An exothermic reaction is any reaction that once done gives out energy to its surroundings. The energy given out is usually in the form of heat energy. This release of heat energy increases the temperature of the reaction mixture itself as well as the surroundings. The reason heat energy is given out is due to the fact that during exothermic reactions, chemical bonds are being formed. Exothermic reactions can be used in everyday lives such as body warmers.
ENDOTHERMIC REACTIONS
An endothermic reaction is the opposite to that of an exothermic reaction as this type takes in energy from its surroundings. This energy obtained is in the form of heat and brings a drop in temperature making everything around and the reaction mixture to become cold. The taking in of energy is due to the fact that bonds are being broken. Endothermic reactions can be used in everyday lives such as cold packs for sports injuries.
ENTHALPY OF COMBUSTION
This is a change in enthalpy when one mole of a substance is completely burned under the standard conditions. Both the products and reactants are in their standard states. Enthalpy of combustion is a type of exothermic reaction and so it will always be negative.
ENTHALPY OF NEUTRALISATION
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This type of force is dependent upon the size of the molecules and atoms in the reaction.
Hydrogen bond
This is a strong bond that affects any bond consisting of hydrogen and an electronegative atom (fluorine, nitrogen and oxygen). Water is a good example of hydrogen bond. The boiling point of water (100oC) is due to the high number of hydrogen bonds that each molecule is able to form. Hydrogen bonds cause substances to have high boiling points. Also, hydrogen bonds affect the viscosity of a substance. The more hydrogen there are in a bond the higher the viscosity will be.
Dipole
M1 (b)
Hot packs
These work by the process of exothermic reaction. They give off heat when they dissolve in water. The hot packs work by removing the seal which then causes the water and the chemicals to mix together. In most hot packs magnesium sulphate or calcium chloride are the chemicals used because they are able to dissolve in water and produce heat. Hot packs can get as high as 90oC. Hot packs aid in reducing swelling to muscles or joints and also just to provide warmth. When a hot pack is placed on the designated area, blood flow is increased to that part of the
This reaction does not cause a rise in temperature. One other source is triboluminescence which is light produced from friction. Another source is electric discharge which is light produced when an electrical current passes through air or another, like neon, that produces a glow. Another source is light-emitting diode which is light produced when an electrical current passes through a semi-conductor which controls how well is conducts electricity.
coupling- When endergonic reactions utilize the energy that was released from an exergonic reaction. 17. energy of activation-The amount of energy that is needed in order for a reaction to start. 18. entropy-
A reactant is the substance that is used up in a chemical reaction to give product, which is the substance that is made at the end of the reaction. Besides, the energy of the molecules that determines how fast molecules are moving is known as temperature. Therefore, the rate of the reaction that happens between molecules is affected by the size of the reactant.
Endothermic reactions absorb energy while exothermic reactions release it. 2.3 How is matter classified? pure substance - matter composed of only one kind of atom or molecule mixture - a collection or two of more pure substances physically mixed together homogeneous mixture - a mixture containing substances that are uniformly distributed heterogeneous mixture - a mixture containing substances that are not evenly distributed phase - any part of a system that has uniform composition and properties elements - the 109 simplest substances from which more complex materials are
Kinetic theory states that molecules are always in constant motion. Kinetic energy and molecule velocity increases as temperature increases. Reactions require collisions between reactant molecules or atoms. In chemical reactions, the reactants change into products when molecule collide with enough energy to break old bonds to make new ones. Collisions increase or become more violent between molecules at higher temperatures or decrease as the temperature is lowered.
A redox reaction is chemical reaction that transfers electrons. If a reactants oxidation state is more positive than the product then it is undergoing
Here are several examples of chemical properties4: Heat of combustion is the energy released when a compound undergoes complete combustion (burning) with oxygen. The symbol for the heat of combustion is ΔHc. Chemical stability refers to whether a compound will react with water or air (chemically stable substances will not react). Hydrolysis and oxidation are two such reactions and are both chemical changes. Flammability refers to whether a compound will burn when exposed to flame.
The constant variable is the amount of sodium hydroxide. Literature review A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are shared pairs and bonding pairs, and the stable balance of attraction and a repulsive force between atoms, when they share electrons is called covalent bonding.
The Problem: How does temperature affect the dissolving time of an antacid tablet? Antacid tablets are medicines that help neutralize the acid in your stomach. Antacid tablets are made of numerous numbers of components, such as sodium bicarbonate (baking powder), magnesium hydroxide, critic acid, and many others. When Antacid tablets are placed in water, they undergo a chemical reaction, where the sodium bicarbonate breaks apart to make sodium and bicarbonate ions. When the bicarbonate ions collide with hydrogen ions, it produces carbonic acid.
The purpose of this lab was to see the hydrogen bonding properties by doing multiple experiments that had exemplified such things. In the drops of water on a penny, I had gotten two pipettes and counted how many drops of that liquid, either being soap water or regular water, could fit into a penny. The second lab called “Water down a string” there was two beakers and string, which was dampened with water. Holding the string at a 45 degree angle, I had to pour water from one beaker at the top of the string and have the water be transported by the string to the other. The third lab was “How curved is your meniscus” where we had to compare the curve of water, meniscus, in a glass graduated cylinder to a plastic cylinder.
Reactions in the human body produce hydrogen peroxide as a product (1). Since hydrogen peroxide is poisonous to the human body, catalase catalyzes hydrogen peroxide into water and oxygen (2 H2O2 → 2 H2O + O2) (1). According to the collision theory, a reaction can only occur if particles collide with sufficient energy to overcome the activation energy and with correct geometrical orientation (3). Increasing temperature increases the kinetic energy of the particles which means that an increase in temperature will increase the speed of the hydrogen peroxide and the catalase molecules which
This specific sort of chemical reaction is known as chemiluminescence, which is basically the emitted light caused by a chemical reaction, which doesn’t result in significant heat. The amount of catalyst needed to actually conduct the reaction is minimal, in
Properties of Ionic and Covalent Substances Lab Report Introduction The purpose of this lab was to determine which of the following substances: wax, sugar, and salt, are an ionic compound and which are a covalent compound. In order to accurately digest the experiments results, research of definitions of each relating led to the following information: ionic compounds are positive and negatively charged ions that experience attraction to each other and pull together in a cluster of ionic bonds; they are the strongest compound, are separated in high temperatures, and can be separated by polar water molecules. A covalent compound forms when two or more nonmetal atoms share valence electrons; covalent compounds are also
It is a subcategory of the standard enthalpy of reaction and defined as the energy released with the formation of 1 mole of water (Enthalpy of neutralization, 2018). Standard enthalpy of reaction is the enthalpy change that occurs in a system when matter is transformed by a chemical reaction. All products and reactants must be in their standard state (Standard enthalpy of reaction, 2017). The standard enthalpy change can be found by dividing the heat released during the reaction by the number of moles involved in the reaction (Enthalpy of neutralization,
There are many kind of calorimeter that can use to measure different things for different purposes, one of them known as a coffee cup calorimeter. Coffee cup calorimeters are often used to measure changes in solution. Since the reaction is done in the calorimeter, the change in enthalpy is measured directly by the device. • Types of Calorimeter There are two types of calorimeter, the Bomb Calorimeter and the Coffee Cup Calorimeter.