How Is a Mixture Different
from a Chemical Reaction?
You should understand that...
• boiling is a phase change (liquid to gas) and not a chemical reaction, and
• a chemical reaction can occur with one, two, or more reactants.
What do you notice? What do you expect to happen when I shake the container?
Do you think what we see here is a new substance?
What data could we collect to determine whether this was a chemical reaction?
One way to decide whether substances interact to form new substances is to try to separate the substances you combined. If you cannot separate something into its original substances, then the substances interacted to form new substances through a chemical reaction. This is critical.
Often, a mixture can have different properties from the substances. For instance, 14k gold is not as soft as 24k gold (which is pure gold). Recall that 14k gold is a mixture of silver, copper, and gold. What you do know is that 14k gold is not pure gold because it has different properties.
However, different properties cannot necessarily tell you if a chemical reaction occurred. If you can separate the combination into the original substances using a process that is not a chemical reaction, then the combination was a mixture of substances and the molecules did not rearrange.
For example, after combining the oil and vinegar, the original substances, oil and vinegar, could be separated by just letting the container sit. Oil and vinegar is a mixture. In a mixture, the substances do not interact to form new substances. The same substances are still there. The atoms and molecules have not changed.
One way to decide whether substances interact to form new substances or make a mixture is to attempt to separate the substances. In this investigation, we boiled and condensed a combination of powdered drink mix and water. we determined that the liquid substances before and after combining and separating were the same because they had the same properties. Since the substances before and after combining and separating were the same, a chemical reaction did not occur. The combination of powdered drink mix and water was a mixture of substances that you were able to separate back into the original substances.
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