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Profile Hi! I'm Clarence!I like sleeping and playing computer and stuff like that. I like playing soccer on the xbox and in real life, although i don't get that many chances to play. I love movies. Especially horror movies or comedy. |
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Profile Hi! I'm Clarence!I like sleeping and playing computer and stuff like that. I like playing soccer on the xbox and in real life, although i don't get that many chances to play. I love movies. Especially horror movies or comedy. |
Music |
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Thursday 22 September 2011
Ionic Equations, Colours of Cations & Anions, Acids, Bases, Alkalis, Salts Q1 Zinc nitrate reacts with aqueous ammonia (NH4OH) to form a salt and a base. (i) Name the salt and the base. The salt is zinc nitrate, and the base is zinc hydroxide. (ii) Describe the observations for the reaction. white precipitation is formed, soluble in excess giving a colourless solution. (iii) Write a chemical equation for the reaction (include state symbols). Zn(NO3)2 (aq) + 2NH4OH (aq) --> Zn(OH)2 (s) + 2NH4NO3 (aq) (iv) Write an ionic equation for the reaction. Zn2+ (aq) + 2OH- (aq) --> Zn(OH)2 (s) Q2 Ammonium sulfate is heated with sodium hydroxide. (i) Write a chemical equation (include state symbols) for the reaction. (NH4)2SO4 (aq) + 2NaOH (aq) --> 2NH3 (g) + Na2SO4 (aq) + 2H2O (L) (ii) Describe a test for the gas. It turns damp red litmus paper blue. Q3 An unknown green solution is heated with a piece of aluminium foil and sodium hydroxide solution. (i) The gas produced turns damp red litmus paper blue. Name the gas evolved. Ammonia (ii) This is a confirmatory test for an anion. Name this anion. Nitrate (NO3-) in solution (iii) Give a possible cation which gives the green solution. iron(III) Q4 Sulfuric acid is titrated with potassium hydroxide in the preparation of potassium sulfate salt. (i) Explain why this method is recommended for the preparation for this salt. Potassium hydroxide and sulfuric acid and potassium sulfate salt are all soluble and colourless solutions so titration is the best method. (ii) Write an ionic equation for the reaction. H+ (aq) + OH- (aq) --> + H2O (L) Q5 Excess zinc carbonate is added to hydrochloric acid in the preparation of zinc chloride salt. (i) Write an ionic equation for the reaction. (CO3) 2- (aq) + 2H+ (aq) --> H2O (L) + CO2 (g) (ii) Why excess zinc carbonate is used? Excess is used to ensure that it has completelty reacted with the hydrocloric acid. (iii) Briefly explain how the zinc chloride crystals can be obtained. Add excess zinc carbonate to a beaker of hydrochloric acid until there is excess zinc chloride left behind. Filter to remove the excess unreacted zinc carbonate solid. Then evaporate the zinc chloridesolution to remove the water and make a saturated solution. The hot saturated solution would form zinc chloride crystals when cooled. 06:12
Friday 8 July 2011
Me and my family!!!!    07:04
Jia le (36) Blog is simple and nice. Answers are expained clearly. Pictures show and explain the answers more clearly. Atom structures are draw very well. Answers are in different colours which makes it easier to see. Helmi (35) Blog is very creative and nice. The explanation of the answer to question five is very good and as it was explained very well. The drawing of electrons are also done very well, being very accurate. Grace (04) Blog is very simple and nice. But the wording is too small. Her answer for question 5 is very well written and creative, especially the part about the non-metals. The answers are easy to understand. 06:47
Sunday 3 July 2011
Chemistry 1. What does an atom looks like? What are the sub-atomic particles inside it.....(talk about electrons, neutrons, protons, electron shells, nucleus....) An atom consist of 3 different particles- protons, neutrons and electrons. These are smaller then the atoms. they are called sub-atomic particles.Protons are positive (+1 charge) with a relative mass of 1, neutrons are neutral,which means that it has no electric charges. It also has a relative mass of 1 while electrons are negative (-1 charge) with a relative mass of roughly 1/1840. 2. Draw the atomic structure of a sodium atom and a sodium ion....explain why you draw it this way.  For the sodium atom which has electronic structure of (2.8.1) it has to lose 1 electron to become stable..By losing 1 electron,it becomes a sodium ion with an electronic structure of (2.8). Picture from Chun Boon of 3E5 3. Draw the atomic structure of a sulfur atom and a sulfide ion....explain why you draw it this way.  For the sulfur atom which has electronic structure of (2.8.6) it has to gains 2 electron to become stable..By gaining 2 electrons,it becomes a sulfide ion with an electronic structure of (2.8.8). Picture taken form Wendy of 3E5 4. Chlorine-35 atom and Chlorine-37 atom are called isotopes...Use these two examples to explain what is 'isotopes'. Isotopes are atoms of the same element with the same number of protons but differents number of neutrons. Chlorine-35 has 35 as its nucleon number. So it has 17 protons with 18 neutrons. Chlorine-37 has 37 as its nucleon number. So it has 17 protons with 20 neutrons. So they are isotopes as they have the same proton number but different nucleon numbers. 5. Sodium is a metal and sulfur is a non-metal....why we classify them this way? Metals are from group I, II, III and from transition metals which are between group I and group II. Non-metals are from group IV, V ,VI and group 0 Sodium is from group I, it will achieve the electronic structure of the noble gas if they lose one electron, in which it would become a sodium ion. Sulfur is from group VI, it will achieve the electronic structure of the noble gas if it gains two electron, so it would become a sulfur ion. 22:31
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Affiliates Aaron Agnes Aleen CekMin Charmaine Chelsea Chun Boon Cindy Clarence EiEi Fabian Grace Helmi HweeLeng Janis JiaLe JieEn JunJie JunWei KaiQi Michelle MingSiew Nicole Rupini ShinYoong ShuYu SiukGeok Su WanLing Wendy XinHui XinKang XueLi XueTing Yihui YiJin YiTing Ysabelle Zane ZeWei Ziqing |