Edexcel IGCSE Chemistry: Oxygen & Oxides
How does carbon dioxide make carbonated drinks?
Although carbon dioxide is not very soluble in water at normal atmospheric pressure, it becomes much more soluble when put under pressure. Use of this is made in making fizzy drinks.
Describe the laboratory preparation of carbon dioxide.
Calcium carbonate in the form of marble chips reacts with hydrochloric acid to produce carbon dioxide. Carbon dioxide is not very soluble in water so it can be collected over water without much being lost. It can also be collected by downward delivery in air, as it is more dense than air.
What are the characteristics of carbon and sulfur oxides?
Carbon dioxide and sulfur dioxide are acidic oxides. They dissolve in water to form acidic solutions.
How is carbon dioxide used in fire extinguishers?
Carbon dioxide does not support combustion and is more dense than air, so it sits on top of the burning fuel and prevents oxygen from getting to it.
How does carbon dioxide contribute to the environment?
Carbon dioxide is a greenhouse gas and may contribute to climate change.
How dense is carbon dioxide?
Carbon dioxide is more dense than air.
Is carbon dioxide soluble?
Carbon dioxide is not very soluble in water.
Describe the laboratory preparation of oxygen in air.
Hydrogen peroxide, H₂O, decomposes slowly to form water and oxygen. The speed of the decomposition is increased by adding solid manganese dioxide, MnO₂, which acts as a catalyst for the reaction.
How does magnesium react with oxygen in air?
It burns with a bright, white flame to form a white powder.
How does Carbon react with oxygen in air?
It burns with a yellow-orange flame to form a colourless gas.
How does copper (II) carbonate thermally decompose?
It goes from green to black, resulting in carbon dioxide and carbon monoxide.
How does zinc carbonate thermally decompose?
It goes from white to yellow when hot and white again when cold. It gives Zinc oxide and carbon dioxide.
How does calcium carbonate thermally decompose?
It stays white as it gives calcium oxide and carbon dioxide.
How does sodium carbonate thermally decompose?
It stays white, not changing and does not decompose in a Bunsen flame.
Give two uses of carbon dioxide.
Making carbonated drinks, and in fire extinguishers.
What are the characteristics of Magnesium Oxide?
MgO is a basic oxide. It is very slightly soluble in water and a saturated solution will have a pH of about 10. It reacts with water to form a solution of magnesium hydroxide.
What are the gases present in air? What are their percentage volumes?
78% Nitrogen; 21% Oxygen; 0.9% Argon; 0.04% Carbon dioxide.
How can Iron be used in an experiment to calculate the percentage of oxygen in air?
Place wet iron filings in the end of a burette and place it upside-down in a basin of water. Over several days the water will rise up the burette and reach a constant level. This is because the iron reacts with the oxygen in the air. The initial and final readings of the water level in the burette are taken. Percentage of oxygen = volume of oxygen used / volume of air at start × 100
How does sulfur react with oxygen in air?
Sulfur burns with a blue flame to form a colourless gas.
How does magnesium carbonate thermally decompose?
There is no observable change- it stays white and gives Magnesium oxide and carbon dioxide.
How can copper be used in an experiment to calculate the percentage of oxygen in air?
Two gas syringes are connected by a silica tube packed with copper. The apparatus are set up with 100 cm³ of air in one of the gas syringes. The copper is heated at one end of the silica tube using a blue Bunsen flame. The air is passed backwards and forwards over the copper. As the volume of gas decreases, the Bunsen flame is moved along the tube so that it is always heating fresh copper. Heating is stopped when the volume of gas in the syringe stops decreasing. The final volume of air in the syringe will be approximately 79 cm³ has reacted. That is, 21% has been used up. Therefore the air was 21% Oxygen.
