Which of the following is NOT a correct inference that you can make about the burning of gasoline? a. chemical bonds are broken and others are formed b. The reaction is a physical change c. new substances are produced d. energy is realeased
b. the reaction is a physical change.
A chemical equation that shows the same number of each kind of atom on both sides of the equation is said to be.....
What happens when chemical bonds bread and new bonds form?
a chemical reaction
CaCo3 represents a chemical.....
The only sure evidence for a chemical reaction is...
the production of one or more new substances
A shorter, easier way to show chemical reactions, suing symbols instead of words is called a ----
The substances listed on the left side of a chemical equation are the______
In chemical reactions, what does the principle of conservation of mass mean?
Matter is not created or destroyed
Which of the following is a balanced chemical equation a. H2O2---H2O+O2 b. 2Fe2O3+ 3 C --4 Fe +3 CO2 c. SO2 + O2 + 2 H2O--4 H2SO4 d. 2 Mg + HCl--MbCl2 + H2
b. 2Fe2O3 + 3 C-- 4Fe + 3 Co2
Which two processes could be considered opposites?
a synthesis reaction and a decomposition reaction
A bottle of hydrogen peroxide that eventually turns into a bottle of water and oxygen gas is an example of a___________-
A chemical reaction that absorbs energy in the form of heat is described as __________--
A material used to decrease the rate of a chemical reaction is a(n)
Which of the following is an example of how to supply activation energy to begin a reaction?
heat the reaction flask on a hot plate
A rapid reaction between oxygen and a fuel is known as
In what way can a fire be brought under control?
Which is the correct chemical equation for the following statement? Sodium reacts with oxygen in a 2 to 1 ratio to produce sodium oxide.
2 Na + O2---Na2O
The best way to put out a small kitchen fire is to
cover it or use a home fire extinguisher
The principle of conservation of mass is true___---
for reactions in both open and closed systems
When a chemical reaction takes place in an open system......
matter can enter from or escape to the surroundings
In a chemical equation, numbers often appear in front of a chemical fromula. These numbers tell you the_____________
number of molecules or atoms in of each substance in the reaction
Chemicals that act as biological catalysts by speeding up reactions in living things are....
Which brand of physical science studies the properties of matter and changes in matter?
Counting the number of cookies on a plate is a(n)
The variable that is expected to change because of another variable is known as the
The change from liquid to solid, or the reverse of melting, is called
The freezing point of water is the same as its
The opposite of vaporization is called
Anything that has mass and takes up space is considered
True or False: The home fires that cause the most deaths start from carelessness with cigarettes.
True or False: In a chemical reaction, chemical bonds are formed or broken.
True or False: The materials present at the beginning of a chemical reaction are called the products.
False. They are called the reactants
True or False: Synthesis is the process of making a more complex compound from simpler substances.
True or False: Chemical reactions that absorb energy are said to be exothermic.
True or False: The rate of a chemical reaction is independent of temperature.
False. it is dependent of temperature.
True or False: A gas necessary for combustion to take place is carbon dioxide.
___________ changes occur when bonds form between atoms, or when bonds break and new bonds form.
The principle of ________ states that during a chemical reaction, matter is not created or destroyed.
conservation of mass
A reaction in which one element replaces another in a compound or in which two elements in different compounds trade places is called a(n)_______ reaction.
The ___________ is the amount of one material present in a given volume of another material.
One of the most effective ways to fight a small fire is to use a(n) __________----
A burning match is an example of a(n) ________ , where matter can enter from or escape to the surroundings.
The ___________ of a compund shows the ration of elements present in the compound.
The ___________________ is the minimum amound of energy that must b e added to start a chemical reaction.
Is the reaction that occurs in the diagram endothermic or exothermic? Explain. (see candle diagram)
Exothermic because the heat from the candle is releasing energy.
When the candle was lit, a pool of liquid was formed in the area around the wick, and then spilled over the side and resolidified. Does this observation refer to a physical change or a chemical change. Explain.
Yes, because it is being reformed.
Identify the reactants and the products of the reaction (see picture).
H2 O2 (reactants) H2O (products)
Write a balance equation for the reaction (see picture).