01.04 Chemical Equations

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Included In This Lesson

Outline

Overview

  1. Chemical Equations – Like a recipe, a formula that shows the ingredient before the reaction and the products that result after the reaction.
    1. Reactants are to the left of the arrow and the products to the right
    2. Law of Conservation of Mass states that matter cannot be created or destroyed.
      1. Both sides of the equation should contain equal number of atoms and elements.
    3. Stoichiometry – the calculation of reactants and products in chemical reactions.
      1. Contains steps like algebra
        1. Write the balanced chemical equation.
        2. Convert the units of the given substance (A) to moles.
        3. Use the mole ratio to calculate the moles of wanted substance (B).
        4. Convert moles of the wanted substance to the desired units

Transcript

Hello and welcome to our lesson on chemical equations.

Chemical Equations are really just like a recipe, a formula that shows the ingredient before “cooking” or the reaction and the products that result after “cooking” the reaction. So in this example here the reactants, HCL (hydrochloric acid) and Na (sodium) are what you start with and the products NaCl (sodium chloride) and H2 (hydrogen) are what is created through the reaction.

The reaction could combine, separate or rearrange molecules. However, Reactants are always to the left of the arrow and the products to the right.

The Law of Conservation of Mass states that matter cannot be created or destroyed. Both sides of the equation should contain an equal number of atoms and elements. So, for example, the chemical reactants for photosynthesis are carbon dioxide and water and the products are glucose and oxygen. We can write this out with the chemical symbols and then we need to make sure the left side of the equation is balanced with the right.

Stoichiometry is the process of calculating the amounts in the reactants and/or products in a chemical reaction. There are 4 steps to completing this successfully. Contains steps like algebra

First, you must write the balanced chemical equation  (like we just did with photosynthesis. Next, you’ll convert the known units of the given substance (A) to moles then you will use the mole ratio to calculate the moles of wanted substance (B). Lastly, you’ll need to convert moles of the wanted substance to the desired units.

So now let’s work an example. Here we have a reaction that converts Gold Chloride into Gold and Chloride. What if we wanted to know the amount of Cl2 in grams that would be produced if we had 64 grams of AuCl3. The first thing to do is to convert the known grams of gold chloride into moles of gold chloride. This is done by calculating the atomic mass of AuCl3 which is 303.3g and multiplying to get the number of moles. Then you use the molar ratio of  3mol Cl2 / 2 mol AuCl3 and multiply by the moles of AuCl3. Then you convert the moles of Cl2 to grams of Cl2.

So in review, a chemical reaction is much like a cookbook recipe. The reactants are what you begin with and are on the left side of the reaction and the products are what is produced from the reaction and are on the right side of the arrow. Equilibrium is achieved on both sides of the equation as matter cannot be created or destroyed just changed. Stoichiometry is much like algebra in chemistry where we can figure out quantities such as the number of products that can be produced with a given amount of reactants. So if we wanted to know the amount of glucose a plant produced with a given amount of carbon dioxide we could quantify with stoichiometry.

Thank you for attending this review of chemical reactions. Now go out and be your best self today and happy nursing.