The Amazing World of Chemistry

We are the Group 5 coming from III - Pablo. Join us as we explore the exciting road towards learning Chemistry.

[pablochem5]

Concentration in Terms of Moles

Molarity

Molarity is defined to be the number of moles of a solute divided by the liters of a solution. It has a unit of mol/L or M.

Molarity =         mol of solute

                                    L of solution

  The formula for molarity is this:

Molarity =               g of solute

                      (Formula mass)(L of solution)

  Molarity has another formula in which you will first solve for the formula mass of the given substance and you will divide it with the g of solute along with the L of solution. It can be computed as:

The formula for molarity can also be derived and can be computed as follows:

Molality

Molality is a unit of concentration, defined to be equal to the number of moles of solute divided by the number of kilograms of solvent.

Molality =            Moles of solute

                                Kg of Solvent

  The formula for molality is this:

Molality =               g of solute

                       (Formula mass)(Kg of solvent)

  Molality has another formula in which you will first solve for the formula mass of the given substance and you will divide it with the g of solute along with the kg of solvent. It can be computed as:

The formula for molality can also be derived and can be computed as follows:

[pablochem5]

Concentration by Percent

Percent Concentration

-          Amount of solute dissolved in solvent. It can be computed in two ways; percent by mass and percent by volume.

Percent by Mass

-          One way in representing the concentration of a solution in terms of grams. It can be computed as;

Percent by Volume

-          It is another one way in representing the concentration if the solution asking is in volume. It can be computed as;

If the mL or L of solute, solvent or solution is asking, just derive the equation from the formula above.

  In finding the grams or L of solute or solvent, you can also use the factors of it by;

                Like an 8% KCl solution, you can make its factors by;

-          The factors can be used in percent by mass and percent by volume.

    Remember: In solving the percentage concentration, the units you’re going to use must be similar or else the answer is incorrect.

[pablochem5]

Solubility

Solubility is the property of a substance (either it’s a solid liquid or gaseous chemical substance) to dissolve and form a homogeneous mixture. This substance dissolved in another substance is called as the solute. And the substance that dissolves a solute to result in a solution is called a solvent.

            Solutions are referred to as the life supporting mixtures. And we can determine how soluble a solution is or what kind of solutions they were based on each solution’s molarity. A solution in 0.1 mol/L is slightly soluble or an unsaturated solution. A solution with more than 0.1 mol/L is soluble and classified as a saturated solution. While a solution with less than 0.001 mol/L is considered as insoluble and a supersaturated solution.

            Aside from the molarity of the solutions, we also have rules in determining the solubilities of our substances...

[pablochem5]

Double Replacement Reaction

Double displacement

This reaction takes place when a soluble and insoluble compound reacts w/ each other to yield another substance.

Water (H2O), a gas like CO2 and an insoluble compound form in the product side are the evidence of this reaction.

These reactions are in the general form of :

Example of a double displacement reaction is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate:

PbI2(S) is the evidence of this reaction, where lead (II) iodide is insoluble compound.

        Solubility - the maximum ability of substance to dissolve in solvents like water.

        Example:  Nitrates and acetates are generally soluble. Exceptions are silver acetate, mercurous acetate, and lead acetate are moderately soluble.

[pablochem5]

Single Replacement Reaction

Single Replacement

-a less reactive metal in a solution has been replaced by a more active metal.

Example: Zn(S) + 2HCl(aq)  ----à ZnCl2 ­+ H2(g)

[pablochem5]

Decomposition Reaction

Understanding the different types of chemical reactions is the key to predict the products of a certain chemical reaction from a given set of reactants. Most reactions fall under four categories; these are combination or synthesis, decomposition, single displacement or single replacement, and double displacement or double replacement. There is also a special type of reaction which is called combustion. But for now, we are going to explore the decomposition chemical reaction.

To represent heat application in a certain reaction, there is a delta symbol (Δ) below or above the arrow.

There are different types of Decomposition Reaction

Easy isn’t it? Hope you learned from this article. It takes time to memorize those templates. But don’t worry; you’ll get better to it just practice and practice. J

See you next time!

Article by: Liliane M. Suarez

                      III-Pablo

  References: INSTITUTE OF CHEMISTRY,

        College of Arts and Sciences, UPLB

        Chemistry 15.1 Instruction Manual

          Chemistry Revised edition

        Central Luzon State University

Science City of Munoz, N.E.

          Chemistry Notebook

        Mr. Jeffrey Sta. Ines (Chemistry teacher)

        Juan R. Liwag Memorial High School

[pablochem5]

Synthesis Reaction

            In chemistry, chemical synthesis is a purposeful execution of chemical reactions to obtain a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions. And in modern laboratory usage, this tends to imply that the process is reproducible, reliable, and established to work in multiple laboratories.

            Another term for this reaction is combination reaction. Synthesis reaction is the total opposite of decomposition reaction, why did I say so? Because in synthesis, two or more stable compound is being combined to form one molecule of other compound. While in decomposition, one bulk compound is decomposed into two or more stable compound.

            Aside from the difference of synthesis and decomposition, here is another difference of dehydration synthesis reaction from hydrolysis reaction. In a dehydration synthesis, molecules are bonded together through the loose of water molecules. In hydrolysis, a molecule is broken down by the addition of water.

            The word synthesis in the present day it’s meaning was first used by the chemist Hermann Kolbe.

[pablochem5]

Chemical Equation

The elements are written according to their specific symbol and the subscript numbers in the right side of an element/compound indicate how many atoms are present in the given element/compound.

There are many symbols in a chemical equation for example the + sign means that there is another product or another reactant depend where the + sign is located. The + sign is used always as separation between products or reactants and it is usually denote and in a paragraph form equation. For the arrow it is usually denoted as to yield or to produce.

For the physical state it is subscript after the stoichiometric numbers or the element. If a compound or element is in a gas form it is (g), when in liquid (l), when in solid (s), and if aqueous solution (aq). And we can also use other symbols if they are actually used or produce in a chemical reaction.

We need to consider the Diatomic Elements where they have a state of (g) and a subscript number of 2 every time they are individually put in a chemical equation.

Coefficient in the Elements/compounds are the numbers use to balance a chemical equation. Coefficients are used to equalize the number of atoms in the Elements/compounds.

Stoichiometric numbers is the ratio in the elements and compound used in a chemical equation. 

[pablochem5]

Balancing Chemical Equations

Chemical equation is written as an expression similar to a math equation that can be compared to a recipe that a chemists follows in order to produce desired results.

Let us study first the composition of chemical equations.

The number found before the element or compound (the red numbers) are called stoichiometric coefficients or simply coefficients. The coefficients are the numbers in front of the molecules that tell how many of each molecule there are.

The small numbers (the blue numbers) are called subscripts. The subscripts are the little numbers that come after an atom, it indicates how many atoms is present in an element or compound.

All elements or compounds found at the left side of the arrow are called the reactants. The reactants are the ones that undergo chemical reaction to yield desired results.

Now, the ones that can be seen in the right side of the arrow are the products. The products are the result from the chemical reaction happened.

Now that we know about the chemical equations, let us discuss about balancing an unbalanced equation.

The most important point to remember when dealing with chemical equations is that the amount of an element on one side of the equation must equal the amount of that element on the other side of the equation. This is true for each element involved in the reaction. This rule is referred to as the law of conservation of mass.

Rules in Balancing a Chemical Equation:

You may change the coefficients but you may NOT change the subscripts. You can’t change any subscripts because that would change the chemical composition of a molecule, which would change the entire reaction and create something different altogether. However, you can change the coefficients, which only change the number of molecules being used in a reaction.

It must have the same number of atoms of the same kind on both sides of the equation.

Steps in Balancing a Chemical Equation:

1.  Write the correct formula for the reactants and products.

2.  Find the number of atoms for each element on the left side. Compare those against the number of atoms of the same element.

There is one atom of Na in the reactant and also one atom at the product. There are two atoms of Cl in the reactant and one atom at the product.

3. Balance one atom at a time.

We multiply NaCl by 2 to balance the Cl.

4. Now balance the remaining atoms.

Multiply Na by 2 to balance it.

5. Write down the balanced chemical equation.

Other examples:

[labphoto]

Chemophobia is an “irrational fear of chemicals”.

In this case in the beaker there was an amino acid derivative, in some dilute hydrochloric acid. These were used to get out the amino acid from the solution as a white participate, as seen on the picture. Nothing really toxic or harmful, it’s pH was much more neutral than the pH of anyone’s stomach. It could only cause problems if someone would drink it.

Respect the chemicals and do not fear them.

[labphoto]

Fun with fluorescent dyes part 3. In this case Eosin and Rhodamin B was used.

Since I got a lot critique because I “waste chemicals what are for research and curing cancer…”, I would like to say, that according to the labels on the bottles, the Eosin expired in 1964, and the Rhodamine B expired in 1975, so non of them could be used for any kind of research.

Have You seen my portfolio? It’s over here: http://labphoto.tumblr.com/tagged/portfolio

If You would like to buy this picture, please visit: http://society6.com/labphoto/Fun-with-fluorescent-dyes-part-3_Print#1=45 -FREE Worldwide shipping

[labphoto]

A really simple and well working purification technique is to filter the reaction products through a layer of silica. This often removes highly polar byproducts and floating particles from the solution. It works similar to flash chromatography and filtration through Celite.  

[spaceplasma]

An X-class solar flare erupted on the left side of the sun on the evening of Feb. 24, 2014. This composite image shows the sun in ultraviolet light with wavelength of both 131 and 171 Angstroms.

Additional imagery from NASA Goddard’s Scientific Visualization Studio

Credit: NASA/SDO

[txchnologist]

[globalsnapthoughts]

Printing 3D Arms for Children in Sudan

[txchnologist]

Learn more at Not Impossible Labs.

Read More

[labphoto]

As described, the pure compound (a coumarine derivative) has a strong fluorescence under UV light.

[science-junkie]

Good news for all survivalists!

 Need a water filter? Peel a tree branch

If you’ve run out of drinking water during a lakeside camping trip, there’s a simple solution: Break off a branch from the nearest pine tree, peel away the bark, and slowly pour lake water through the stick. The improvised filter should trap any bacteria, producing fresh, uncontaminated water.

In fact, an MIT team has discovered that this low-tech filtration system can produce up to four liters of drinking water a day — enough to quench the thirst of a typical person.

In a paper published this week in the journal PLoS ONE, the researchers demonstrate that a small piece of sapwood can filter out more than 99 percent of the bacteria E. coli from water. They say the size of the pores in sapwood — which contains xylem tissue evolved to transport sap up the length of a tree — also allows water through while blocking most types of bacteria.

Read more

[asapscience]