Chemical Reactions

Chemical Reactions

What is a chemical reaction?

A chemical reaction is a process where a set of substances undergo a chemical change to form a different substance.

Where do chemical reactions occur?

• They happen all the time, every where in the world.

•  Every time you eat, your body uses chemical reactions to break down your food into energy.

• Other examples include metal rusting, wood burning, batteries producing electricity, and photosynthesis in plants.

What are reagents, reactants, and products?

• Reactants and reagents are the substances that are used to bring about the chemical reaction

•  A reactant is any substance that is consumed or used up during the reaction.

• The substance that is produced by a chemical reaction is called the product.

Signs of a Chemical Reaction

• heat production

• change in temperature

• formation of a precipitate

• change in color

• odor production

• light production

• formation of a gas (bubbles)

Multiple Choice

In a chemical reaction

• The atoms of the reactants always stay together to form the products
• The atoms of the reactants unbond, rearrange, and then rebond to form the products
• New atoms are formed which combine to make the products
• Some atoms disappear while others multiply to form the products

Multiple Choice

The left side of the equation below is called

• Products
• Reactants

Multiple Choice

Which observation(s) might be used as evidence that a chemical reaction occurred?

• Color change

• Odor change

• change in temperature

• All of the above

Reaction Rate

• Some happen very quickly like explosions, while others can take a long time, like metal rusting. 

• The reaction rate can be changed by adding energy, a catalyst, or changing the particle size.

• Increasing the concentration or pressure of the reactants can speed up the reaction rate.

Multiple Choice

The rate of a chemical reaction is NOT affected by which of the following:

• temperature

• concentration

• particle size (surface area)

• All of these affect reaction rates

Types of Chemical Reactions

• Synthesis

• Decomposition

• Single Replacement

• Double Replacement

• Combustion

Multiple Choice

What type of reaction is the following:
 $Zn\ +\ 2HCl\ \rightarrow\ ZnCl_2+H_2$ 

• Combination

• Decomposition

• Single Replacement

• Double Replacement

• Combustion

Multiple Choice

What type of reaction is the following:
 $BaCl_2+2KI\ \ \rightarrow\ 2KCl\ +\ BaI_2$  

• Combination

• Decomposition

• Single Replacement

• Double Replacement

• Combustion

Multiple Choice

H₂ + O --> H₂O

• Synthesis

• Decomposition

• Single replacement

• Double replacement

Multiple Choice

The following reaction is an example of what reaction type?

CoCO₃ → CoO + CO₂

• Synthesis

• Decomposition

• Single Replacement

• Double Replacement

Multiple Choice

CxHy +O₂ --> H₂O + CO₂

• Decomposition

• Double replacement

• Combustion

• Single Replacement

Poll

How do you rate your understanding of chemical reactions?

• Level 1

• Level 2

• Level 3

• Level 4