Compounds are pure substances that contain atoms of two or more elements chemically combined in fixed ratios. In this lab, we observed two types of compounds, Ionic compounds and Covalent compounds. Ionic compounds are chemical compounds consisting of two or more ions that are held adjacent to each other by electrical attraction. “One of the ions, called an “anion,” has a negative charge, and the other is called a “cation,” and has a positive charge. “Cations” are usually metallic atoms and “anions” are either atoms of nonmetals or polyatomic ions. “ (1) A polyatomic ion is an ion that contains at least two atoms. A covalent compound is a compound in which the atoms that are bonded share at least one pair of valance electrons, the electrons that are located in the outermost shell of an atom, as opposed to transferring electrons from one atom to another. Covalent compounds are usually formed between nonmetal atoms.
While both Ionic and Covalent Compounds contain atoms of two or more elements chemically combined in fixed ratios, their physical properties differ considerately. For instance, Ionic compounds tend to be very hard, brittle solids at room temperature. Generally, when Ionic compounds are struck with a hard object, like a hammer, they shatter. “They break or shatter because their ions are arranged in a repeating three-dimensional pattern called a “crystal lattice.” Each ion in the lattice is bonded to the surrounding ions of the opposite charge.” (2) When the compound is hit, the ions move and the lattice’s pattern changes. Ions of like charge are forced closer and repel one another, which ultimately could cause the crystal to break or shatter. In comparison to Ionic compounds, Covalent compounds are soft and spongy. Covalent compounds form distinct molecules with atoms that are bound tightly to one another. However, unlike Ionic compounds, the molecules do not interact with each other very often, except through fairly weak forces called “intermolecular forces.” This allows the molecules to move around each other very easily, because no bonds are between them. As a result, Covalent compounds are fairly flexible and spongy. Generally at room temperature, Covalent compounds tend to be liquids or gases. According to tutorvista.com, however, “a few covalent compounds, such as sugar, exist as solids at room temperature.” Ionic compounds also have very high boiling and melting points because it takes a large amount of energy for all of the positive and negative charges, which make up the crystal lattices to get ripped apart from one another.
The purpose of the Unknown White Compound Lab was to identify the unknown compound by performing several experiments. Conducting a solubility test, flame test, pH paper test, ion test, pH probe test, conductivity probe test, and synthesizing the compound will accurately identified the unknown compound. In order to narrow down the possible compounds, the solubility test was used to determine that the compound was soluble in water. Next, the flame test was used to compare the unknown compound to other known compounds such as potassium chloride, sodium chloride, and calcium carbonate. The flame test concluded that the cation in the unknown compound was potassium. Following, pH paper was used to determine the compound to be neutral and slightly
The primary goal of this laboratory project was to identify an unknown compound and determine its chemical and physical properties. First the appearance, odor, solubility, and conductivity of the compound were observed and measured so that they could be compared to those of known compounds. Then the cation present in the compound was identified using the flame test. The identity of the anion present in the compound was deduced through a series of chemical tests (Cooper, 2009).
This experiment sought to utilize melting point, boiling point, infrared (IR) spectroscopy, and the index of hydrogen deficiency (IHD) to identify the structures of two unknown compounds. To ensure the successful identification of the unknowns, the molecular formula for each compound was found first. What the molecular formula does is that it allows chemists to identify elements present in a compound as well as the quantity of each element. The issue with this is that there are various compounds that share the same molecular compound yet are different in reactivity and connectivity. To resolve this problem, other measures such as finding functional groups based on IR spectroscopy, determining the boiling or melting point of a compound, and identifying the bond/ring structures using IHD are taken.
Covalent compounds are formed when two or more non-metals react together. The covalent compound is actually made of molecules, and the name given depends on the structure of these molecules. Prefixes, like di- for two, tri- for three, tetra- for four, and so forth, are frequently used. Thus, NO2 is nitrogen dioxide and N2O4 is dinitrogen
Ionic liquids (ILs) are liquids composed entirely of ions. Molten salt is the term normally reserved for those systems that are liquid at high temperatures, for example NaCl (table salt is a liquid at ≈ 800 0C). Room-temperature ILs are liquid below 100˚C, have received considerable attention as substitutes for volatile organic solvents. Due to their remarkable properties, such as negligible vapour pressure, large liquidous range, high thermal stability, good ionic conductivity, high electrochemical stability, they are considered favourable medium candidates for chemical syntheses. ILs are usually categorized into four types based on their cation segment: 1) alkylammonium-, 2) dialkylimidazolium-, 3) phosphonium- and 4) N-alkylpyridiniumbased ILs (Figure 1). Ionic liquids are generally composed of a bulky organic cation, such 1-butyl-3 methylimidazolium and typically an inorganic anion such as a halide. Below are the chemical structures of some common cations and anions used to make ILs.
1 One difference between mixtures and compounds is that compounds have a certain composition as opposed to mixtures that can be varied. Chemical compounds are made up of at least two elements that are bonded together in a fixed mass ratio that can only be split apart by chemical means. And a mixture is a substance created by merging at least two different materials with no chemical reaction. Also compounds can only be separated if they are destroyed. But the elements in mixtures can be physically separated from each other easily. Another dissimilarity is that mixtures are usually heterogeneous whereas compounds are always homogeneous. Plus the properties of compounds are completely unlike their constituents. However, in a mixture the constituents do not lose their individual properties.
Solid A was identified to be sodium chloride, solid B was identified to be sucrose, and Solid C was identified to be corn starch. Within the Information Chart – Mystery White Solid Lab there are results that distinguishes itself from the other 4 experimental results within each test. Such as: the high conductivity and high melting point of sodium chloride, and the iodine reaction of corn starch. Solid A is an ionic compound due to its high melting point and high electrical conductivity (7), within the Information Chart – Mystery White Solid Lab there is only one ionic compound which is sodium chloride, with the test results of Solid A, it can be concluded that is a sodium chloride. Solid B was identified as sucrose due to its low electrical
Introduction The purpose of this lab was to observe physical properties determined by intermolecular attractive forces, such as boiling point, melting point, and solubility. During this lab the soulbility of solids were observed. While testing boiling and melting point, the solid changed to a liquid.. By using different solids, it took different times in order for the chemical to break down, due to different molecular structures.
Every chemical element or compound have specific properties that make them different than the other. However, these properties help us to understand every element or compound in which they can be used and how we can deal with them. These properties can be chemical properties which are defined as "that property must lead to a change in the substances ' chemical structure", such as heat of combustion and flammability ("Physical and Chemical…"). Also, these properties can be physical properties which are defined as the properties "that can be measured or observed without changing the chemical nature of the substance", such as mass, volume, boiling and freezing points ("Physical and Chemical…"). These two properties are related to each other. For
• The use of a catalyst will speed up the reaction as long as the catalysts electrode potentials are feasible for each step in the reaction. Since a catalyst lowers the activation energy and takes the reaction through a different route, according to the Maxwell-Boltzmann diagram, at a constant temperature more particles are able to react as demonstrated by the diagrams below:
Humans, bears, and trees all have one thing in common, they all have atoms and molecules. They also need the four elements of life to survive, Carbon, Hydrogen, Oxygen and Nitrogen. (CHON) An atom is the smallest part of an element that is still that element. A molecule is two or more atoms joined and acting as a unit. There are four different types of molecules, they are, carbohydrates, lipids, proteins, and nucleic acids.
its state (Solid, liquid, gas); thus water has a higher melting point and a higher boiling
The Periodic Table of Elements is commonly used today when studying elements. This table’s history begins in ancient times when Greek scientists first started discovering different elements. Over the years, many different forms of the periodic table have been made which set the basis for the modern table we use today. This table includes over 100 elements and are arranged by groups and periods. Groups being vertical columns and periods being horizontal columns. With all of the research conducted over the years and the organization of this table, it is easy to use when needed.
Solids are more stable than liquids and gases. One type of solid is a Crystalline solid. The particles in a crystalline solid have a regular repeating pattern. The types of crystalline solids are metals, alloys, salts, valence crystals, molecular crystals, polymers, and plastics.
Chemical reactions involve the making and breaking of bonds. It is essential that we know what bonds are before we can understand any chemical reaction. To understand bonds, we will first describe several of their properties. The bond strength tells us how hard it is to break a bond. Bond lengths give us valuable structural information about the positions of the atomic nuclei. Bond dipoles inform us about the electron distribution around the two bonded atoms. From bond dipoles we may derive electronegativity data useful for predicting the bond dipoles of bonds that may have never been made before.