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Vocab
Observing Chemical Change
Describing Chemical Reactions
Controlling Chemical Reactions
Fire and Fire Safety
100
Compare endothermic change and exothermic reaction.
Endothermic change is a change in which energy is taken in whereas exothermic reaction is a reaction that absorbs energy in the form of heat.
100
What two properties can matter be described as? Give a definition of these two properties.
Changes in matter can be described in terms of physical changes and chemical changes. Physical changes are changes in a substance that do not change its identity. Chemical changes are changes in which one or more substances combine or break apart to form new substances.
100
What do chemical equations use to summarize a reaction?
Chemical equations use formulas and other symbols instead of words to summarize a reaction.
100
True or false? If false, make the statement true. All chemical reactions need a certain amount of activation energy to get started.
This statement is true.
100
List the three things necessary to start and maintain a fire.
Fuel, oxygen, and heat are the three things necessary to start and maintain a fire.
200
State the conservation of mass.
Conservation of mass is that principle stating that matter is not created or destroyed during a chemical reaction.
200
When do chemical changes occur?
Chemical changes occur when bonds break and new bonds form.
200
True or false? If false, make the statement true. To describe a reaction accurately, a chemical equation must show a different number of each type of atom on both sides of the equation.
False: To describe a reaction accurately, a chemical equation must show the same number of each type of atom on both sides of the equation.
200
What factors can chemists change to control rates of reactions?
Surface area, temperature, and concentration, and by using substances called catalysts and inhibitors are all factors.
200
What happens if you know how to prevent fires in your home and what to do if a fire starts?
You're are better prepared to take action!
300
Define combustion and explain how it is related to oxygen and fuel.
Combustion is a rapid reaction between oxygen and fuel that results in a fire.
300
What two main changes do chemical reactions involve that you can observe?
Chemical reactions involve two main kinds of changes that you can observe - formation of new substances and changes in energy.
300
What are the three categories chemical reactions can be classified as?
Synthesis, decomposition, and replacement are the three categories chemical reactions can be classified as.
300
Explain why chemical reactions don't all occur at the same rate and tell how to quicken/slow down a reaction.
Some, like explosions, are very fast. Others, like the rusting of metal, are much slower. Also, a particular reaction can occur at different rates depending on the conditions. If you want to make a chemical reaction happen faster, you need to get more reactant particles together more often and with more energy. To slow down a reaction, you need to do the opposite.
300
What are the most common sources of home fires?
The most common sources of home fires are small heaters, cooking, and faulty electrical wiring.
400
Explain the role of reactants and products in a chemical equation and their placement in a chemical equation.
Reactants and products appear in a chemical equation. A reactant is a substance that enters into a chemical reaction and a product is the substance formed as a result of a chemical reaction. Reactants are on the left side of the equation, then there is an arrow representing the word "yields", and the products are on the right side of the equation.
400
What kinds of changes should you look for in a chemical reaction?
First, a color may signal that a new substance has formed. Second, a solid may appear when two solutions are mixed. A solid that forms from solution during a chemical reaction is called a precipitate. Third, a gas might be produced from solids or liquids. Although you may observe a property change in matter, the change does not always indicate that a chemical reaction has taken place.
400
List the structure of a chemical equation below and give an example problem. Answers may vary for the example.
Reactant + Reactant ----> Product + Product CaCO3 ----> CaO + CO2
400
How do inhibitors work?
Most inhibitors work by preventing reactants from coming together. Usually they combine with one of the reactants either permanently or temporarily. Inhibitors include preservatives added to food products to prevent them from becoming stale or spoiling.
400
List some items in a home that are used to prevent fires.
safety ladder smoke detector emergency phone numbers water heater furnace matches out of reach baking soda fire extinguisher
500
Explain the differences between catalysts, enzymes, and inhibitors.
A catalyst is a material that increases the rate of a reaction by lowering the activation energy. An enzyme is a biological catalyst that lowers activation energy of reactions in cells. An inhibitor is also a material that decreases the rate of a reaction.
500
List one example of an endothermic reaction and an exothermic reaction.
The reactions that occur when you fry an egg are endothermic. The expansion and movement of the gases out of a plane exerts a force that moves the plane forward is an exothermic reaction.
500
Compare an open system to a closed system.
In an open system, matter can enter from or escape to the surroundings whereas in a closed system, matter is not allowed to enter or leave.
500
Define concentration and give an example.
Concentration is the amount of a substance in a given volume. For example, adding a small spoonful of sugar ti a glass of lemonade will make it sweet. But adding a large spoonful of sugar makes the lemonade sweeter. The glass with more sugar has a greater concentration of sugar molecules.
500
What is the best form of fire safety?
The best form of fire safety is prevention.