Best Results From Yahoo Answers

From Yahoo Answers

Question:I looked around the internet and it says that when a metal reacts with an acid, a salt and hydrogen is produced. But we did an experiment where we put a piece of metal e.g. zinc, copper, aluminum, magnesium, into hydrochloric acid, only the magnesium produced a pop sound? Please explain :)

Answers:For a metal to react with an acid to form a salt and hydrogen gas, it has to be above hydrogen in the electrochemical series (ECS). The Electrochemical Series is a list of elements in order of their reactivity (high to low). The list is as follows: Potassium(most reactive), Sodium, Calcium, Magnesium, Aluminium, Zinc, Carbon, Iron, Tin, Hydrogen, Lead, Copper, Silver, gold(least reactive) In your experiment, the Magnesium reacted most vigorously hence producing a lot of Hydrogen gas, which when lit with a glowing splint burned with a pop. Mg + 2HCl ------------------->MgCl2 + H2 Zinc should also have produced hydrogen gas quickly, however not as quickly or vigorously as Magnesium. Maybe a smaller amount of zinc was used in the experiment - hence the proportion of Hydrogen gas produced would be less. Zn + 2HCl --------------------> ZnCl2 + H2 Aluminium should also produce hydrogen gas when reacted with HCl acid, however the aluminium may have been coated in Aluminium Oxide (due to corrosion with oxygen in the air). This coating has to be dissolved by the Hydrochloric Acid before the main reaction proceeds. So the reaction takes longer to start but when it does it will produce Hydrogen gas. To dissolve the Al2O3 (aluminium oxide coating the aluminium metal) Al2O3 + 6HCl---------------------------> 2AlCl3 + 3H2O The main reaction then is: 2Al + 6HCl -----------------------> 2AlCl3 + 3H2 Finally Copper will not react with Hydrochloric Acid to produce Hydrogen gas as it is below Hydrogen in the Electrochemical Series.

Question:here is the procedure that our teacher gave us. pls help me because the materials are not enough as well as the chemicals.. PROCEDURE 1.PREPARATION OF HYDROGEN CAUTION: No flame should be near the hydrogen generator. a.Place 10 grams of granulated zinc into the flask and stopper tightly. b.Pour enough water through the thistle tube to cover the zinc. Add 6-10 drops copper sulfate solution. c.Prepare 9N Sulfuric acid by pouring slowly 15 mL of concentrated acid into the beaker containing 45 mL of water. (NOTE: Always add acid into water.) d.Stir the water with a glass rod while adding the acid. Cool the dilute acid and pour about 5-mL portions of it through the thistle tube. Excess acid causes vigorous reaction. e.Discard the first test tube of gases that come out of the delivery tube. Collect 5 test tubes of pure hydrogen gas by water displacement and stopper tightly. Write the equation for the reaction between zinc and copper sulfate. ______________________________________________________________________________ Write the equation for the reaction between zinc and sulfuric acid. ______________________________________________________________________________ Should the test tubes of hydrogen be set upward or downward? Why? ______________________________________________________________________________ What type of catalyst is copper sulfate? ______________________________________________ 2.PROPERTIES OF HYDROGEN a.Based on your observation during its preparation, determine the following properties of oxygen: Color: ________________________ Odor: ________________________ Taste: ________________________ Solubility in water: _______________ b.Allow one test tube of hydrogen to stand for 15 seconds upward with its mouth uncovered and then place a lighted splinter over its mouth. Repeat the test process with another test tube of hydrogen leaving it open for 45 minutes. Observation: First test tube: _______________________________________________________________ Second test tube: ____________________________________________________________ What is the significance of the result of the second test tube? ___________________________________________________________________________ c.Place a test tube of hydrogen in an inverted position. Remove the stopper and immediately place an empty test tube below it, bringing the two containers mouth to mouth. Carefully reverse their position while still attached to each other and let it stand for 30 seconds. Test each test tube for the presence of hydrogen gas. Observation: ___________________________________________________________________________ d.Insert a lighted splinter into an inverted test tube of hydrogen. Slowly withdraw the splint and again thrust it into the gas. Repeat as long as the phenomenon continues. Equation for the combustion of hydrogen: ___________________________________________________________________________ What happened to the splinter: (a) when it is thrust into the gas? ___________________________________________________________________________ (b) when it is withdrawn? ___________________________________________________________________________ 3.REACTION OF METALS WITH ACIDS a.In 7 separate test tubes place 5 mL of 6N HCl. b.Test the reaction of the acid when a few pieces of the following metals are added to the different test tubes: granulated zinc, iron filings, copper filings, granulated aluminum, magnesium ribbon, granulated tin, and pulverized antimony. c.Observe the rate at which hydrogen is evolved in each tube. Equation for the reactions which occurred Order of reactivity

Answers:Laboratory procedures are designed to give you the first-hand experience with chemical reactions. By doing the lab you have the opportunity to observe what is happening, and you can then form your own conclusions. I could give you all the answers to the questions, and then you would not be compelled to do the procedure at all. That would be unfortunate, because you would not learn anything from it and you would miss an exciting experience. I'll just comment that in general, more reactive metals will react with dilute acids displacing hydrogen gas, and forming salts of those metals. Less reactive metals will not react with dilute acids. For metallic reactivity series, consult a reference table (see the links below). Hydrogen gas has the lightest molecules of all the known gases, so its density is much less than that of air.

Question:Please, please. I REALLY, REALLY need your help. Here is the question: Three metal nitrates are named P,Q and R. On heating: P melts and effervesces. The gas given off relights a glowing splint. Q goes from white to yello an dreleases brown fumes. R goes blue to black and releases brown fumes. a) Which nitrate contains a transition metal? Explain your answer. b) Which nitrate probably contains a Group 1 metal? Explain your answer and write a word equation for the reaction. c) What are the brown fumes produced by Q and R.. What test would you carry out to identify them? d) Suggest the identity of R. Please, please I will be REALLY grateful if you could answer these. I need your help. Thanks

Answers:(a) R contains a transition metal - amongst the nitrates, only transition metal nitrates are coloured; others are white. (b) P. The gas that relights a glowing splint is oxygen, and producing oxygen without any coloured gas suggests the thermal decomposition of a group I nitrate, via: group I nitrate ---heat---> group I nitrite + oxygen gas 2 NaNO3(l) ---heat---> 2 NaNO2(l) + O2(g) is an example. Withe further heating, the nitrite will also decompose to form nitrogen and oxygen and the metal oxide, such as: 4 NaNO2 ---heat---> 2 Na2O + 2 N2 + 3 O2 (c) The gas is nitrogen dioxide, NO2, which has a characteristic brown colour and pungent odour. It is commonly observed in the thermal decompostion of some nitrates. For example: 2 Pb(NO3)2(s) ---heat---> 2 PbO(s) + 4 NO2(g) + O2(g) Other than by its colour and odour, the presence of nitrogen dioxide can be confirmed by using potassium iodide - starch paper. NO2 reacts with the iodide to produce iodine, which stains the starch on the paper blue-black. (d) R is likely copper(II) nitrate. Blue is a characteristic colour for copper(II) compounds, and the thermal decomposition would be predicted to produce cupper(II) oxide, which is a black solid: 2 Cu(NO3)2(s) ---heat---> 2 CuO(s) + 4 NO2(g) + O2(g) Cu(NO3)2(s) = blue CuO(s) = black

From Youtube

Elephant Toothpaste

Dish soap is placed in large flask with 20 mL of 30% hydrogen peroxide. Two different colours of food colouring are dribbled down the neck of the flask. Add 5 g KI (POTASSIUM IODIDE) powder and step back. (30% hydrogen peroxide and potassium iodide cannot be bought in local stores - google to find out where to buy) The exothermic reaction produces heat and oxygen gas and a lot of foam. Plunge a glowing splint into the foam. The pure oxygen will cause it to relight until it gets too wet. This activity is excellent for discussions about catalysts, exothermic reactions and decomposition reactions. 2H2O2 = 2H20 + O2.

Warning: mysql_close(): supplied argument is not a valid MySQL-Link resource in /edu-source/cbsenext/cfw/index.php on line 550