Science: Chemical Reaction Exam

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: The rate of a chemical reaction is independent of temperature.

False. it is dependent of temperature.

Chemicals that act as biological catalysts by speeding up reactions in living things are....

enzymes

One of the most effective ways to fight a small fire is to use a(n) __________----

fire extinguisher

The principle of conservation of mass is true___---

for reactions in both open and closed systems

CaCo3 represents a chemical.....

formula

The change from liquid to solid, or the reverse of melting, is called

freezing

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

Identify the reactants and the products of the reaction (see picture).

H2 O2 (reactants) H2O (products)

True or False: In a chemical reaction, chemical bonds are formed or broken.

True

True or False: Synthesis is the process of making a more complex compound from simpler substances.

True

True or False: The home fires that cause the most deaths start from carelessness with cigarettes.

True

Which two processes could be considered opposites?

a synthesis reaction and a decomposition reaction

True or False: Chemical reactions that absorb energy are said to be exothermic.

False. Endothermic

Write a balance equation for the reaction (see picture).

2 H2 + O2 >>>2H2O

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

True or False: A gas necessary for combustion to take place is carbon dioxide.

False. Oxygen.

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.

___________ changes occur when bonds form between atoms, or when bonds break and new bonds form.

Chemical

In chemical reactions, what does the principle of conservation of mass mean?

Matter is not created or destroyed

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.

What happens when chemical bonds bread and new bonds form?

a chemical reaction

What type of reaction is FeS+2 HCl-->FeCl2+ H2S?

a double replacement reaction

The ___________________ is the minimum amound of energy that must b e added to start a chemical reaction.

activation energy

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 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.....

balanced

A shorter, easier way to show chemical reactions, suing symbols instead of words is called a ----

chemical equation

The ___________ of a compund shows the ration of elements present in the compound.

chemical formula

Which brand of physical science studies the properties of matter and changes in matter?

chemistry

A rapid reaction between oxygen and a fuel is known as

combustion

The ___________ is the amount of one material present in a given volume of another material.

concentration

The opposite of vaporization is called

condensation

The principle of ________ states that during a chemical reaction, matter is not created or destroyed.

conservation of mass

The best way to put out a small kitchen fire is to

cover it or use a home fire extinguisher

A bottle of hydrogen peroxide that eventually turns into a bottle of water and oxygen gas is an example of a___________-

decomposition matter

A chemical reaction that absorbs energy in the form of heat is described as __________--

endothermic

A material used to decrease the rate of a chemical reaction is a(n)

inhibitor

Anything that has mass and takes up space is considered

matter

When a chemical reaction takes place in an open system......

matter can enter from or escape to the surroundings

The freezing point of water is the same as its

melting point

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

A burning match is an example of a(n) ________ , where matter can enter from or escape to the surroundings.

open system

Counting the number of cookies on a plate is a(n)

quantitative observation

The substances listed on the left side of a chemical equation are the______

reactants

In what way can a fire be brought under control?

remove oxygen

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.

replacement

The variable that is expected to change because of another variable is known as the

responding variable

The only sure evidence for a chemical reaction is...

the production of one or more new substances

Chemistry is.....

the study of matter and how matter changes.