The Amazing World of Chemistry

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:

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.

            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...

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.

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)

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: