Chapter 4
What are examples of physical changes that can be used as evidence that a chemical reaction has occured?
Ex: Formation of a precipitate, gas production, and/or a color change.
How do you supply activation energy at the start of a reaction?
You heat the reaction.
What is the definition of concentration?
The amount of material present in a given volume.
What is a solution?
A mixture with a solvent and at least one solute with the same properties throughout.
What can be done to a saturated solution in order to make it unsaturated?
It can be heated.
How are endothermic and exothermic reactions the same? Different?
They both involve the transfer of energy, but exothermic releases energy (when bonds form) and endothermic absorbs energy (when bonds break).
When chemical bonds break and new bonds form, what occurs?
A chemical change.
When a flame gives off black smoke, what change is occurring (physical/chemical) and why?
Chemical because:
Ex: It is burning, so it is changing into a new substance, there is a gas production, and the smoke is sign of a color change, which can indicate a chemical reaction.
What two effects do solutes have on solvents?
They can either raise the boiling point or lower the freezing point of a solvent.
A solution where more solute can still be dissolved is called a(n):
Unsaturated solution.
What does the Law of Conservation of Mass state?
That in a chemical reaction, matter is neither created nor destroyed. (All of the atoms present at the start of a reaction are present at the end).
What is a chemical equation?
A shorter way to show a chemical reaction using symbols instead of words.
What is the relationship between a chemical symbol and a chemical formula?
A chemical formula is made up of symbols and shows the ratio for elements in a compound.
Solutions and colloids are both:
Mixtures.
What types of compounds conduct an electric current in water?
Ionic compounds.
What type of reaction is FeS + HCl yields FeCl2 + H2S?
A double replacement.
What is one way to detect that a chemical reaction is occurring?
By detecting changes in properties of matter.
How do enzymes speed up chemical reactions in your body?
They provide a surface for reactions to occur on. They bring reactant molecules together, causing the reaction to require less energy and happen at body temp. Overall, they lower the necessary activation energy.
What is a solution with only a little solute called?
Dilute.
What happens to each ion when an ionic solid mixes with water?
Each ion is surrounded by water molecules.
In order for reaction to start:
There needs to be a certain amount of activation energy.
When a chemical reaction occurs in an open system, what can the matter do?
Enter from or escape to the surroundings.
What is an inhibitor?
A material used to decrease the rate of a chemical reaction.
What are three factors that affect the solubility of a substance?
Pressure, temperature, and type of solvent.
As temperature increases, the solubility of table sugar in water ____.
Increases.