substance ‘X’ is used for white washing. (i) Name the substance ‘X’ and write its formula. (ii) Write the reaction of the substance ‘X’ named in (i) above with water. Answer (i) The substance ‘X’ is calcium oxide. Its chemical formula is CaO. (ii) Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime). Question 2: Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas. Answer Water (H2O) contains
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fairly quickly‚ although some carbon stays in the plant till it dies and is decomposed. If the plant dies‚ the carbon can stay in the soil for millions of years; this is because the carbon is formed in very complicated chemical formulas that resist decomposition. If the plant‚ eg a tree‚ is made into a by-product such as paper‚ or a table‚carbon will remain in the wood
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acid with metal can be tested by bringing a lighted candle near it. If the gas burns with pop sound‚ then it confirms the evolution of hydrogen gas. Burning with pop sound is the characteristic test for hydrogen gas. Reaction of acids with metal carbonate: Acids give carbon dioxide gas and respective salts along with
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ST ANDREW’S JUNIOR COLLEGE JC 2 Preliminary Examination CHEMISTRY 9647/03 Higher 2 13 September 2010 Paper 3 Free Response 2 hours Candidates answer on separate paper. Additional Materials: Answer paper‚ Graph Paper‚ Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and civics group on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams‚ graphs or rough working. Do not use staples‚
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these kinds of water for a long time‚ calcium hydroxide in the cement paste dissolves first (per liter water can dissolve calcium hydroxide of 1.3g). Under the role of still water or zero-pressure water‚ the dissolution will stop because the surrounding water is easy to get saturated due to the dissolved calcium hydroxide‚ and dissolution only occur on the surface‚ little impact. But if the cement paste is in fluid water or pressure water‚ the dissolved calcium hydroxide is easy to be washed away‚
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Chemistry 1 Revision Booklet Unit Chemistry 1 Syllabus At the beginning of each sub-section‚ activities are stated which develop candidates. skills‚ knowledge and understanding of how science works. Details are then given of the substantive contexts in which these skills‚ knowledge and understanding should be set. It is expected that‚ where appropriate‚ teachers will adopt a practical approach‚ enabling candidates to develop skills in addition to procedural knowledge and understanding. Note that
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is really gypsum (calcium sulfate)‚ but often people call it "chalk". People use it for drawing on hard things‚ because it is soft. If this chalk is rubbed on something hard or rough‚ it will leave a mark. People often write with chalk on a chalkboard or blackboard. A chalk eraser or water can be used to clean the chalk marks away so the board is blankagain. Shops usually sell blackboard chalk in sticks that are about 5 cm long. The main component of chalk is calcium carbonate (CaCO 3 )‚ a form
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chemical reactions- combustion (often called burning)‚ synthesis‚ decomposition‚ neutralization‚ single replacement and double replacement. A combustion reaction is a reaction with oxygen‚ and heat is evolved (given off). A common example of combustion is Hydrogen +Oxygen= Water Synthesis is a reaction where two or more substances combine to make a compound. An example of a synthesis reaction is Iron + Oxygen = Iron Oxide Decomposition is the opposite of synthesis. It is the breakdown of a compound
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Determine the Enthalpy Change of a Reaction Background Calcium Carbonate‚ CaCO₃‚ decomposes with heat to form CaO and CO₂. The objective of this practical was to determine the enthalpy change for this reaction by using an indirect method based upon the foundation of Hess’ Law. Both calcium oxide and calcium carbonate react readily with 2 mol/dm3. The reaction can be demonstrated as so: CaCO₃ (s) -> CaO(s) + CO₂ (g) Results: Raw Data Calcium Carbonate Mass of CaCO₃ + Weighing Bottle (in grams) 3.62g±0
Free Thermodynamics Enthalpy Calcium carbonate
HCl sodium nitrate potassium chloride. magnesium sulfate calcium nitrate sodium carbonate. Safety notes: 1. Wear aprons and goggles. Protective gloves are also available. 2.Carefully read the labels of all chemicals before use. Abide by specific warnings and directions. 3. Collect all materials needed
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