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Chemistry LibreTexts

Chem 11 Experiments

  • Page ID
    • 1: Using Excel for Graphical Analysis of Data (Experiment)
      An important technique in graphical analysis is the transformation of experimental data to produce a straight line. If there is a direct, linear relationship between two variable parameters, the data may be fitted to the equation of line with the familiar form y=mx+b through a technique known as linear regression. The objective of this exercise is to use Excel to explore a number of linear graphical relationships.
    • 2: The Densities of Solutions and Solids (Experiment)
      Density is a fundamental physical property of matter. Physical properties are those characteristics of a substance that can be determined without changing the chemical identity of the substance. Other physical properties include melting point and solubility. In general, since different substances have unique densities, determining the density of an unknown substance can help identify it.
    • 3: Paper Chromatography- Separation and Identification of Five Metal Cations (Experiment)
      Most chemists and many other scientists must routinely separate mixtures and identify their components. The ability to qualitatively identify the substances found in a sample can be critical. For example, an environmental chemist investigating samples of polluted ground water will want to know which toxic ions might be present in a sample. Chromatography is one of the first tools used in such situations.
    • 4: Inorganic Nomenclature (Experiment)
      In this exercise you will practice naming and writing chemical formulas for many inorganic compounds, both ionic and molecular. Before beginning the exercise you should carefully read all the sections of your text (or notes) on the names and formulas of ionic compounds, simple covalent compounds, and acids. The following is a brief summary of the Nomenclature rules for each of these types of compounds.
    • 5: Properties of Hydrates (Experiment)
      It is generally possible to remove the water of hydration by heating the hydrate. Le Chatelier’s principle predicts that an addition of heat to an endothermic reaction (heat is a “reactant”) will shift the reaction to the right (product side). Heating will shift the equation of dehydration below to the right since it is an endothermic reaction. The residue obtained after heating, called the anhydrous compound, will have a different structure and texture and may have a different color than the hy
    • 6: Types of Chemical Reactions (Experiment)
      Matter undergoes three kinds of change: physical, chemical, and nuclear. While the composition of a chemical substance is not altered by physical changes (such as freezing and evaporation), chemical changes, or reactions, result in the formation of new substances when bonds are formed and/or broken. Some relatively simple but common types of chemical reactions are illustrated in this experiment. Examples and descriptions of each reaction type appear in the following section.
    • 7: Gravimetric Analysis (Experiment)
      Gravimetric analysis is a quantitative method for accurately determining the amount of a substance by selective precipitation of the substance from an aqueous solution. The precipitate is separated from the remaining aqueous solution by filtration and is then weighed. Assuming that the chemical formula for the precipitate is known and that the precipitation reaction goes all the way to completion, then the mass of the substance in the original sample can be determined.
    • 8: Reaction Stoichiometry and the Formation of a Metal Ion Complex (Experiment)
      The net result of a reaction can be summarized by a chemical equation. In order to write a chemical equation, a chemist must identify the reactants and products, as well as the ratios in which these species react and are produced, i.e., the stoichiometry of the reaction. When two or more reactants are mixed together, it is possible to determine whether a reaction occurs by observing whether any property of the mixture changes.
    • 9: Evaluating the Cost-Effectiveness of Antacids (Experiment)
      In this exercise, two commercially available antacids are evaluated and compared by: determining the number of moles of hydronium ions neutralized per gram of each antacid. calculating the cost effectiveness of each antacid.
    • 10: Vitamin C Analysis (Experiment)
      You will need to bring a powdered or liquid drink, health product, fruit samples, or other commercial sample to lab for vitamin C analysis. You will need enough to make 500 mL of sample for use in 3-5 titrations. Be sure the product you select actually contains vitamin C (as listed on the label or in a text or website) and be sure to save the label or reference for comparison to your final results. Be careful to only select products where the actual vitamin C content is listed.
    • 11A: The Molecular Weight of Carbon Dioxide (Experiment)
      OBJECTIVES To determine the molecular weight (molar mass) of carbon dioxide based on measurements of the pressure, temperature, volume and mass of a sample of the gas. To compare the experimental molecular weight to the theoretical molecular weight of carbon dioxide.
    • 11B: The Dumas Method (Experiment)
      In the early 19th century, Jean-Baptiste Dumas, a distinguished French chemist, created a relatively simple method for determining the molecular mass of a volatile substance. In this experiment we will use a modified version of his technique to determine the molecular mass of an unknown volatile liquid.
    • 12: Calorimetry and Hess's Law (Experiment)
      The combustion of a metal in oxygen produces the corresponding metal oxide as the only product. Such reactions are exothermic and release heat. Since it is difficult to measure the enthalpy of combustion of a metal directly, in this lab it will be determined indirectly by applying Hess’s Law of Heat Summation. Hess’s Law states that the enthalpy change of an overall process is equal to the sum of the enthalpy changes of its individual steps.
    • 13: Measuring Manganese Concentration Using Spectrophotometry (Experiment)
      Spectroscopy is one of the most powerful analytical techniques in modern science. Before the advent of spectrophotometric techniques, a chemist interested in determining the amount of a particular substance present in a sample had to analyze the sample via a series of chemical reactions specific to that species and then carefully weigh the products. Today, most routine assaying is done quickly and efficiently by means of spectroscopy.
    • 14A: Atomic Emission Spectra (Experiment)
      Electrons in atoms normally occupy the lowest energy states possible. Such an atom is said to be in the ground state. However, electrons can be excited to high energy states when they absorb excess energy. The excess energy can be provided by heat, light, or electrical discharge. The electrons then return to lower energy states, eventually returning all the way to the ground state. As the electrons return to lower energy states, they release their excess energy, often, in the form of light.
    • 14B: Atomic Emissions Spectra - Pizza Box Version (Experiment)
      Electrons in atoms normally occupy the lowest energy states possible. Such an atom is said to be in the ground state. However, electrons can be excited to high energy states when they absorb energy. This energy can be provided by heat, light, or an electrical discharge. The electrons will then return to lower energy states, eventually returning all the way to the ground state. As the electrons return to lower energy states, they release their excess energy, often in the form of light.
    • 15: Using Periodic Properties to Identify Group 2A Cations and Group 7A Anions (Experiment)
      When the solubilities of compounds containing various cations combined with a given anion are compared, a solubility trend that follows the order in the periodic table is expected. For example, for the solubilities of the sulfate salts, the solubility is expected either to increase or decrease as we go down the alkaline earth family. These solubility properties will be used to identify an unknown compound containing a cation.
    • 16: Qualitative Analysis of Everyday Chemicals (Experiment)
      This lab introduces qualitative analysis, the area of chemistry concerned with the identification of substances by their physical and chemical properties. Identifying unknown substances is an important part of chemistry, with applications in fields such as medicine and environmental chemistry. Materials can be characterized by observing their physical and chemical properties and/or by instrumental methods.
    • 17: VSEPR Theory and Shapes of Molecules (Experiment)
      The VSEPR (Valence Shell Electron Pair Repulsion) model is used to predict the geometry of molecules based on the number of effective electron pairs around a central atom. The main postulate for the VSEPR theory is that the geometrical structure around a given atom is principally determined by minimizing the repulsion between effective electron pairs. Both the molecular geometry and the polarity of individual bonds then determine whether the molecule is polar or not.
    • 18: Introduction to the Structures and Isomerism of Simple Organic Molecules- Description and Modeling (Experiment)
      Molecules that have the same molecular formula but are not identical are called conformers or isomers. Conformers differ only by the angle of rotation about a single bond(s) however isomers have different structural or spatial arrangements.