![]() ![]() Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. ![]() Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone. The body's circulatory system transports the oxygen to the cells, where cellular respiration takes place. In tetrapods breathing brings oxygen into the lungs where gas exchange takes place, carbon dioxide diffuses out of the blood, and oxygen diffuses into the blood. Īll plants, animals, and fungi need oxygen for cellular respiration, which extracts energy by the reaction of oxygen with molecules derived from food and produces carbon dioxide as a waste product. Oxygen makes up almost half of the Earth's crust in the form of oxides. Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula OĢ. Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the chemical element with the symbol O and atomic number 8. it will determine how much hydrogen reacts and how much remains in excess.įor example, how many moles of hydrogen gas would react if you have #0.4688# moles of oxygen? ![]() Since you don't have that many moles of oxygen, it follows that oxygen is your limiting reagent, i.e. How many moles of oxygen would have been needed to react with all the hydrogen? This means that you're dealing with a limiting reagent. Notice that you have quite a significant difference, way bigger than the required #color(red)(2):1# ratio needed, between how many moles of hydrogen gas and how many moles of oxygen you have. To determine how many moles of each you have, use their respective molar masses You know that you start with #"10.0 g"# of hydrogen gas nad #"15.0 g"# of oxygen. ![]() This means that, regardless of how many moles of oxygen gas you have, the reaction needs twice as many moles of hydrogen gas in order to proceed. Notice that you have a #color(red)(2):1# mole ratio between hydrogen gas and oxygen gas. Start by taking a look at the balanced chemical equation for this reaction ![]()
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