Accelerated Chemistry Blog #4

Balancing an Equation

We have discussed a lot of different topics recently in chemistry class.  The first of these, and the one we have used most frequently, is balancing chemical equations.  In order to perform this task, you need to add coefficients to the front of compounds or individual elements.  This ensures that there are an equal number of each particular element on both sides of the equation.  It was cool to learn that the amount of elements or compounds on either side of the equation can change so that it remains in balance.

The next topics we discussed were the five different types of chemical reactions.  The first of these is a synthesis, or combination reaction in which two separate reactants are combined into one product.  The second of these is decomposition.  In decomposition, one reactant is broken down into two or more products.  The third type is single replacement.  Here, an individual element replaces a similar element that is already part of a compound.  The fourth type of reaction is the double replacement.  In this type, two compounds interchange either their metal or nonmetal, creating two new compounds.  The final type of reaction is combustion.  Here, carbon dioxide and water are created through burning.  I didn't realize before this that there were this many ways to predict what the products of a chemical reaction will be.

The final topic we covered was the activity series.  Here we learned four special rules about chemical reactions and learned which metals and nonmetals were more active than others.  The first rule was that any element in the list that was given could displace any of the elements that were less active and from the same list.  The second rule stated that any of the metals above hydrogen on the list are able to displace hydrogen from the compounds HCl or H₂SO₄.  The third rule is that any metal above magnesium on the list are able to displace the hydrogen from a water molecule.  Finally, rule four states that all metals that are above silver on the list can combine with pure oxygen in a synthesis reaction.  These rules are essential in determining the products of chemical reactions.  There are a lot of hidden rules that need to be remembered.

   

We also did several activities while learning about chemical reactions and activity in class.  The first experiment we did was "Identifying Chemical Activity."  During this series of experiments, we discovered which compounds and specific elements created a chemical reaction when combined.  In addition, we found out the relative activity of these elements.  It found it really interesting that in this experiment, through combining elements and substances, we were able to discover on our own which elements are more active than others and that our results matched up with the activity series.  The other activity we did was one in which we were instructed to combine certain elements and compounds together and use experimental evidence to determine the products.  This was a great experience because even though we weren't given the products before before we started, our group was able find them by using different series of tests.  

Accelerated Chemistry Blog #3

Recently, in Accelerated Chemistry, we have been learning about many interesting and amazing topics.  The first of these topics is relative mass.  Relative mass is the idea that masses of different elements are based off of the mass of different element.  In the Periodic Table of Elements, atomic masses for the different elements are relative masses that are based on, or relative to, Carbon, or C-12. 

How Much Water Can
He Fit In His Mouth?

The next topics we discussed were the biggest and most important in the chapter.  These were the topics of Avogadro's Number, the mole, and molar mass.  Avogadro's Number, or a mole, is 6.02x10²³ of anything.  Molar mass is the mass, in grams, of 1 mole of a specific kind of atoms or molecules.  The atomic masses of the elements on the periodic table tell you the mass of 1 mole of atoms of that element in grams.  For example, for every 1 mole of mercury (Hg), there are 200.6 g of mass.  In order to better understand this concept, we performed mole problems as a class and in small groups.  Later, we performed an experiment (shown to the left) in which we had to use a mole to help us calculate how many water molecules we could fit in our mouths and how many tin cans were needed to contain 8.79x10²⁴ atoms of tin.  Through our work in groups and as a class, I now better understand the concept of moles and how to solve problems  and calculations with them.

The final topic we covered was that of percentage composition.  You can discover what percentage a single element is of the total compound by one of two ways.  The first way you can do this is by using relative mass data.  By knowing how much the total compound weighs versus how much it weighs without a specific element, you can determine what percentage of the compound was made of that element.  The second way to find percentage composition is through the formula.  By finding the total mass of the compound using the periodic table, and then finding the mass of each individual element, you can find the what percentage the element is of the total.

During this chapter I personally found the topic of a mole extremely fascinating.  By doing the mole calculations and making my mole poster, I was truly amazed to find how large a mole actually is.  Even though I do understand the concepts better , I still find it hard to comprehend that such a small mass of each element contains that many tiny atoms.  As a whole, this chapter was very eye-opening and insightful.