IGCSE 11.1.3
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The reaction between magnesium and hydrochloric acid is exothermic, meaning it releases heat. The heat is produced from the chemical energy stored in the reactants, which converts to thermal energy during the reaction, causing the temperature of the mixture to rise. This thermal energy is then lost to the surroundings, returning the temperature to normal.
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The document discusses energy changes that occur during chemical reactions. It explains that energy is absorbed when bonds in reactants break and released when new bonds in products form. If the energy released is greater than the energy absorbed, the reaction is exothermic and releases heat. If energy absorbed is greater, the reaction is endothermic and absorbs heat. The heat of reaction, ΔH, is calculated as the energy of products minus reactants and is negative for exothermic reactions and positive for endothermic reactions. Activation energy is also defined as the minimum energy needed to start a chemical reaction.
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Here's a basic presentation on what endergonic and exergonic reactions mean and their relevance in the field on enzyme engineering
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This document provides information on energy changes that occur during chemical reactions. It discusses exothermic and endothermic reactions, and defines important terms like heat of reaction (ΔH). Several factors that affect the rate of chemical reactions are also explained, such as temperature, concentration, and the presence of catalysts. Common applications of chemical reactions like combustion and fire control are described. The document is submitted as part of a lesson on changes, energy, and time for a chemistry class.
Thermochemistry Presentation
Topic Contains:
What is Thermo Chemistry ?
Define Origin of Heat of Reaction..
Exothermic Reaction..
Endothermic Reaction..
Graphical representation of Exothermic
and Endothermic reactions..
Different type of heat reactions..
Hess’s law..
Microwave Induced green Chemistry - used as microwave
Microwave-assisted organic synthesis has several advantages over conventional heating methods:
1) Microwave reactions can be completed much faster, in minutes or even seconds, compared to hours for conventional heating. This allows for rapid optimization and higher product yields.
2) Microwave reactions often do not require solvents or require only low volumes of solvents, making the processes more economical and environmentally friendly.
3) The selective and efficient heating of microwave irradiation allows reactions to reach higher temperatures, improving reaction rates and yields while reducing byproduct formation.
New Microsoft Word Document.docx
This document discusses the theory behind microwave heating for organic synthesis. It explains that microwaves directly couple with polar molecules and ions in a substance, causing instantaneous localized superheating. This rapid and direct heating allows reactions to reach higher temperatures faster than conventional heating, increasing reaction rates and yields. The document also discusses how microwaves transfer energy faster than molecules can relax, creating a non-equilibrium condition that enhances kinetics. While microwaves do not affect activation energies or molecular collisions, the increased temperature leads to more energetic collisions and faster reaction rates.
2 4 10
The document summarizes key concepts about chemical reactions, energy in reactions, enzymes, and enzyme action from a biology textbook chapter on chemistry of life. It defines chemical reactions as processes that transform chemicals, with reactants entering and products forming. Reactions can release or absorb energy depending on differences in bond energies between reactants and products. Enzymes are protein catalysts that lower the activation energy of reactions, speeding up rates immensely and allowing life-sustaining reactions to occur efficiently. They achieve catalysis by creating an ideal microenvironment where substrates precisely bind at active sites.
Similar to IGCSE 11.1.3 (20)
Energy Consuming & Energy Releasing Reactions.pptx
Energy Consuming & Energy Releasing Reactions.pptx
Microwave Induced green Chemistry - used as microwave
Microwave Induced green Chemistry - used as microwave
More from shaunoff
5. using electromagnets
Lifts, cars, and other large electrical machines use high currents. Relays use an electromagnet to allow a small current in one circuit to control a large current in another circuit. This allows a small current to control whether a large current flows through another circuit by closing or opening a switch.
2
The circuit for a door bell contains an electromagnet that pulls an armature towards it when the circuit is closed, causing a hammer to strike the bell and produce sound. The movement of the armature then breaks the circuit, allowing the hammer to return to its original position, and this sequence repeats to make the bell ring continuously whenever the door bell button is pressed.
1
An electromagnet on a recycling plant conveyor belt is used to pick up and move metal cans. Electromagnets attract ferromagnetic metals like iron, nickel, and cobalt. Electromagnets have the advantage over permanent magnets in that their magnetic field can be switched on and off by controlling the electric current running through the magnet coils.
5
The document presents results from an experiment investigating electromagnets. It shows that increasing the number of coils or the current in an electromagnet increases the number of drawing pins attracted. Graphs illustrate the direct relationship between the number of coils/current and the number of drawing pins attracted.
4
An experiment was designed to investigate how changing the current and number of coils affects the strength of an electromagnet. The apparatus shown could be used by altering the current running through the coils or changing the number of coils wrapped around the iron core, then measuring the effect on the magnetic force produced. Results could show that increasing either the current or number of coils strengthens the electromagnet.
3
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
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
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
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
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
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
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
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
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
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.
5
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.
6
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°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
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
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
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.
More from shaunoff (20)
IGCSE 11.1.3
- 1. Exothermic reaction: energy transfer What happens to energy in the reaction between magnesium and hydrochloric acid? 1 of 35 © Boardworks Ltd 2007
- 2. Exothermic reaction: energy transfer What happens to energy in the reaction between magnesium and hydrochloric acid? No external heat source is used so the heat released during the reaction must come from the reactants. 2 of 35 © Boardworks Ltd 2007
- 3. Exothermic reaction: energy transfer What happens to energy in the reaction between magnesium and hydrochloric acid? No external heat source is used so the heat released during the reaction must come from the reactants. During the reaction, chemical energy in the reactants is converted to thermal energy (heat). This causes the temperature of the reaction mixture to rise. 3 of 35 © Boardworks Ltd 2007
- 4. Exothermic reaction: energy transfer What happens to energy in the reaction between magnesium and hydrochloric acid? No external heat source is used so the heat released during the reaction must come from the reactants. During the reaction, chemical energy in the reactants is converted to thermal energy (heat). This causes the temperature of the reaction mixture to rise. This thermal energy is eventually lost to the surroundings and the temperature of the reaction mixture returns to normal. 4 of 35 © Boardworks Ltd 2007