1) Jeffrey Cox CHE111-DL01 Lab number 10 Stoichiometry of a Precipitation Reaction 2) Purpose/ Intro. In this lab we will be able to calculate the actual, theoretical, and percent yield of the product from a precipitation reaction. We will thusly learn the concepts of solubility and the formation of a precipitate. A precipitate reaction is a reaction in which soluble ions in separate solutions are mixed together to form an insoluble compound that settles out of the combined solution as a solid. The solid then is the insoluble compound, called a precipitate.
A) Stoichiometry allows prediction of the amounts of products that form in a chemical reaction based on the amounts of reactants. B) Stoichiometry allows prediction of how much of the reactants are necessary to form a given amount of product. C) Stoichiometry shows the numerical relationship between chemical quantities in a balanced chemical equation. D) All of the above are true. E) None of the above are true.
Each of these types of reactions behaves in a similar fashion. They all involve the conversion of one substance to another substance, while preserving the original elements in some form. Another aspect of predicting products is the chart of reactivity. In order for the replacement of an element in a compound to happen, the element replacing the original element must be more reactive. The chart of reactivity tells chemists the comparable reactivity of elements.
Which property in Table 2.1 can most easily distinguish sodium chloride from the other solids? The property in Table 2.1 that most easily distinguishes sodium chloride from the other solids is its color. 7. Is the freezing of mercury a reversible or irreversible physical change? Explain your answer.
For this particular exercise, you should be familiar with the following: • Sublimation: Many chemicals will sublime (phase change from solid state to gas state) provided the right conditions. Iodine, for example, sublimes at room temperature. A bottle of iodine will thus always have crystals forming around inside the bottle around the cap where sublimed iodine is being deposited (phase change from gas state back to solid state). Provided the proper equipment, chemicals that are being sublimed can be recovered. Decant(ing): Decanting is a way of separating a solid from a liquid.
For example, water (H2O) has a melting point of 320 F, and a boiling point of 2110 F. (Properties of water, 2012) A compound can have different properties than the original compound. A new substance is actually formed when constituents are chemically combined and can only be separated by chemical means. (What is the difference between a compound and a mixture?, 2012) Two or more compounds can make up an element, which is a single substance from the periodic table. IE: Hydrogen, Carbon, Oxygen and Potassium would be a compound where H2O (One oxygen and two hydrogen atoms) would be an element. In contrast, mixtures are impure substances and can be made up of different compounds.
Why is it important to determine these physical properties of a substance? The melting point of a solid is the point at which a solid becomes a liquid with standard atmospheric pressure. The boiling point of a liquid equals the external pressure. It is important to know these characteristics of a substance so that you can handle them in the correct manner. The boiling point and melting point can also be used to identify an unknown substance.
CHROMATOGRAPHIC METHODS: After successful extraction of phospholipids from their source analysis can be performed for the detection of specific phospholipids. This section will discuss chromatographic methods used for the analysis of phospholipids. All systems of chromatography consist of a stationary and mobile phase. A monster placed on a stationary phase, i.e., a solid or a liquid, and the mobile phase, a gas or a liquid, is allowed by modifying the system. The components of the sample will be separated on the basis of their ranging physical and chemical properties, imparting different affinities for the two phases.
EXPERIMENT 6 Title Kinetics of Chemical Reaction – Iodination of Cyclohexanone Aim To determine the value of the rate constant, k and order of reaction, a, b and c, and also to suggest a mechanism which agrees with the rate equation that has been obtained. Background Theory The basis of the theory of absorbance is as follows: Io ―――――→ sample ―――――→I if Io = I, no absorbance occur Io > I, the sample absorbs certain amount of light wave Io < I, the sample emits certain amount of light of certain wave length. THE HALOGENATION (IODINATION) OF KETONES (CYCLOHEXANONE) This experiment examined the rate of iodination of cyclohexanone in an aqueous medium. To increase the amount of iodine in the solution, iodine is converted to a more soluble complex ion, I3- by the addition of excess iodide ion: I2 + I- →I3- One of the characteristic reactions of ketones is the substitution of a halogen for one of the hydrogen is adjacent to the ketone group. The net reaction is: This reaction has been studied extensively and occurs for a wide variety of ketones.
Observations of Chemical Changes Purpose: To examine the reactions of chemicals and see what types of changes can occur. Procedure: I used a 96-well plate and the following chemicals to document the chemical changes that occur: Ammonia, Bromthymol Blue, Copper (II) Sulfate, FDC Blue dye #-1, Hydrochloric Acid, Lead (II) Nitrate, Phenolphthalein Solution, Silver Nitrate, Sodium Bicarbonate, Sodium Hydroxide, Sodium Hypochlorite, and Starch Solution. Data Tables: Well #/Question | Chemicals | Reaction | A | NaHCO3 and HCl – CO2 | Bubbles formed | B | HCl and BTB | Turns a yellow/orange color | C | NH3 and BTB | Turned to orange | D | HCl and Blue Dye | Turns green | E | Blue Dye and NaOCL | Stayed blue | F | Kl and Pb(NO3)2 |