will be counted as one absent. The maximum allowed absences for the entire semester is 6. If a student exceeded the maximum allowed absences, his attendance will be evaluated. If majority of the absences are excused, he is forced to drop the subject. But if in any case majority of the absences committed are unexcused, a grade of 5 will be given. However, if a student is absent for four times during a laboratory exercise (even if he is not able to consume yet his maximum absences), he is automatically dropped or given a grade of 5.

Transmuted Grade Final Grade
99.00 – 100 1.00
96.00 – 98.99 1.25
93.00 – 95.99 1.50
90.00 – 92.99 1.75
87.00 – 89.99 2.00
84.00 – 86.99 2.25
70.81 – 83.99 2.50
78.00 – 80.99 2.75
75.00 – 77.99 3.00
72.00 – 74.99 4.00
Below 72 5.00

Only Students who have taken the three exams and submitted all lab reports are qualified to take the Remedial Exam. If for any case a student misses any exam (including the special exam) or has an incomplete lab reports without any valid reasons, he is not legitimate to take the REMEDIAL EXAM and an automatic grade of 5.0 will be given. If the reason for not taking the special exam is financial problems, he is still qualified to take the remedial exam as long as her final grade ranges from 72.00-74.99 and has an average of 72.00% on his/her exams.


A = Avoid any FOUL WORDS
B = Be Responsible (it is your duty to ask your classmates what is the assignment if you are absent from the class, It’s up to you to take notes, but during lecture I will only repeat twice the items that needs to be emphasized)
C = Credits/Bonuses will be given from time to time
D = Deadline Cautious (Deadline is deadline and no extension; in case of late lab reports, you may submit it to the College Librarian)
E = Exercise Humility and Honesty (God opposes the proud but gives grace to the humble; I may not call your name if I saw you cheating, but I would directly make necessary deductions; worst score if get caught is automatically half of your score; don’t ever try to dare me because I LOVE CSI and I have my own ways of investigating cheating incidents)
F = Foods are not allowed in the Lab