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Catalysts speed up chemical reactions by lowering the activation energy of the reaction pathway, without being used up in the process. When added to a reversible reaction, a catalyst increases the rates of both the forward and reverse reactions equally, resulting in no change to the equilibrium position but equilibrium being reached faster. Catalysts are particularly important in industrial applications as they allow reactions to proceed more quickly.
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The document discusses two experiments that can investigate factors affecting the strength of an electromagnet other than the presence of an iron core. The first experiment would examine how the number of coils influences the number of drawing pins attracted while keeping current the same. The second would look at how the size of the current affects the number of pins for a constant number of coils.6. halides
6. halidesshaunoff
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Halides are compounds formed between halogens (F, Cl, Br, I) and metals. They have many industrial, medical, and household applications. Halides can be identified by their reaction with silver nitrate solution to form precipitates of insoluble silver halides. The hydrogen halides are colorless gases with hydrogen fluoride having an unexpectedly high boiling point due to hydrogen bonding between H-F molecules. Larger halide ions are more reactive reducing agents as their outer electrons are farther from the nucleus and more easily donated.4. g7 and g1
4. g7 and g1shaunoff
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Alkali metals react vigorously with chlorine to form metal chlorides. Lithium reacts with chlorine gas to form lithium chloride according to the chemical equation 2Li (s) + Cl2 (g) 2LiCl (s). Sodium also reacts with chlorine gas in a similar reaction to form sodium chloride, represented by the equation 2Na (s) + Cl2 (g) 2NaCl (s).3. group 7
3. group 7shaunoff
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The document discusses the chemical properties of the halogens (fluorine, chlorine, bromine, iodine, astatine) by examining their reactivity trends down the group in reactions with iron wool and hydrogen. It notes that reactivity decreases down the group, with chlorine causing iron wool to burn brightly, bromine less so, and iodine only slightly. It also examines the halogens' reactions with metals like sodium and nonmetals like hydrogen to form halides, and displacement reactions between halogens and halide ions.2. group 1
2. group 1shaunoff
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The document discusses the chemical properties of alkali metals. It explains that alkali metals react vigorously with oxygen and water. The reactivity increases down the group as the atoms get larger, shielding the outer electrons from the nucleus and making them easier to lose. Equations for reactions of lithium, sodium, and potassium with oxygen, water, and other substances are provided. Flame tests for group 2 metals are also discussed.5.displacement
5.displacementshaunoff
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The document discusses the chemical properties of halogens, specifically their oxidizing abilities in displacement reactions. It states that in displacement reactions between halogens and halides, the halogen acts as an oxidizing agent by oxidizing the halide ion and being reduced to form the halide ion itself. The order of increasing oxidizing ability among the halogens is F > Cl > Br > I. An example reaction of chlorine displacing bromine is provided, and it is explained that in the reaction, chlorine is reduced while bromide is oxidized.1. group 0
1. group 0shaunoff
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The document discusses the properties and discovery of noble gases. It notes that:
- Noble gases (group 0) are very unreactive due to their full outer electron shells. This stability makes them similar across the group.
- Helium was first discovered on the sun in 1868. Argon was discovered in the 1890s after nitrogen from air was found to contain a small quantity of an inert element.
- Ramsay realized argon needed its own group and later discovered it contained traces of other noble gases - neon, krypton, and xenon. Radon was discovered in 1900.4
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The document discusses how changing the pressure affects the equilibrium of reversible gas reactions. It states that if the pressure is increased, the equilibrium will shift in the direction that decreases the number of gas molecules. If the pressure is decreased, the equilibrium will shift in the direction that increases the number of gas molecules. It also provides the example of nitrogen dioxide and dinitrogen tetroxide, explaining that if the pressure of this system is increased, more dinitrogen tetroxide will be produced.3
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Increasing the concentration of a substance in a reversible reaction shifts the equilibrium to decrease the concentration of that substance. For example, adding more water to a reaction producing bismuth oxychloride and hydrochloric acid from bismuth chloride and water would shift the equilibrium right, producing more products. Similarly, adding more chlorine gas to a reaction producing iodine trichloride from chlorine and iodine chloride would make the mixture appear more yellow by shifting the equilibrium to the right.2
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The document discusses exothermic and endothermic reactions. It states that all reactions are exothermic in one direction, releasing heat, and endothermic in the other direction, absorbing heat. It also explains that if temperature is increased, the equilibrium will shift in the endothermic direction to decrease temperature, and if temperature is decreased, the equilibrium will shift in the exothermic direction to increase temperature. It provides the example of nitrogen dioxide and dinitrogen tetroxide, where the forward reaction is exothermic and the backward reaction is endothermic. If temperature is increased in this system, more nitrogen dioxide will be produced.6
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Ammonia is produced industrially through the Haber process, which involves reacting nitrogen and hydrogen at high pressures and temperatures. However, the reaction is reversible and does not go to completion. To maximize yield while keeping costs low, manufacturers use a compromise of 450属C and 200 atmospheres, as extremely high pressures require expensive equipment and low temperatures slow the reaction rate. Key costs in ammonia production include raw materials, energy, equipment, wages. Yield is maximized by using a catalyst, removing ammonia as it forms, and recycling unreacted gases.1
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Le Chatelier's principle states that if a system in dynamic equilibrium experiences a change, the equilibrium will shift to counteract the change. Specifically, increasing temperature shifts equilibrium towards the endothermic direction, increasing concentration shifts equilibrium away from that substance, and increasing pressure shifts equilibrium away from the gas producing side.IB 3.2.2.5
IB 3.2.2.5shaunoff
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The melting points of elements in group 1 decrease down the group because the atomic radius increases, resulting in weaker metallic bonds and a weaker attraction between the nucleus and delocalized electrons. The melting points given for lithium, sodium, potassium, rubidium, and cesium show this decreasing trend.IB 3.2.2.4
IB 3.2.2.4shaunoff
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Electronegativity decreases down a group because the atomic radius increases and shielding increases due to electrons filling new principal energy levels, making the increased nuclear charge less significant. Therefore, iodine has a larger atomic radius and attracts electron density in a covalent bond less strongly than fluorine.IB3.2.2.2
IB3.2.2.2shaunoff
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The document discusses trends in ionic radii for cations and anions. It explains that for both group 1 and group 7 elements, ionic radii increase down the group as the outer energy level moves further from the nucleus. For cations, ionic radii are smaller than atomic radii because cations have fewer electrons and greater nuclear attraction. For anions, ionic radii are larger than atomic radii because anions have more electrons and weaker nuclear attraction. Tables of atomic and ionic radii are provided for alkali metals and halogens to illustrate these trends.Ad
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- 2. Catalysts and equilibrium A catalyst is a substance that speeds up the rate of reaction by providing an alternative reaction pathway of lower energy.
- 3. Catalysts and equilibrium A catalyst is a substance that speeds up the rate without energy of reaction by providing catalyst an alternative reaction pathway of lower energy. with catalyst time
- 4. Catalysts and equilibrium A catalyst is a substance that speeds up the rate without energy of reaction by providing catalyst an alternative reaction pathway of lower energy. with catalyst When added to a reversible time reaction, a catalyst increases the rate of both the forward and reverse reactions equally. This has two results:
- 5. Catalysts and equilibrium A catalyst is a substance that speeds up the rate without energy of reaction by providing catalyst an alternative reaction pathway of lower energy. with catalyst When added to a reversible time reaction, a catalyst increases the rate of both the forward and reverse reactions equally. This has two results: there is no change to the position of the equilibrium equilibrium is reached faster. The use of catalysts is particularly important in industry.