Chemical Reactions

Applying Chemical Reactions

The scientists who study chemical reactions are known as chemists. Chemists observe, describe, and apply the chemical reactions that occur in nature and those that are made by humans.

Chemists play many roles in examining how the world works. Chemists often study chemical reactions in the natural world. These reactions might occur on the surface of Earth or deep beneath Earth’s crust. Chemical reactions can even occur in the atmosphere, such as when sulfur dioxide, which is produced by the combustion of sulfur-containing fuel, reacts with oxygen in the atmosphere. The productglossary term (opens in a new window) of this reaction can then react with water in the atmosphere, ultimately forming acidglossary term (opens in a new window) rain.

Some acid rain is caused by sulfurous acid:

_{S+O2→SO2$S+O_2\to S{O}_2$}  (combustion of sulfur forms sulfur dioxide)

SO2+H2O→H2SO3$S{O}_2+H_{2}O\to H_{2}S{O}_3$  (sulfur dioxide dissolves in rain drops and forms sulfurous acid)

Chemists Wear Many Coats

How does this chemist study chemical reactions that occur in nature?

Chemists also study chemical reactions that are human-made, as well as natural reactions that can be altered by humans. By studying how chemical substances react with substances inside the human body, chemists can help develop medications used to treat illnesses or diseases. Chemists may even help find new ways to make chemical reactions such as combustion and decomposition faster and more efficient.

Caving for Cures: Mining Drugs from Nature

How do chemists create human-made medications from compounds that occur in nature?

STEM and Chemical Reactions

Many chemical reactions occur naturally, but others are helped along by humans.

Fossil fuels such as coal and oil are energy sources that humans depend on every day. These fuels power cars, provide homes with electricity, and, in many ways, make daily life more comfortable and efficient. The process of burning fossil fuels in order to produce the energy we need is a combustion reactionglossary term (opens in a new window). In general terms, a hydrocarbon-based fuel combined with oxygen produces carbon dioxide, water, and energy.

The burning of fossil fuels is a fairly simple process. However, the carbon dioxide released into the atmosphere during the combustion of fossil fuels is believed to cause a certain degree of air pollution. Scientists are seeking out new ways to improve this conversion of fossil fuels into usable energy. They want to make this process quicker and easier. This includes seeking out novel methods for releasing carbon and other important elements from existing fuel sources. Some scientists even use chemical reactions to extract energy from biofuels in order to provide a new fuel source to help meet the world’s energy needs.

Green Revolution: Biomass

How can chemists produce fuel from algae?

Conservation of Mass in Chemical Reactions

In this activity, you will use attachable beads to model a chemical reactionglossary term (opens in a new window) and relate the model to conservation of mass. You will also need to use math to determine the mass of products and reactants.

Safety Precautions

• Follow all lab safety guidelines.
• Follow proper disposal and cleaning procedures after the lab.
• Wear proper safety attire, including closed-toe shoes, safety goggles, lab coats or aprons, and gloves.
• Tie back long hair.
• Do not eat or drink anything in the lab.

Objective

• In this investigation, you will identify the reactants and products in a chemical reaction, explain the law of conservation of mass, and explain how chemical reactions are represented so that mass is conserved.

Materials per Group

• colored attachable beads in the following suggested colors and numbers:
  
  • orange, 4 (nitrogen, N)
  • blue, 4 (magnesium, Mg)
  • black, 12 (carbon, C)
  • green, 4 (iron, Fe)
  • white, 24 (hydrogen, H)
  • red, 36 (oxygen, O)
• blank sheet of paper, 1
• pen, pencil, or marker  
• balance

Procedure

Use the beads to model the following chemical reactions.

• Use as many units of each reactantglossary term (opens in a new window) or product as you need to obey the law of conservation of mass.
• After forming all the reactants and products for a reaction, find the mass of the reactants. Next, find the mass of the products. Record these data in a table.

A. H2$H_2$ and O2$O_2$ react to form H2O$H_{2}O$ .
B. Mg reacts with  H2O$H_{2}O$ to form MgO and H2$H_2$ .
C. Fe reacts with O2$O_2$ to form FeO.
D. Mg3N2$M{g}_3{N}_2$ forms when Mg reacts with N2$N_2$ .
E. MgO and CO2$C{O}_2$ react to form MgCO3$MgC{O}_3$ .

When you are finished, answer the following questions.