Calculations involving the Mole, Avogadro’s Number, Molar Mass, Mole-Mole and Mass-Mole calculations in chemical equations. Combustion analysis and calculation of empirical and molecular formulas from composition analysis. Electrolytes and non-electrolytes. Precipitation reactions and solubility rules. Writing balanced molecular equations and net ionic equations.
Chapter Two: Freezing Point Depression Measurements Purpose: The purpose of this lab is to measure freezing points and freezing point depression for several solutions. The freezing point depression constant (Kf) for p-xylene was calculated from freezing point measurements and used to estimate the molar masses of three unknown solutes in a p-xylene solution. The end goal of this lab experiment is to correctly identify these three unknown solutes. The molar mass of a solute is able to be determined through freezing point depression measurements because the increase in solutes disrupts crystal formation, requiring a lower temperature to form a lattice. This colligative property is important in many industries, but is clear to see when using ordinary salt to remove ice from steps or a driveway.
The first example is calculating empirical formulas from percent compositions using the percents of the different elements. Empirical formulas of compounds are also determined through quantitative analysis by using the masses of each element in the equation3. Lastly, this experiment uses the method of finding empirical formulas through combustion analysis. The empirical formula of magnesium oxide is found from the combustion of magnesium1. The four chemical equations that result when metal magnesium is heated in a closed crucible that becomes gradually exposed to the oxygen in the air are shown in table
Predict the number of valence electrons for a sulfur atom. a. 4 b. 6 c. 8 d. 16 e. 32 58. Predict the number of valence electrons for a chlorine atom.
+6.7 C. –2680 D. +2680 3. Which of the following chlorides is likely to have the most ionic character? A. LiCl B. CsCl C. BeCl2 D. CaCl2 4. Which equation represents the first ionisation energy of a diatomic element, X2? A.
In this experiment, you will make an experimental determination of the molar volume. The basis of this experiment is the following reaction in which you will react a known mass of magnesium with excess hydrochloric acid to produce the substances shown: Mg(s) + 2HCl(aq) ( MgCl2(aq) + H2 (g) The hydrogen gas is the product that is of interest to you in this experiment. You will make an experimental determination of the number of moles of hydrogen molecules produced and the volume occupied by these molecules. The number of moles of hydrogen will be determined indirectly. The balanced equations for this reaction shows that the molar ratio of magnesium reacted to hydrogen gas produced is 1:1.
Use a calorimeter to measure the temperature change in each of three reactions. Calculate the heat of reaction, ∆H, for the three reactions. Use the results to confirm Hess’s law. Ev al Figure 1 ua tio Na+(aq) + OH–(aq) + H+(aq) ) + Cl–(aq) → H2O(l) + Na+(aq) + Cl–(aq) ∆H3 = ? n (3) Solutions of aqueous sodium hydroxide and hydrochloric acid react to form water and aqueous sodium chloride.
Chlorine gas can be produced in the laboratory by adding concentrated hydrochloric acid to manganese(IV) oxide in the following reaction: MnO2(s) + 4HCl(aq) ( MnCl2(aq) + 2H2O(l) + Cl2(g) a. Calculate the mass of MnO2 needed to produce 25.0 g Of Cl2 ans: 30.7 g MnO2 b. What mass of MnCl2 is produced when 0.091 g of C12 is generated? ans: 0.16 g MnCl2 1. How many moles of ammonium sulfate can be made from the reaction of 30.0 mol of NH3 with H2SO4 according to the following equation: ans.
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.
Lab #09: Is the Substance Ionic or Covalent? Purpose: To identify compounds as ionic or covalent based on their properties. We will do this by testing melting point, conductivity, and solubility. Hypothesis: Draw a chart in which you will predict what your results will look like for the three different tests for an ionic compound and a covalent compound. We will fill this table in