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Chemistry My family and home 03/07/2015
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Acids and bases (alkalis) Used by the body, used in other processes: such as food, farming and chemical industries. 03/07/2015
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Chemistry Lesson Safety in chemistry Acids and alkalis (bases) Neutralisation Using indicators Practical work 03/07/2015
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Hazard signs to learn… hi flammable HarmfulIrritant Corrosive
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03/07/2015 Hazard signs to learn… Radioactive Oxidising Dangerous for environment Toxic
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Safety Irritant- can cause a rash or itching Harmful-general damage to living organisms Corrosive-will burn through materials 03/07/2015
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Safety instructions Wear goggles Follow safety instructions 03/07/2015
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Acids and bases Acid- A substance that produces hydrogen ions (H + ) when it dissolves in water. Bases- Compounds which react with acids to neutralise them Alkali- A soluble base, forms hydroxide OH - ions in water. Neutral-not an acid or base 03/07/2015
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Symbols in word equations -states of matter (l) liquid (g) gas (s) solid (aq) aqueous-dissolved in water 03/07/2015
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Acids and bases (alkalis) 03/07/2015
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Acid Examples of acids include : Vinegar, orange or lemon juice, acid rain, stomach acid, nitric acid, sulfuric acid, hydrochloric acids Used in car batteries, food and drinks, preserving food, in body. 03/07/2015
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Acid Hydrochloric acid is formed when hydrogen chloride is gas dissolves in water. HCl (g) H + (aq) + Cl - (aq) 03/07/2015
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Alkali (bases) Examples and uses include: metal hydroxides, metal oxides, cleaning products, stomach antacids, baking powder. 03/07/2015
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Alkali Sodium hydroxide is formed when the solid is dissolved in water. NaOH (s) Na + (aq) + OH - (aq) 03/07/2015
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What is an acid? Is an alkali (OH or H) Give a use of an acid 03/07/2015
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1.An Indicator is a dye that changes colour 2.Indicators can be used to find out whether a solution is acid, alkaline or neutral 3.Universal Indicator can be used to find the pH of a solution Acid – red, pH less than 7 Neutral – green, pH = 7 Alkali – blue, pH greater than 7 pH scale
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03/07/2015 Universal Indicator and the pH scale Strong acid Strong alkali Neutral Universal Indicator is a mixture of liquids that will produce a range of colours to show how strong the acid or alkali is: 0-14 Stomach acidLemon juiceWaterSoapOven cleanerBaking powder 0
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pH scale
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Practical 1 Test chemicals to find pH Use paper and liquid Record results in a table 03/07/2015
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1.Acids react with alkaline solutions to form a salt and water Hydrochloric acid produces chlorides Nitric acid produces nitrates Sulphuric acid produces sulphates 2.Ammonia can dissolve in water to produce an alkaline solution. This can be neutralised with acids to produce ammonium salts 3.Indicators can monitor neutralisation reactions Neutralisation Neutralisation
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03/07/2015Neutralisation An acid and alkali will neutralise each other (if the correct amounts are used): Acid + alkaliSalt + water Acid + base Salt + water E.g. hydrochloric acid + sodium hydroxidesodium chloride + water
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Neutralisation Acids and bases neutralise each other. Acids form H + (aq) ions in water Alkalis form OH - (aq) ions in water Acid + alkali salt + water H + + OH - H 2 O The other parts form the salt. 03/07/2015
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Neutralisation – Hydrochloric acid Neutralisation
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Neutralisation – Sulphuric acid Neutralisation
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Neutralisation – Nitric acid Neutralisation
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Questions Write a word equation for adding hydrochloric acid to magnesium hydroxide Extension : Write a balanced symbol equation for this reaction (difficult) Hint Mg(OH) 2 MgCl 2 03/07/2015
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Answers Acid + base salt + water Hydrochloric acid + Magnesium hydroxide magnesium chloride and water 2HCl + Mg(OH) 2 MgCl 2 +2H 2 O 03/07/2015
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Neutralisation – Fertiliser Neutralisation
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Practical 2 Titrations and neutralisation 03/07/2015
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Useful acid-alkali reactions 1) Hydrochloric acid is used in the stomach to help _______. If we eat too many “rich” foods our stomachs create too much ____ – this is called ______. This acid needs to be neutralised by taking indigestion tablets. 2) Soil is naturally acidic, mainly due to acid ____. This can have bad effects on ____ and vegetable growth, so the excess acid may need to be neutralised with an _____. Words – plant, digestion, indigestion, alkali, rain, acid
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03/07/2015 Quiz on acids and alkalis 1)This a pH of less than 7 2)This would turn Universal indicator green 3)This is often used in cleaners or soap 4)This would turn Universal Indicator red 5)Sodium hydroxide is a common ____________ 6)This would feel soapy on your skin 7)This could be a corrosive 8)This will turn universal indicator purple 9)This would taste sour 10)Lemon juice and vinegar are examples of weak _____ Acid, alkali or both???
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Acids and metals Acid + metal Salt + hydrogen 03/07/2015
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Metals and acids The more reactive the metal, the faster the reaction The speed of reaction is indicated by the rate at which bubbles of hydrogen are produced. Test for hydrogen???? Name of salt depends on metal and acid used 03/07/2015
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Reaction of Metals and Acid
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Hydrochloric acid Produces Chloride salts Magnesium + Hydrochloric acid Magnesium Chloride + ________ _______ + Aluminium +Aluminium Chloride + __________ ________+ ________ Zinc chloride + _________ 03/07/2015
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Hydrochloric acid Produces Chloride salts Magnesium + Hydrochloric acid Magnesium Chloride + hydrogen Hydrochloric acid + Aluminium +Aluminium Chloride + hydrogen Hydrochloric acid+ zinc Zinc chloride + hydrogen 03/07/2015
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Symbol equations 2HCl + Mg MgCl 2 +H 2 ____HCl + 2Al 2AlCl 3 + 3H 2 2____ + ____ ZnCl 2 + H 2 03/07/2015
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Symbol equations 2HCl + Mg MgCl 2 +H 2 2HCl + 2Al 2AlCl 3 + 3H 2 2HCl + Zn ZnCl 2 + H 2 03/07/2015
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Sulfuric acid reactions H 2 SO 4 + ______ MgSO 4 + H 2 3H 2 SO 4 + 2Al Al 2 (SO 4 ) 3 + 3H 2 H 2 SO 4 +Zn ZnSO 4 + H 2 Copy and complete write a word equation for each. 03/07/2015
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Sulfuric acid reactions H 2 SO 4 + Mg MgSO 4 + H 2 3H 2 SO 4 + 2Al Al 2 (SO 4 ) 3 + 3H 2 H 2 SO 4 +Zn ZnSO 4 + H 2 Sulfuric acid + magnesium Magnesium sulfate + hydrogen 03/07/2015
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Nitric acid Nitric acid reacts with alkalis, but when reacting with metals it can produce nitrogen oxides. 03/07/2015
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1.Transition metal oxides and hydroxides do not dissolve in water. They are called bases 2.They react with acids to produce salts that are soluble 3.The excess metal oxide can be filtered off Metal Oxides & Hydroxides
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Metal hydroxide Metal hydroxide + acid salt + water 03/07/2015
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Metal oxide Metal oxide + acid salt + water 03/07/2015
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Adding acid to carbonates Carbonates are compounds containing carbon and oxygen. When an acid is added to a carbonate the carbonate starts to fizz. A gas called _________ _______ is produced. Calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water CaCO 3(s) + HCl (aq) CaCl 2(aq) + CO 2(g) + H 2 O (l) 2
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Metal carbonate Metal carbonate + acid water + salt + carbon dioxide 03/07/2015
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Quiz Quiz
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