Purpose:

• identify reactants and products in chemical reactions
• identify signs of chemical reactions
• write balanced chemical equations
• classify chemical reactions

Introduction:

A chemical reaction is a chemical change, in which the reactants or starting materials change their identities to form new things called products.

Most chemical reactions display visual signs. We use these common signs to determine whether a chemical reaction has happened:

color change; fire/smoke; formation of a new solid; formation of precipitate (a clear substance turns cloudy); gas formation/fizzing

In a balanced chemical equation:

• the formulas of reactants are written on the left side of an arrow, and the products are written on the right side of the arrow.
• coefficients are used to make sure the number of atoms in reactants are equal to the number of atoms in products.

Example: In the fuel cell reaction, when hydrogen gas burns in air, it combines with oxygen gas in air to form water. Write a balanced chemical equation.

2 H2 + O2 -> 2 H2O (the number 2 in front of H2 and H2O are coefficients)

There are different methods to classify chemical reactions. You are going to practice the following types in this lab:

• combination reaction (or: synthesis reaction): two or more reactants form a single product
• decomposition reaction: a single reactant forms two or more products
• single displacement reaction (or: single replacement reaction): an element + a compound -> another element + another compound
• double displacement reaction (or: double replacement reaction): compound A + compound B -> compound C + compound D
• combustion reaction: an element or compound burns in air, oxygen gas is a reactant, heat and light are produced

Procedure:

Watch the following video, record names and formulas of reactants and products, record signs of chemical change in each reaction, write balanced equations, and identify the type of each reaction.

Chemical Reactions (Links to an external site.)

Lab Report

Chemical Reactions

1. Reaction of aluminum and iodine

Reactant(s): write name and formula of all reactants below (0.8 pt)	Product(s):write name and formula of all products below (0.8 pt)	Observations (any color change during reaction?Smoke/fire? New solid formed? Gas formed? Turned cloudy?) (0.8 pt)

Write balanced chemical equation below: (0.5 pt)

__________________________________________________________________

What type of reaction is it? ___________________________________________ (0.5 pt)

2. Reaction of hydrogen peroxide

Reactant(s): write name and formula of all reactants below (0.8 pt)	Product(s): write name and formula of all products below (0.8 pt)	Observations (any color change during reaction? Smoke/fire? New solid formed? Gas formed? Turned cloudy?) (0.8 pt)

Write balanced chemical equation below: (0.5 pt)

___________________________________________________________________

What type of reaction is it? ___________________________________________ (0.5 pt)

3. Reaction of methane in air

Reactant(s): write name and formula of all reactants below (0.8 pt)	Product(s): write name and formula of all products below (0.8 pt)	Observations (any color change during reaction? Smoke/fire? New solid formed? Gas formed? Turned cloudy?) (0.8 pt)

Write balanced chemical equation below: (0.5 pt)

__________________________________________________________________

What type of reaction is it? ___________________________________________ (0.5 pt)

4. Reaction of copper and silver nitrate

Reactant(s): write name and formula of all reactants below (0.8 pt)	Product(s): write name and formula of all products below (0.8 pt)	Observations (any color change during reaction? Smoke/fire? New solid formed? Gas formed? Turned cloudy?) (0.8 pt)

Write balanced chemical equation below: (0.5 pt)

__________________________________________________________________

What type of reaction is it? ___________________________________________ (0.5 pt)

5. Reaction of potassium iodide and lead (II) nitrate

Reactant(s): write name and formula of all reactants below (0.8 pt)	Product(s): write name and formula of all products below (0.8 pt)	Observations (any color change during reaction? Smoke/fire? New solid formed? Gas formed? Turned cloudy?) (0.8 pt)

Write balanced chemical equation below: (0.5 pt)

___________________________________________________________________

What type of reaction is it? ___________________________________________ (0.5 pt)

Post-lab Questions: answers to Q. 1 a) & 2 a) can be found online, Q. 3 can be found in lecture notes or textbook.

1. In the video it mentions the “airbag chemical reaction” in cars,

a) write a balanced chemical equation of the reaction. (0.5 pt)

b) what type of chemical reaction is it? (refer to the 5 types of chemical reactions introduced in this lab) (0.5 pt)

2. Another reaction mentioned in the video is “thermite reaction“,

a) write the balanced chemical equation for thermite reaction. (0.5 pt)

b) what type of reaction is thermite reaction? (refer to the 5 types of chemical reactions introduced in this lab) (0.5 pt)

3. Common fuels such as methane, propane and gasoline are carbohydrates. What are the two main products of combustion of all carbohydrates regardless of the identity of carbohydrate? (1 pt)