Chemical Reaction: Chemical Change - Video Tutorials & Practice Problems

Chemical Reaction: Chemical Change Concept 1

recall a chemical reaction an example of a chemical change and a chemical reaction itself involves chemical bonds that are broken in react ints and new chemical bonds that are formed in products. Now, we're going to say here that through the use of our senses, we can observe many of these chemical changes or chemical reactions taking place. So some observable evidence of a chemical reaction. One involves change in color. So we can have a solution that's light pink, transitioning to maybe violent or darker purple. We can have formation of gas so we can see bubbles forming or we can have precipitate. Precipitate is just a solid. We also could observe changes in temperature. So these are changes that we can see with our own eyes that are evidence that a chemical reaction has taken place.

Chemical Reaction: Chemical Change Example 1

What happens on a molecular level when a chemical reaction occurs, A bonds are broken, Bean bonds are formed, sea temperature increases or decreases, or is A. D. All of the above? Well, we talked about this earlier that there are certain changes that are observable through our senses that are evidence of a chemical reaction occurring now, bonds being broken or formed. It's harder to see that sometimes, but these are evidence that a chemical reaction has happened even on a molecular level. And we also said that changes in temperature were an observable change that illustrated chemical reaction has occurred. So a B and C are all evidence of a chemical reaction occurring. Therefore, the answer is D. All of the above.

Chemical Reaction: Chemical Change Concept 2

Now a chemical equation is just an expression that uses chemical formulas and symbols to represent chemical reactions. So here what we have is we have to and this is called sodium bicarbonate. Breaking down to give us sodium carbonate, water and carbon dioxide. Now let's talk about the different chemical formulas as well as symbols involved in this chemical equation. So these symbols of chemical equations. Here we have our era. We call this our reaction era. It's a way of saying that our reaction proceeds are reactions undergo a change to form products. Next we have this little triangle here, this triangle is a way of talking about heat being involved. So instead of literally writing the word heat, you can substitute in this triangle for it. The next are the different states that exist in terms of our compound within a chemical reaction. So here this s. Means that it is a solid. So when the chemical equation of above, sodium bicarbonate is a solid, and sodium carbonate is a solid. L. Means liquid, so water here is a liquid G. Here means gas, so carbon dioxide here is gas and here this one we don't have any chemical equation, but it does pop up in a lot of types of chemical equations. A. Q. Stands for Aquarius. What that means is that our compound or molecule in question is dissolved in a solvent like water. So when you see acquis for compound, that means it is in a water solution. Okay, so you've taken the compound and place it into water and therefore it's surrounded by water and therefore it is an acquis state. So just keep in mind these different types of chemical formulas and symbols that are pretty customary with any type of chemical equation that you're going to eventually start seeing.

Chemical Reaction: Chemical Change Example 2

So here it says, right, a chemical equation using correct formulas and symbols for the decomposition of solid sodium carbonate. Had high temperature to produce solid sodium oxide and carbon dioxide gas. All right. So, they're telling me that I have solid sodium carbonate, sodium carbonate, remember? Is N. A to C. 03 solid. They're saying that it's decomposing. I mean, that's breaking down and they're saying high temperature, which means heat is involved. So, you can put a triangle here is saying that we're producing sodium oxide. Remember, sodium and group one A. So, it's plus one in its charge oxide is +02 minus. Remember when the numbers and the charges are different. They don't cancel out the criss cross. So that would be in a 20 solid Plus carbon dioxide which is CO302, 2 gas Here. This would represent our chemical equation. This chemical equation is already balanced. We don't have to worry about that just um quite yet. This would be our balanced chemical equation that shows the decomposition of our solid sodium carbonate into sodium oxide and carbon dioxide gas