How to make Oxygen

 Oxygen and oxides

Making oxygen

Oxygen can be made from hydrogen peroxide, which decomposes slowly to form water and oxygen:

hydrogen peroxide → water + oxygen

2H₂O₂(aq) → 2H₂O(l) + O₂(g)

The rate of reaction can be increased using a catalyst, manganese(IV) oxide. When manganese(IV) oxide is added to hydrogen peroxide, bubbles of oxygen are given off.

To make oxygen in the laboratory, hydrogen peroxide is poured into a conical flask containing some manganese(IV) oxide. The gas produced is collected in an upside-down gas jar filled with water. As the oxygen collects in the top of the gas jar, it pushes the water out.

Instead of the gas jar and water bath, a gas syringe could be used to collect the oxygen.

Metal and non-metal oxides

Many metals and non-metals react with oxygen in the air when they are heated to produce metal oxides and non-metal oxides.

The table shows three of these reactions in detail.

Magnesium	Metal	Highly exothermic - magnesium burns with bright white flame	Magnesium oxide, MgO - solid white powder	Basic
Carbon	Non-metal	Exothermic - carbon glows orange when heated strongly	Carbon dioxide, CO2 - colourless gas with no odour	Acidic
Sulfur	Non-metal	Burns slowly with a blue flame	Sulfur dioxide, SO2 - colourless gas with choking smell	Acidic		Making carbon dioxide Carbon dioxide is produced whenever an acid reacts with a carbonate. This makes carbon dioxide easy to make in the laboratory. Calcium carbonate and hydrochloric acid are usually used because they are cheap and easy to obtain. calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l) Carbon dioxide can be collected over water, as shown in the diagram. Carbon dioxide is slightly soluble in water and denser than air, so another way to collect it is in a dry, upright gas jar. As the carbon dioxide falls out of the delivery tube and into the gas jar, it pushes the less dense air out of the top of the gas jar. Thermal decomposition Calcium carbonate breaks down when heated strongly. This reaction is called thermal decomposition. Here are the equations for the thermal decomposition of calcium carbonate: $$calciumcarbonate\stackrel{heat}{\to }calciumoxide+carbondioxide$$ $$CaC{O}_3(s)\stackrel{heat}{\to }CaO(s)+C{O}_2(g)$$ Other metal carbonates decompose in the same way, including: sodium carbonate magnesium carbonate copper carbonate For example, here are the equations for the thermal decomposition of copper carbonate: $$coppercarbonate\stackrel{heat}{\to }copperoxide+carbondioxide$$ $$CuC{O}_3(s)\stackrel{heat}{\to }CuO(s)+C{O}_2(g)$$ Heating metal nitrates and hydroxides The effect of heat on metal nitrates (NO3) and hydroxides (OH-) can help to determine their places in the reactivity series: Potassium, Sodium, Calcium, Magnesium Stable - does not decompose on heating Decompose to metal nitrite + oxygen Zinc, Iron, Copper Decompose to metal oxide + steam Decompose to metal oxide + oxygen + nitrogen dioxide Properties and uses of carbon dioxide Carbon dioxide is soluble in water. When it dissolves it forms a carbonic acid. $$H_{2}O(l)+C{O}_2(g)\rightleftharpoons H_{2}C{O}_3(aq)$$ Carbonic acid is what gives fizzy drinks their bubbles. At high pressures, more carbon dioxide dissolves in water, and because this reaction is reversible, when the pressure decreases carbon dioxide is released again. This explains why bubbles appear in a bottle of sparkling water when you unscrew the lid. Carbon dioxide is denser than air. It sinks, which means that it can smother a fire - starving the fire of oxygen and putting it out. This is why many fire extinguishers contain carbon dioxide gas. Carbon dioxide as a greenhouse gas Some gases in the Earth's atmosphere absorb infrared radiation. These gases are called greenhouse gases and they keep our planet warm. Carbon dioxide is a greenhouse gas. Even though it only makes up about 0.04 per cent of the atmosphere, carbon dioxide is a very important greenhouse gas because it absorbs infrared well. The greenhouse effect The Sun’s rays enter the Earth’s atmosphere. Energy is absorbed by the Earth’s surface and re-emitted at longer wavelengths, such as infrared radiation (heat). Some emitted heat passes through the atmosphere into space. Some heat is absorbed by carbon dioxide, a greenhouse gas. Heat is re-emitted in all directions and some becomes trapped within the Earth’s atmosphere. The Earth becomes hotter as a result. Water vapour and methane Other greenhouse gases are water vapour, and also methane. Even though methane is only present in tiny amounts, it is a very efficient absorber of infrared. Climate change The greenhouse effect is a natural process that keeps the Earth’s atmosphere warm. This has been essential to the evolution of life as we know it. However, since the Industrial Revolution, humans have been releasing greenhouse gases into the atmosphere faster than natural processes can remove them. For example, burning fossil fuels releases carbon dioxide. The extra carbon dioxide increases the greenhouse effect, which makes the planet warmer than it would be naturally. The increase in global temperature this causes is called global warming. Global warming is beginning to trigger big changes in the environment. The average temperature of the atmosphere and oceans is increasing slightly every decade, and this is already causing polar ice caps to melt and sea levels to rise.     🙏🙏🙏🙏 Thank you 🙏🙏🙏🙏