CHEMICAL REACTION (SYNTHESIS REACTION, DECOMPOSITION AND SINGLE REAPLACEMENT REACTION) Purpose: 1. To identify the chemical changes 2. To observe the effect of temperature of a chemical reaction. Theoritical basic : A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that strictly involve the motion of electrons in the forming and breaking of chemical bonds between atoms, and can often be described by a chemical equation.
The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which graphically present the starting materials, end products, and sometimes intermediate products and reaction conditions.
Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration, and rapid reactions are often described as spontaneous, requiring no input of extra energy other than thermal energy. Non-spontaneous reactions run so slowly that they are considered to require the input of some type of additional energy (such as extra heat, light or electricity) in order to proceed to completion (chemical equilibrium) at human time scales. Different chemical reactions are used in combinations during in chemical synthesis in order to obtain a desired product.
In biochemistry, a similar series of chemical reactions form metabolic pathways. These reactions are often catalyzed by protein enzymes. These enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions may be performed at the temperatures and concentrations present within a cell. The general concept of a chemical reaction has been extended to non-chemical reactions between entities smaller than atoms, including nuclear reactions, radioactive decays, and reactions between elementary particles as described by quantum field theory. Reaction types.
There are three basic types and representation of three basic chemical reactions types: synthesis, decomposition and single replacement SYNTHESIS In a synthesis reaction, two or more simple substances combine to form a more complex substance. These reactions are in the general form: A + B > AB Two or more reactants yielding one product is another way to identify a synthesis reaction. One example of a synthesis reaction is the combination of iron and sulfur to form iron(II) sulfide: 8Fe + S8 > 8FeS Another example is simple hydrogen gas combined with simple oxygen gas to produce a more complex substance, such as water.
DECOMPOSITION A decomposition reaction is the opposite of a synthesis reaction, where a more complex substance breaks down into its more simple parts. These reactions are in the general form: AB > A + B One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas: 2H2O > 2H2 + O2 SINGLE REPLACEMENT In a single replacement reaction, a single uncombined element replaces another in a compound; in order words, one element trades places with another element in a compound These reactions come in the general form of: A + BC > AC + B
One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas: Mg + 2H2O > Mg(OH)2 + H2 Material and Equipment : 1. Sandpaper1 pc 2. Cu wire (Cooper)1 pc 3. Mg wire (Magnesium)1 pc 4. Bunsen burner1 pc 5. Spatula1 pc 6. CuCO31 spoon of Spatula 7. Test tube2 pc 8. Glass tube1 pc 9. Rubber stopper1 pc 10. Ca(OH)25 ml 11. CuCl2 1M5 ml 12. Iron nail1 pc 13. Iron powder 1 spoon of Spatula PROCEDURE Practical Procedures of Types of chemical Reaction| A. Synthesis reaction 1. Use fine sandpaper to clean piece of copper and magnesium wire until the wire is shiny. . Burn the wire of copper and magnesium in a burner flame for 1-2 minutes. 3. Note the appearance| | B. Decomposition Reaction 1. Obtain two spatula full of CuCO3, place them in a large test tube 2. Insert the glass tube into a one-hole rubber stopper connect it to the large test tube 3. Pour about 5mL of Ca(OH)2 solution into a small test tube 4. Place the end of the right angle glass tube in the small test tube containing Ca(OH)2 solution 5. Heat the tube containing CuCO3. 6. Note the appearance| | C. Single Replacement Reaction 1. Add about 5mL of 1M CuCl2 solution into a clean test tube 2.
Place iron nail into the solution 3. Take out the nail and observe the changes 4. Add a little iron powder into the solution and record the changes| | OBSERVATION I. Synthesis Reaction Indicator| Observation| | Magnesium| Cooper| Changes that occur for cooper and magnesium (before experiment)| The colour dark gey because of oxidation, then clean up first, until it shine enough | The colour dark red because of oxidation, then clean up first, until it shine enough| Changes that occur for cooper and magnesium (during experiment=being heated)| The colour become white, the fire occur green olour| The colour become dark grey, make a curve| Changes that occur for cooper and magnesium (after experiment)| Fragile when it touch , the magnesium become powder| Different colour| Reaction: 2 Mg(s) + O2(g) —–> 2 MgO(s) Cu + O2 –> CuO II. Decomposition Indicator| Observation| | Ca(OH)2| CuCO3| Changes that occur for Ca(OH)2and CuCO3(before experiment)| Colourless| Colourless| Changes that occur for Ca(OH)2and CuCO3 (during experiment)| Occur some buble| Heated| Changes that occur for Ca(OH)2and CuCO3 (after experiment)| The water move , not clear| Presence of precipitate| Reaction:
CuCO3 –> CuO + CO2 Ca(OH)2 + CO2 –> CaCO3 + H2O. III. Single replacement Reaction Indicator| Observation| | Iron nail into CuCl2| Iron powder into CuCl2| Changes that occur for iron nail and iron powder(before experiment)| Colour: rey| Colour: Grey| Changes that occur for iron nail and iron powder (during experiment)| Occur some buble| Sediment in above| Changes that occur for iron nail and iron powder( (after experiment)| Change colour| Change the colour of CuCl2| Reaction : Fe + CuCl2 = Cu + FeCl2 DISCUSSION From the experiment, we can learn about many kinds of chemical reaction. For the first experiment we can can see that metal will be oxidate and react with fire. With resulting is 2 Mg(s) + O2(g) —–> 2 MgO(s) Cu + O2 –> CuO By the change of form and colour we can conclude that there are chemical reaction happen. * For the second experiment , there is chemical reaction happen . Because the bubble is exist and also the solution change color from colorless become turbid with precipitate. Copper Carbonate (CuCO3) is heated up so that a decomposition reaction occurs, with the products being Copper (II) Oxide (CuO) and Carbon Dioxide (CO2).
The chemical formula is: CuCO3 –> CuO + CO2. If proper apparatus is set up, the carbon dioxide should travel down a tube into limewater (Ca(OH)2), which react to create solid calcium carbonate (CaCO3, also known as chalk) and water (H2O). The calcium carbonate is the reason why the ‘limewater’ turns milky. This proves that there is CO2 present. The chemical formula for this is: Ca(OH)2 + CO2 –> CaCO3 + H2O. * For the third experiment, there is chemical reaction too. Bacause the nail react with CuCl2. The nail experienced corotion. There is bubble production at the body of nail.
After we add the iron powder, there is color changing. So it prove the chemical reaction. A substitution or single displacement reaction is characterized by one element being displaced from a compound by another element. * In a chemical change, chemical reaction takes place and the substances undergo a change in their state. During chemical reactions, one substance reacts with another to form a new substance. The chemical composition of the new substance is different from that of the reacting species. Due to a chemical change, the chemical properties of matter also change.
That means the product is entirely different from either of the reactants. Some chemical reactions may be either exothermic or endothermic in nature. The error that might be effect in this experiment are : 1. The rushness when moving the tools. 2. We do not predict when the Bunsen burner is off what will happen 3. The mistake when we choose the equipment for decomposition experiment. 4. We do not train enough when we use bunsen burner 5. The time also we can not predict for how long the experiment will take place. CONCLUSION From the three experiments that we conducted, we can conclude that there are any changes. During chemical reactions, one substance reacts with another to form a new substance. The chemical composition of the new substance is different from that of the reacting species. Due to a chemical change, the chemical properties of matter also change. That means the product is entirely different from either of the reactants. For example : presence of bubbles, precipitation , and color changing. This of all include the chemical reaction properties. REFERENCES http://myclass. peelschools. org/sec/11/31552/Resources/TEXTBOOK/4-3. pdf http://wiki. answers. com/Q/Copper_carbonate_and_limewater