Chemistry of Gases: Making Hydrogen, Oxygen, and Carbon Dioxide

Chemistry of Gases, Making Hydrogen, Making Oxygen, Making Carbon Dioxide

Free Physical Science Worksheets, Free Physical Science Lesson Plans, Free Physical Science Lab Activities

When I introduce the Chemistry of Gases I always start with these 3 mini-labs. They get my students engaged and wondering before we ever go into the meat of the lesson. Let's get started...

Lab Activity 1 - Making Hydrogen

Hydrogen is a colorless gas which is at least 15 times lighter than any other substance. It is a highly reactive and explosive gas. The sun and stars consist mainly of hydrogen gas and it has been estimated that about 90% of the universe is made up of hydrogen. Hydrogen was also used in airships in the 20th century due to its light nature, however after the Hindenburg disaster in 1937, airships quickly lost their popularity. Today hydrogen has been replaced by helium in modern airships because it is un-reactive.

In the presence of a flame hydrogen reacts so rapidly with the oxygen in the air that it explodes to produce water. This forms the basis for the hydrogen pop test and is the same reaction utilized in hydrogen fuel technology. Unlike petrol it produces zero carbon emissions and is deemed much better for the environment.

Here are the worksheets and documents you will need for this lab activity...

Part 1: Teacher Demonstration

Watch the hydrogen gas demonstration completed by your teacher and record your observations in the space provided on page 2 of this lab activity.

Part 2: Student Activity

Equipment

  • 250ml Conical flask
  • 2 x 10ml measuring cylinders
  • Delivery tube with stopper
  • Water tub/basin
  • Ring stand with clamp
  • Zinc metal pieces
  • Dilute hydrochloric acid (2M)
  • Cold water
  • Tapers/ wooden splints
  • Matches or lighter

Method

  1. Half fill the water basin with cold water.
  2. Place the measuring cylinder in the water basin and allow it to fill with water. Turn the cylinder upside down so that the mouth is resting on the bottom of the basin.
  3. Place 2-3 pieces of zinc metal into the conical flask and add 10ml of dilute HCl. Quickly seal the conical flask with the stopper.
  4. Place the delivery tube under the inverted measuring cylinder as seen in the diagram below. Secure the measuring cylinder with the clamp stand.
  5. Once the measuring cylinder is full of gas (there is no water left in it) loosen the clamp and lift it out of the water, tilting it slightly upwards. Place your finger or thumb over the mouth of the cylinder to keep the gas inside.
  6. Take a lit taper, remove your finger, and carefully place it in the mouth of the cylinder.

Diagram of Setup:

Chemistry of Gases, Making Hydrogen, Making Oxygen, Making Carbon Dioxide

Lab Activity 2 - Making Oxygen

We cannot live without oxygen – our bodies need a constant supply. Oxygen is an essential ingredient in aerobic respiration, the reaction which allows our cells to release the energy from the food that we eat. At rest, an average-sized person uses approximately 20 liters of oxygen an hour. This level increases dramatically with activity. Our atmosphere consists of approximately 20% oxygen, the rest is mainly nitrogen with a few other gases present in much lower percentages. Oxygen is very reactive and is flammable, producing both heat and light in some reactions.

Here are the worksheets and documents you will need for this lab activity...

Equipment

  • 250ml Conical flask
  • 2 x 10ml measuring cylinders
  • Delivery tube with stopper
  • Water tub/basin
  • Spatula
  • Tapers/ wooden splints
  • Matches or lighter
  • Hydrogen peroxide (7.5%) solution.
  • Manganese dioxide powder.
  • Cold water

Method

  1. Half fill the water basin with cold water.
  2. Place the measuring cylinder in the water basin and allow it to fill with water. Turn the cylinder upside down so that the mouth is resting on the bottom of the basin.
  3. Place 1 spatula-full of manganese dioxide powder into the conical flask and add 3 ml of hydrogen peroxide solution. Quickly seal the conical flask with the stopper.
  4. Place the delivery tube under the inverted measuring cylinder as seen in the diagram below. Secure using a clamp stand.
  5. Once the measuring cylinder is full of gas (there is no water left in it) loosen the clamp and lift it out of the water, tilting it slightly upwards. Place your finger or thumb over the mouth of the cylinder to keep the gas inside.
  6. Take a glowing taper, remove your finger, and carefully place it in the mouth of the cylinder.

Chemistry of Gases, Making Hydrogen, Making Oxygen, Making Carbon Dioxide

Lab Activity 3 - Making Carbon Dioxide

Carbon dioxide is another invisible gas found in our air. However, there is only a very tiny amount of it – 0.03%. Even so, carbon dioxide is important and has many uses. When yeast and sugar are mixed to make bread or pizza dough carbon dioxide is released. The holes in the bread are produced by bubbles of carbon dioxide. Likewise, when making beer and wine the yeast changes the sugar to alcohol and carbon dioxide in a process called fermentation. This reaction gives beer its foamy appearance. The bubbles in soda drinks are also carbon dioxide.

Chemistry of Gases, Making Hydrogen, Making Oxygen, Making Carbon Dioxide

When carbon dioxide gas cools to about -80oC it forms a white solid called dry ice. Unlike other substances which have a ‘wet’ liquid state, carbon dioxide skips this state and becomes a solid. Dry ice is much colder than regular ice that you can find in your freezer, so it is used in industry to keep substance very cold. It is also used to create mists or fog on stage.

Chemistry of Gases, Making Hydrogen, Making Oxygen, Making Carbon Dioxide

Green plants use up carbon dioxide from the air through photosynthesis. They then return oxygen to the air, which other living things such as humans and animals inhale, we then exhale carbon dioxide. Carbon dioxide is also released into the air when fuels are burnt in a process known as combustion.

Chemistry of Gases, Making Hydrogen, Making Oxygen, Making Carbon Dioxide

Part 1: Teacher Demo

Watch as your teacher exhales through a straw into a test tube of limewater. Record any observations and answer the questions on page 3 of this lab handout.

Part 2: Student Activity

Here are the worksheets and documents you will need for this lab activity...

Equipment

  • 2 x test tubes
  • Delivery tube with stopper
  • Plastic drinking straw
  • Marble chips (calcium carbonate)
  • Dilute hydrochloric acid (1M)
  • Limewater solution Ca (OH)2

Method

  1. Measure 5ml of limewater into the first test tube and set aside in a test tube rack.
  2. Place the marble chips into the other test tube.
  3. Add 5 ml of hydrochloric acid to the marble chips and seal with the stopper. Place the end of the delivery tube into the limewater so that the gas bubbles form in the limewater.

Diagram of Setup:

Chemistry of Gases, Making Hydrogen, Making Oxygen, Making Carbon Dioxide, lime water solution

The Chemistry of Gases Activity:

Students record their predictions and results of the lab activity. Once the activity is finished, discuss the lab activity and answer post-lab questions.

We also provided some of the Resources below for you to use in class. iTeachly Members can access all the content for the activity and the following lesson.

Students must come up with a unanimous answer for each question. Discussing the answers usually, results in some excellent dialogue on this topic.

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Chemistry of Gases, Making Hydrogen, Making Oxygen, Making Carbon Dioxide

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