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CHILDREN S PALACE

CHILDREN S PALACE . WATER, THE MOST COMMON SOLVENT. The level of the learner: Students in the 7 th , 8 th , and 9 th grade Theoretical notions necessary for successful completion of this unit learning: Ways of expressing the concentration of solutions Types of chemical reactions.

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CHILDREN S PALACE

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  1. CHILDREN S PALACE WATER, THE MOST COMMON SOLVENT

  2. The level of the learner: • Students in the 7th, 8th, and 9th grade • Theoretical notions necessary for successful completion of this unit learning: • Ways of expressing the concentration of solutions • Types of chemical reactions

  3. What skills you will acquire: • You will explain the procedures, processes, phenomena encountered in daily life • You will investigate the behaviour of certain substances or chemical systems • You will solve various numerical applications in order to establish the relevant correlations, demonstrating deductive and inductive reasonings • You will assess the consequences and the action of chemical processes on your own person and the environment

  4. Contents: • Aqueous solutions used in everyday life • Aqueous solutions used in laboratory practice. Chemical reactions in aqueous solutions • Body solutions and their physiological significance • Water in the vegetable kingdom.

  5. 1. AQUEOUS SOLUTIONS USED IN EVERYDAY LIFE

  6. The solution of salt kitchen • A solution of sodium chloride infusion (physiological serum used in medicine) has a density of 1, 11 g/ml and contains 0, 9 g NaCl per 100 ml distilled water. Other salt solutions, more concentrated are used for food preservation.

  7. The solutions of glucose administered for therapeutic purposes provide the energy necessary to normal function of the cells; improves the trophicity of the liver by protecting it from various pollutants; improves myocardial function, balances blood pressure etc. Hospitals frequently use ampoules of injectable glucose concentration 5%, 25%, respectively, of the concentration of glucose 33%.

  8. A solution obtained by dissolving 0,5 kg bluestone in 100 kg of water is used in the treatment of seed wheat against mălurii (a microscopic fungus) and disinfection of seeds of tomato, pepper, eggplant, carrots etc. “zeamabordeleză” also well - known is used for sprinkling the vinery against the manna (Plasmopora wine-growing fungus) which is obtained by dissolving 1 kg of bluestone with 0.5 kg of varnestins per 100 kg.

  9. Fertilizer solutions for plants • Rhombic crystals of CuSO4.5H2O, obtained by slow cooling of a saturated solution of copper sulphate • Fertilizer label used for apartment plants generally indicates a content of 5% ammonium nitrate (5 grams of ammonium nitrate fertilizer in 100 ml fertilizer). As a rule, azot is supplied by ammonium nitrate, the most common source of azot in the trade fertilizer, Rhombic crystals of CuSO4.5H2O, obtained by slow cooling of a saturated solution of copper sulphate

  10. PRACTICAL LEARNING ACTIVITIES: • Practical preparation of a solution of a certain percentage concentrations

  11. 1. A solution of sodium chloride infusion (physiological serum used in medicine) has a density of 1, 11 g/ml and contains 0, 9 g NaCl per 100 ml distilled water • calculate percentage concentration of physiological serum • prepare 0,05 l physiological serum • You have on work table: • -reagents: sodium chloride, distilled water • -utensils: scales, set of weights, balance, Berzelius glass, watch glass, 50 ml volumetricflask • Browse through the following steps carefully in order to achieve a correct preparation:

  12. Step 1 Calculate the amount of salt you will weigh • Step 2Weigh sodium chloridewhilerespecting the followingrules in the weighing: • ! balance the scales • ! weigh a watch glass; place the watch glass on the left plate of the scale and on the right plate add the appropriateweightsuntilrelevel the scales • ! add to the right-hand plate weights corresponding to the quantity of salt • ! add salt until re-level the scales • Step 3 Add salt into a Berzelius glass and dissolve it in 10-15 ml of distilled water • Step 4 Add the solution obtained in 50 ml volumetric flask and bring up to volume sign with distilled water (pay attention to the measurement of liquids: the reading is made at a lower meniscus) • Step 5 show to your teacher the solution prepared.

  13. 2. Select the reagents and the necessary utensils from the work table and prepare 100 ml solution of copper sulfate (bluestone) of 2% concentration. The density of the solution is 1, 2 g/ml. • Use the following guidelines for a successful preparation: • Step 1 calculate by applying the formula of density your solution the mass –ms • Step 2 replace in the concentration formula and calculate the mass of coppersulphate -md • Step 3weigh md • Step 4add md in a Berzelius glass • Step 5 calculate mass of water needed for your solution

  14. Step 6 calculate the volume of water required for your solution • Step 7measure the volume of distilled water, addit over the coppersulphate in the glass • Step 8shakewith a wand, note on a label the prepared solution and its concentration and stick it on the glass.

  15. ASSESS YOURSELF: • Solving numerical applications/ Percentage concentration of solutions/ Dilution of solutions/ Concentration of solutions/Rectangle Rule

  16. 1. Mix 200 g HNO3 concentration solution 63%, with 400 g HNO3 solution concentration of 31.5%. In the final solution of HNO3 are found: • a) 4 moles HNO3; • b) 348 cm3 H2O; • c) 2,4088∙1024 molecules of HNO3. • 2. A solution will take a percentage of 50% concentration, if: • a) dissolve 100 g of salt in 100 g water • b) to 200 g of 25% solution add 240 g water; • c) to 400 g 80% solution add 240 g water; • 3. Physiological serum is a 0.83% NaCl solution. If a person is injected 20g physiological serum , in the body there are introduced: • a) 0,166 g salt; • b) 19,834 g water; • c) 0,83 g salt.

  17. 4. To 150 cm3 soil of sulphuric acid, H2SO4 18% concentration, with a density of 1,12g/cm3 add 4g of sulfuric acid, H2SO4. The percentage concentration of the final solution is: • a) 19,9% • b) 1,99% • c) 20,38% • 5. 50 g solution acid azotic, HNO3, 60% concentration, diluted with distilled water until the solution becomes 20% concentration. What is the ratio of mixing of the two liquids? • a) 1:3 • b) 1:4 • c) 1:2

  18. 6. What amount of sulphuric acid solution, H2SO4 80% concentration must be added over 4 Kg of sulphuric acid solution, H2SO4 40% to get a 50% concentration solution? • a) 4,88kg sulphuric acid solution, H2SO4 concentration 80% • b) 4880g sulphuric acid solution, H2SO4 80% concentration • c) 4880mg sulphuric acid solution, H2SO4 80% concentration

  19. 7. 50 g of HCl solution reacts completely with 150 g of silver nitrate solution. • a) Knowing that the resulting acid solution has a concentration 10%, the initial concentrations of the two solutions are 18,88%, respectively 29,31% • b) the importance of the chemical reaction is the identification of anionului azotat, NO3-; • c)experimental observation is getting a cheesy white precipitate silver chloride, soluble in concentrated ammonia solution.

  20. INFOPLUS! • Identification of ammonium nitrate in nutrient solutions for plants in trade

  21. As a rule, azotul is supplied by ammonium nitrate, the most common source of nitrogen in the manure for trade. The presence of ammonium nitrate in a manure for plants can be checked by the following experiment: • Step 1 Solubilizing sample • If we buy a solid fertilizer we first make a sample of solubility: dissolve about one gram of manure in 10 ml of water in a test tube

  22. Step 2 The identification of ionuluiazotat • Over 5 ml solution of fertilizer solution add 5 drops of sulphuric acid, H2SO4 concentration and a few copper pieces şpancupru (or copper powder). Our fertilizer contains nitrates because after 5 minutes the solution became blue and it was noticed emission of nitrogen dioxide, NO2, brown gas with specific irritating smell. • 2NH4NO3 + H2SO4 = 2HNO3 + (NH4)2SO4 • 8HNO3 + 3Cu = 3Cu(NO3)2 + 2NO↑ + 4H2O • NO + 1/2O2 = NO2↑

  23. Step 3 The identification of ionuluiamoniu • Over 5 ml solution fertilizer add 5 ml of NaOH 30%; cover the tube’s mouth with a swab soaked in solution of phenolphthalein; our fertilizer contains ammonium nitrate because shortly the swab becomes carmine red (presence of a base) and it feels pungent odor of ammonia, in accordance with the chemical reaction equation below: • NH4NO3 + NaOH= NH4OH + NaNO3

  24. EXPERIMENTAL TOPICS Spectacular behaviour of sodium silicate solution to addition of some salts

  25. Workflow • Place metal salts crystals of different colors in a sodium silicate solution, avoiding as far as possible their clutter. I used medium-sized crystals, as well as more compact: CuSO4·5H2O blue, Ni(NO3)2 green, NiCl2·6H2O light green, FeCl3 brown – yellow, CoCl2 · 6H2O red-violet, MnSO4 · 4H2O pale pink, CrCl3 dark green, KAl(SO4)2 · 12 H2O white, FeSO4 · 7H2O greenish white.

  26. Observations and explanation of the phenomenon • As soon as they get into the solution of silicate, metal salts are dissolved in water, and the metal ions Cu2+, Fe3+, Ni2+, Co2+, Mn2+ form, in contact with silicate ions SiO32- a solid membrane around the initial crystal. “The cell” was born. The created membrane is semi - permeable, only allowing the water to pass. This way it demarcates the two solutions: the internal one, which contains only dissolved metal salt, and the external containing only sodium silicate. This compositional difference leads to an influx of water from the outside to the inside, due to the phenomenon of osmosis (actually used by Leduc in comparing this “cell” with a living one). The ingress of water induces an increase in internal pressure, followed by breaking the membrane and its restoration, resulting in an increasing tree shape.

  27. Obs. The air bubbles “hung” by the placed crystals supports the growth upwards.

  28. The glass should be covered and this way the solution can be kept for longer time. The carbon dioxide present in the air disturbs the solution; After about an hour, the rods are stiff, but with time, they may break

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