Exam ALL ANSWERS 100% CORRECT SPRING FALL-2022/2023 SOLUTION GUARANTEED GRADE A+

Which is NOT an indicator of a chemical change? - State of matter changes. In an exothermic reaction, the products have _____. - less energy than the reactants When hydrochloric acid reacts with potassium hydroxide solution, the following reaction occurs. HCl (aq) + KOH (aq) H2O (l) + KCl (aq) The reaction gives off heat energy, so it is an reaction. - exothermic Use the standard enthalpies of formation for the reactants and products to solve for the ΔHrxn for the following reaction. (The ΔHf of Ca(OH)2 is -986.09 kJ/mol and liquid H2O is -285.8 kJ/mol.) Ca(s) + 2H2O(l) Ca(OH)2 (s) + H2(g) ΔHrxn = The reaction is . - -414.4 kJ exothermic Given the chemical equation, predict the ΔSsystem for this change. O2 (g) O2 (aq) - -ΔS Choose whether the process below is spontaneous or not spontaneous. Salt dissolves in water. - spontaneous Calculate the ΔG for the following system. Then state if the system is spontaneous or not spontaneous. ΔH = + 25 kJ ΔS = +5.0 J/K T = 23°C - +24 kJ; not spontaneous What is the molarity of an aqueous solution that contains 12.2 grams of SrCl2 dissolved in 2,500 milliliters of solution? - 0.031 M If two gases react, compressing the gases generally the rate of reaction. - increases An experiment is conducted using nitrogen monoxide and bromine reacted to form nitrosyl bromide. Calculate Keq for the reaction using the following equation data. [NOBr] = 0.0474 mol/L [NO] = 0.312 mol/L [Br2] = 0.259 mol/L Keq = - 0.0891 What is the molecular weight (mass) for KOH? - 56.10 g/mol Calculate the number of molecules present in 3.50 mol FeO2. - 2.11 x 1024 molecules If a chemist wants to make 1.3 L of 0.25 M solution of KOH by diluting a stock solution of 0.675 M KOH, how many milliliters of the stock solution would the chemist need to use? - 480 mL Answer the questions about the following reaction. 4Al(s) + 3O2(g) 2Al2O3 (s) How many molecules of O2 are used in the reaction? How many oxygen atoms are required? How many moles of Al2O3 are formed? What is the mole ratio of Al to O2? - 3 6 2 4/3 How many moles are present in 10.5 grams of NaCl? - 0.180 mol Balance the reaction which forms ions. Choose "blank" if no coefficient other than 1 is needed. Pb(N03)2(aq) Pb+2 + NO3 - - blank 2 Substance A dissolves in water. What can be said about substance A? - It is polar. A solution has a Pb2+ concentration of 1.9 x 10-3 M, and an F-1 concentration of 3.8 x 10-3 M. The value of Ksp for PbF2 at room temperature is 4 x 10-8. Will this solution form a precipitate? The solubility equilibrium equation is as follows. - no