Chem 112 Assignment for Chapter 19 1. Calculate ΔS° values for the following reactions by using tabulated S° values from Appendix B (Petrucci text) a) N2H4 (g) + H2 (g) → 2NH3 (g) b) 2Al (s) + 3 Cl2 (g) → 2 AlCl3 (s) c) Mg(OH)2 (s) + 2 HCl (g) → MgCl2 (s) + 2 H2O (l) d) 2 CH4 (g) → C2H6 (g) + H2 (g) 2. Use data in your Appendix B to find ΔH° and ΔS° values at 25°C to calculate ΔG° where ΔG° = ΔH° - T ΔS° for each of the following reactions. a) Ni (s) + Cl2 (g) → NiCl2 (s) b) CaCO3 (s, calcite) → CaO (s) + CO2 (g) c) P4O10 (s) + 6 H2O (l) → 4 H3PO4 (aq) d) 2 CH3OH (l) + 3 O2 (g) → 2 CO2 (g) + 4 H2O (l) Note: the following values ΔHf° (kJ/mol) S° (J/K) Ni (s) 0 29.9 NiCl2
Students are merely learning how to collect data and record. Students are also learning inquiry-based techniques. The next three levels are progressively less teacher oriented and more student oriented. During the structured inquiry students are presented with the question and procedure, but students must formulate the results. During guided inquiry students are provided with only the research question.
==> NaHCO3(aq.) + NaCl(aq.) We will standardize the HCl solution to use it in the titration. The standardization will come as a result of the 1:1 molar ratio above. Thus, the molarity of the HCl solution can be calculated by dividing the number of moles of HCl by the volume of HCl (in liters) used to neutralize the Na2CO3 .
Pour the contents of one of the test tubes into the other and a reaction should occur and you should see a white precipitate of barium sulfate form. Then, centrifuge it for 1 minute. On the side, weight a boiling test tube containing 2 boiling chips. When the separation is complete, remove the small test tubes from the centrifuge and decant the supernatant into the boiling test tube. Add 1 mL of deionized water to the small test tube containing the precipitate and mix it and centrifuge it for 60 seconds.
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.
-We measured in each chemical and added water besides, HCl we added NaOH. Next, we measured the water temperature to begin with then added the substance to it to determine the finally temperature. We minus the initial and finally to decide if the reaction is exothermic and endothermic. 5. Describe the anticipated temperature change of a system in which an exothermic process is taking place.
93 g/mol? Not we get to use it! Yay! 93 g/mol / 31.06 g/mol = 3 (this is the multiplier) Multiply that whole number through the subscripts of the empirical formula. 3 x (C H5 N) = C3H15N3 Hydrated compounds Solving process: 1st- the difference between the initial mass and that of the dry sample is the mass of water that was driven off.
Experimental First, we weighed 2 samples, each has 1 gram of NaHCO3-KCl mixture Second, we put the samples in 2 crucibles (A and B) and weighed them. (crucible + sample; WA1 and WB1) Third, we heated both samples on a hot plate for 30 minutes. Fourth, we weighed the samples again (crucible + sample; WA2 and WB2) Lastly, we determined NaHCU3 percentage in the mixture using the following method: WA1 – WA2 x 100% 0.309 WA1 – WA2 x 100% 0.309 * * Results * Theorectically: * Discussion When sodium hydrogen carbonate is heated, new products are formed; sodium carbonate, water vapor, and carbon dioxide gas. This reaction may be presented in a different form with a measure of molecules: @Na2CO3 + H2O + CO2 (solid) (solid) (gas) (gas). Once the reaction of sodium hydrogen carbonate takes place, carbon dioxide gas is released, as well as water vapor.
Therefore the alkalinity of water samples is being calculated. In the second approach, the two volume readings for the respective amounts of sulfuric acid used are being determined an indicator based method. Congo red and bromocresol green are being used as the indicators. Procedure (Outline provided as pre-lab): A. The pH meter was calibrated using standard pH solutions provided.
How do you go from calculated/measured values to accomplishing stated purpose? (4 pts) The purpose of this lab is to determine the exact concentration of an unknown acetic acid solution. Titrations for two different reactions will be performed. Controlled volumes of one reagent are added to a flask containing the other reagent until the equivalence point of the reaction is reached, one between sodium hydroxide (NaOH) and potassium hydrogen phthalate (KHP) and the other between NaOH and acetic acid (CH3COOH). NaOH (aq) + KHP (aq) —› Na+ (aq) + K + (aq) + P2- (aq) + H2O (l) NaOH (aq) + CH3COOH (aq) —› Na+ (aq) + CH3COO- (aq) + H2O (l) The titration of NaOH with KHP will identify the concentration of the NaOH provided.