Lab 1_ Separation of Liquids by Distillation Procedure (1)

A sample (50 mL) of a bottled water was added to a 100 mL volumetric flask and then diluted to the mark. From this stock solution, 50 mL was taken, added to a 100 mL volumetric flask and diluted to the mark. Final concentration of the serial dilution: 587.7161ppm. 1. what is the concentration in the original bottle (ppm)

You obtain an Unknown Sample from the Stockroom.  You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file.  You first add HCl and centrifuge your mixture.  You observe the formation of a white precipitate in the bottom of the test tube.   After pouring off the supernatant liquid, you add hot water to the white precipitate.  Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube.   Which of the following is a valid conclusion to draw at this point?     Pb2+ is definitely present.   Hg22+ is definitely present.   Ag+ could be present, or Hg22+ could be present, or BOTH could be present.   Ag+ is definitely present

You obtain an Unknown Sample from the Stockroom.  You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file.  You first add HCl and centrifuge your mixture.  You observe the formation of a white precipitate in the bottom of the test tube.   After pouring off the supernatant liquid, you add hot water to the white precipitate.  Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube.  You pour off the supernatant liquid, and add ammonia (NH3) to the remaining precipitate.  You now observe the formation of a gray-black precipitate. Which of the following is a valid conclusion to draw at this point? Select one:     Hg22+ is definitely present.   Pb2+ is definitely present.   Ag+ could be present, or Hg22+ could be present, or BOTH could be present.   Ag+ is definitely present

Data Sheet 4 ble gives the recommended mass of salt to dissolve in each of the four test tubes. Show a sample calculation for the solubility of KNO, using your actual mass from tube #1. Complete your graph on the back of this sheet. Solution # Recommended mass KNO3 Actual mass of KNO, (g per 5 mL H₂O) Solubility & KNO, 100 g H₂O Saturation temperature (°C) (g) 1 2.0 51.3 2.1971 2 62.5 4.0 11.1568 3 72.7 6.0 6.0112 83.6 4 8.0 806 Sample Solubility Calculation: Questions 1. According to your data, how does the solubility of KNO, change with increasing temperature? Does this indicate an endothermic or exothermic dissolving process? Explain. 2. Using your graph, indicate if each of these solutions would be saturated or unsaturated: a) 110 g of KNO3 in 100 g of water at 40 °C b) 60 g of KNO3 in 100 g of water at 70 °C c) 140 g of KNO3 in 100 g of water at 60 °C 3. According to your graph, what mass of KNO3 will dissolve in 100 g of water at 30 °C?

Consider the following scenario: You obtain an Unknown Sample from the Stockroom.  You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file.  You first add HCl and centrifuge your mixture.  You observe the formation of a white precipitate in the bottom of the test tube.   After pouring off the supernatant liquid, you add hot water to the white precipitate.  Addition of the hot water dissolves some of the precipitate, but some white precipitate still remains on the bottom of the test tube.  You pour off the supernatant liquid, and add ammonia (NH3) to the remaining precipitate.  You now observe the formation of a gray-black precipitate. Which of the following is a valid conclusion to draw at this point? Select one:   1. Hg22+ is definitely present.   2. Pb2+ is definitely present.   3. Ag+ could be present, or Hg22+ could be present, or BOTH could be present. 4. Ag+ is definitely present

Solution 1 Solution 2 Solution 3 Solution 4 Solution 5 Concentration iron(III) nitrate 0.00200 0.00200 0.00200 0.00200 0.00200 [Fe(NO3)3] (M) Concentration potassium thiocyanate 0.00200 0.00200 0.00200 0.00200 0.00200 [KSCN] (M) Volume Fe(NO3)3 (mL) 5.00 5.00 5.00 5.00 5.00 Volume KSCN (mL) 5.00 4.00 3.00 2.00 1.00 Volume DI water (mL) 0.00 1.00 2.00 3.00 4.00 Initial concentration [Fe3+] (M) 0.00100 0.00100 0.00100 0.00100 0.00100 Initial concentration [SCN‍] (M) 0.00100 0.000800 0.000600 0.000400 0.000200 Absorbance 0.269 0.192 0.154 0.104 0.052 Equilibrium [FeSCN2+] (M) 0.000198 0.000141 0.000113 0.0000765 0.000038 Equilibrium constant Kc Average Kc

5. Why is decantation rather than filtration the preferred method of separating the salt from the mixture? 12:03 AM

Assume we are to tackle a complex aqueous equilibria problem using the systematic process we learned in class.  In our example, we’re going to look at dissolving silver chromate (Ag2CrO4, Ksp = 1.2 x 10–12) in water.  Write 1 mass balance equation.

please highlight the correct answer

What are the types of gravimetric methods? Give an examples where each method is used in an analysis. What is particulate gravimetry? When do we use this technique?

Construct the expression for Kc for the following reaction. 1 3NO(g) = N20(g) + NO2(g) Construct the expression for Kc for the following reaction. 2 X 4HCI(aq) + O2(g) = 2H20(1) + 2C12(g) > Construct the expression for Kc for the following reaction. 3 CH4(g) + 2H2S(g) = CS2(g) + 4H2(g) Construct the expression for Kc for the following reaction. 4 X 2Cu*(aq) + Zn(s) = 2Cu(s) + Zn²*(aq) >

You obtain an Unknown Sample from the Stockroom.  You begin testing the solution through the steps outlined in the flowchart of the experiment’s PDF file.  You first add HCl and centrifuge your mixture.  You observe the formation of a white precipitate in the bottom of the test tube.   After pouring off the supernatant liquid, you add hot water to the white precipitate.  Upon addition of the hot water, you have some white precipitate still at the bottom of the test tube, and the supernatant liquid is poured off.  To this liquid, potassium chromate (K2CrO4) is added.  Upon this addition of potassium chromate, you observe no formation of precipitate. Which of the following is a valid conclusion to draw at this point? (Choose one.)   Select one:   1. Hg22+ is definitely present.   2. Pb2+ is NOT present. 3. Ag+ is definitely present. 4. Pb2+ is definitely present.

A student wants to determine how different factors affect the rate of dissolving a solid in water. The student will test: the size of the particles, the temperature of the water and the amount of agitation or stirring. Investigation Particle size Temperature (°C) Stirring small 59 yes small 38 yes 3 small 60 yes Which investigation will have the slowest rate of dissolving and why? Use evidence to explain your answer.

POST-LABORATORY QUESTIONS Due after Laboratory Experiment 1. What is the equation for the dehydration of CuSO4 · 5H20? 2. A student dehydrated a sample of hydrate incompletely. Explain how the incomplete dehydration of the hydrate affects the calculation of the percent of water of hydration. What should the student do? 3. To the cooled anhydrate, CUSO4, of Part I, a student added about 5 mL of distilled water and then stirred the mixture with a stirring rod. When the student carefully touched the outside of the evaporating dish, do you expect the student to feel hot of cold? Is the rehydration an exothermic or endothermic process? 4. A student had a sample of CaCl2 • nH2O. He heated the sample until the mass did not change. From this data, calculate (a). the percentage of CaCl2 in the original sample and (b). the formula of the hydrate NOT ROUND Mass of crucible + cover = 28.39 g T Mass of crucible + cover + sample = 30.41g Mass of crucible + cover + residue = 29.75 5. The chemical…

In this experiment you will measure the enthalpy of three processes. Reaction 1 NaOH (s) → NaOH (aq) AH1 Reaction 2 NaOH (aq) + HCI (aq) → H2O (I) + NaCI (aq) AH2 Reaction 3 NaOH (s) + HCI (aq) → H2O (I) + NaCI (aq) AH3

Calculate the solubility of Ni (OH)₂ in water at 25 °C. You'll find Ksp data in the ALEKS Data tab. Round your answer to 2 significant digits. 60 A x10 X 5

How do fill in the Flow Diagram for the Mixtures using the information presented?