LET’S START WITH COPPER CHEMISTRY REPORT 2012 INTRODUCTION: The law of conservation of mass means that the atoms of an object cannot be created or destroyed, but can be moved around and be changed into different particles. This law says that when a chemical reaction makes two different atoms into a new product, the mass will be the same. Knowing this the mass of the copper should be the same at the beginning and at the end of the experiment.
In this investigation we will see some chemical changes such as formation of gas, temperature changes, solid formed, color change occurs or a new odor produced and physical changes such as freezing, melting, dissolving evaporating. Copper is a widely used metal, it is use in door handles, cooking pots, cars, swimming pool and hot tubes to control the yeast. Physical and chemical properties of copper: Symbol : Cu • Atomic number: 29 • Highly electrical and thermal conductivity • State at room temperature : Solid • Brownish red colour • Melting point : 1083 C • Density : 8. 93 g cm2 • Boiling point : 2595 C Copper is find in ores, an ore is a type of rock that contains minerals with important elements including metals, there is a lot of different copper ores such as Chalcopyrite, Covellite, Malachite, Azurite: Mineral |Formula |Appearance |% copper in | | | | |mineral | |Bornite |Cu5FeS4 |Golden brown, metallic |63 | |Malachite |CuCO3Cu(OH)4 |Bright green, earthy |58 | |Azurite |2CuCO3Cu(OH)4 |Blue, glassy |55 | |Chalcopyrite |CuFeS2 |Golden yellow, metallic |35 | Copper has bad toxic effects on plants, stunted root growth and leaf chlorosis are the two min symptoms, that’s why it is used as a fungicide. For humans, copper is part of the blood system, but a copper imbalance could be dangerous, and not very enjoyable. Firstly the nervous system dysfunctions, which could mean bipolar, depression, violence, fear… You could also get fungal and yeast infections much more easily. It also affects your reproductive system, infertility, miscarriage… A copper imbalance could also give you headaches, fatigue, insomnia, skin rashes… EXPERIMENTATION: • Stage 1:
Firstly weight the vial of copper given which was 11. 5 g, then weight the empty vial which was 9. 9 g. To know the mass of copper subtract those two numbers: 11. 5 – 9. 9 = 1. 6. The mass of copper is 1. 6g. it is solid, brown-orange colour, shinny, small and its shape is abnormal. The nitric acid is a transparent liquid, it looks like water. When pouring 15ml of the acid solution in the beaker the copper turns white then turquoise, it starts dissolving, bubbles are escaping from the copper, fuzzy looking brown toxic fumes is formed, it has a very strong odour. Add more acid if the copper isn’t fully dissolved, when it is the liquid is blue and there is no more copper.
A chemical reaction was formed since the liquid changed colour and there was a formation of a gas with a strong odour appeared. The copper didn’t disappear but it lost electrons and went into the solution. • Stage 2: The solution of sodium hydroxide is a transparent liquid, when slowly adding 40mL of this solution to the blue solution we obtained in the stage 1 the solution looks cloudy, heats up, smoke is coming out of the beaker and the solution is boiling. At the end of the reaction the blue colour turned lighter. A chemical reaction occurred once again because the temperature changed and the colour too. The copper is now still ions and it is in the solution. • Stage 3:
In stage three firstly add 100mL of distilled water to the light blue solution obtained in stage 2, heat it up and stir constantly till the solution boils. The solution changed colour, it went dark and a brown solid formed, A chemical reaction occurred since the solution changed colour, going from light blue to dark, a solid is also formed. After heating the solution let it cool for 5 minutes, then pour off the liquid trying to keep the solid, rinse the solid in distilled water. The copper turned into a solid. • Stage 4: Left with the brown solid formed in the earlier stage add 50 ml of the sulphuric acid given (H2SO4) which is a very corrosive, transparent liquid with no specific odour. The colour changed to teal and the solid dissolved, leaving a teal coloured solution.
Once again a chemical reaction occurred, a substance disappeared and the liquid changed colour. The copper is in the solution, the teal colour looks like the originl colour of the copper at the beginning of the experiment • Stage 5 Starting with the teal colour solution, add 5g of zinc (a brown solid metal) in the beaker and put a watch glass on top. The liquid formed bubbles, and a chlorine gas was produced. The solution turned clear and solid formed. The liquid is then removed to be replaced with water. The colour change, the formation of the gas and a solid proves that a chemical reaction occurred. • Stage 6: Left with the solid in the clear solution, wash the solid 3 times, and then weight a clean evaporating dish.
Pour as much of the solid you can into this dish, place the dish over a steam bath to get rid of the extra liquid. By the end only a brown solid remain, it’s mass is 1,6g. No chemical reaction occurred in stage 6. The mass of the solid found is the same than the mass of the copper at the start of the experiment; my hypothesis is that the solid found is copper. DISCUSSION: -In stage 1 the copper dissolved completely and the solution went blue, a toxic gas was also formed. Cu(s) + 4HNO3(aq) ( Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l) -In stage 2 the blue colour turned lighter and the solution heated up. Cu(NO3)2(aq) + 2NaOH(aq) ( Cu(OH)2(s) + 2NaNO3(aq) In stage 3 the colour of the solution changed once again, it went from light blue to dark blue, a solid was formed. Cu(OH)2(s) J( CuO(s) + H2O(g) -In stage 4 a substance disappeared and the solution turned into a teal colour. CuO(s) + H2SO4(aq) ( CuSO4(aq) + H2O(l) -In stage 5 the liquid went clear, a new solid formed and a chlorine gas formed. Cu+2(aq) + Zn(s) ( Cu(s) + Zn+2(aq) After going through that many chemical changes the copper remains the same. The copper found in stage 6 is small, shiny, it has a brown-orange colour, it’s mass is 1. 6g. It looks and weights exactly like the copper at the beginning of the experiment. It proves that the law of conservation of matter is true.
The results might not be totally appropriate since more substance was sometimes added to the solution, like in stage 1 where more nitric acid was added since the copper didn’t want to dissolve completely. This was a tricky experiment, not all of them worked. Most of the time the mass of the copper at the beginning and at the end isn’t the same because some could have been lost when pouring off the liquid in stage 3. It was also a dangerous experiment since a few corrosive acid were utilised, glasses had to be worn at all time and be really careful when pouring liquids in, firstly not to hurt yourself and to have the results the more appropriate than possible.
