Determine the amount of water of crystallization of sodium carbonate from a bottle containing anhydrous sodium carbonate which was left uncovered and labeled T1. Sodium carbonate (Na2CO3) coded T1 with unknown concentration; solution T2 containing 3.65 g of hydrochloric acid (HCl) in 1 dm3 and MO methyl orange indicator. Measure 10 cm3 of T1 and dilute it with distilled water up to 150 cm3 in a volumetric flask. Transfer the resulting solution into a beaker provided then pipette 20.00 cm3 (or 25.00 cm3) of the obtained solution and then transfer the pipetted solution into a conical flask. Procedures: Titrate T2 (from the burette), against T1 (in the titration flask) using MO until the end point. Record the results including one rough and three accurate titrations in a tabular form.

1. Present your results in an appropriate tabular form. (0 alama)
2. Why a burette and a pipette must be rinsed with the solution which they are to be filled with? (0 alama)
3. Why a titrating flask should not be rinsed with the solution which they are to be filled with? (0 alama)
4. Calculate the concentration of T1 in mol dm-3. (0 alama)
5. Calculate the concentration of diluted T1 in mol/dm3. (0 alama)
6. Determine “X” in Na2CO3·XH2O if the diluted 10 cm3 solution contains 2.145 g of hydrated sodium carbonate. (0 alama)

Boresha ili kuona majibu ya mfano.

Students were debating about the heat of reaction when dissolving anhydrous copper(II) sulphate and hydrated sodium thiosulphate in water. The argument was whether such reaction releases or absorbs heat. You are consulted to help to find the correct answer for their debate. In the process of undertaking the task, you are required to use the following: R1: Anhydrous copper (II) sulphate (CuSO₄); R2: Hydrated sodium thiosulphate (Na₂S₂O₃.5H₂O); Distilled water, thermometer, plastic beaker (100 cm³), 100 cm³ measuring cylinder and a stopwatch. Perform the experiment through the activities in the procedure and then answer the questions that follow. Procedure (i) Measure 50 cm³ of distilled water and transfer it in the plastic beaker. Record the initial temperature in degree centigrade as T initial. (ii) Weigh 4.0 g of R1 and transfer the salt into the measured water in (i) and immediately start a stopwatch while stirring gently the mixture with a thermometer. (iii) Record the temperature in every 1-minute time interval five times. (iv) Clean and dry the beaker ready for the second experiment. (v) Repeat step (i) to (iii) except that instead of 4.0 g of R1 in step (ii), use 6.0 g of R2. (vi) Record temperature in 1-minute time interval five times.

1. Draw and fill the results in the appropriate table. (0 alama)
2. Plot the graphs of temperature as a function of time for both CuSO₄ and Na₂S₂O₃.5H₂O solutions in the same graph axes and show the final temperature attained for each reaction. (0 alama)
3. State which salt caused exothermic or endothermic reaction among the two salts. Support your answer with a reason. (0 alama)
4. Calculate the heat change for each process using the following constants: Density of water = 1 g/cm³ Specific heat capacity of water (cp) = 4.2 J g⁻¹ ºC⁻¹ (0 alama)

Boresha ili kuona majibu ya mfano.

The sample salt was brought to your college as sample R. Perform a systematic qualitative analysis experiment to identify the cation and the anion present in the sample. Base your experiment on the listed tests and then answer the questions that follow: (i) Appearance of sample R (ii) Action of heat on sample R in a test tube (iii) Action of dilute sulphuric acid on the solid sample (iv) Action of concentrated sulphuric acid on solid sample (v) Flame test (vi) Solubility of the sample (vii) Confirmatory test for the anion (viii) Confirmatory test for the cation

1. Prepare a relevant Table showing the analysis results. (0 alama)
2. What are the cation and anion present in the sample? (0 alama)
3. Write the reaction equation to indicate what took place in test (iv). (0 alama)

Boresha ili kuona majibu ya mfano.