Presentation on theme: "Acids and Alkalis Name_____________________. Universal Indicator and the pH scale Below 7 is _____ Above 7 is _________ Exactly 7 is _________ Universal."— Presentation transcript:
Universal Indicator and the pH scale Below 7 is _____ Above 7 is _________ Exactly 7 is _________ Universal Indicator changes colour depending on whether it is in an acid, alkali or neutral solution. Stomach acidLemon juiceWaterSoapOven cleanerBaking powder
Quiz on acids and alkalis 1)This has pH of less than 7 ____________ 2)This is often used in cleaners or soap __________ 3)This would turn Universal Indicator red ________ 4)Sodium hydroxide is an ____________ 5)This would feel soapy on your skin _________ 6)This could burn your skin _________ 7)This will turn universal indicator purple _________ 8)Lemon juice and vinegar are examples of weak _______ 9)limewater (calcium hydroxide) is an example of this__________ Acid, alkali or both???
Answers acid alkali acid alkali both alkali acid alkali
E.g. hydrochloric acid + sodium hydroxidesodium chloride + waterNeutralisation An acid and alkali will cancel each other out (neutralise) each other if the correct amounts are used Acid + alkaliSalt + water This reaction is called ________________ because the acid is used up and _________ is made. Choose your answers from the list below: combustionrespirationneutralisation hydrogenwateroxygen
Names of salts The name of a salt depends on the acid and the alkali that are used to make it. The first part of the name of the salt comes from the alkali. Sodium hydroxide reacts with acids to make salts that start with sodium. The second part of the name of the salt comes from the acid. Hydrochloric acid makes salts that end with chloride.
Naming salts 2 Hydrochloric acid makes salts that end with chloride. Sulphuric acid makes salts that end with sulphate. Nitric acid makes salts that end with nitrate. Adding sodium hydroxide to nitric acid will make water and a salt called sodium nitrate. sodium hydroxide + nitric acid water + sodium nitrate.
Adding potassium hydroxide to sulphuric acid will make water and a salt called _________ _________. Complete the blanks spaces Adding sodium hydroxide to hydrochloric acid will make water and a salt called sodium _________. Adding sodium hydroxide to nitric acid will make water and a salt called sodium _________. Adding magnesium hydroxide to hydrochloric acid will make water and a salt called _________ _________. Adding lithium hydroxide to sulphuric acid will make water and a salt called _________ _________.
Adding acid to carbonates Carbonates are compounds containing carbon and oxygen. When an acid and a carbonate are added together, the mixture starts to fizz. A gas called _________ _________ is produced. The limewater will go __________
What else is made???? You know that carbon dioxide is made when an acid reacts with a carbonate. Two other new substances are made as well. A salt is made and so is water. metal carbonate + acid carbon dioxide + salt + water This reaction is called ________________ because the acid is used up and _________ is made. The name of a salt depends on the acid and the carbonate. Adding calcium carbonate to hydrochloric acid will make a salt called calcium chloride. calcium + hydrochloric carbon + calcium + water carbonate acid dioxide chloride
Adding potassium carbonate to sulphuric acid will make carbon dioxide, water and a salt called ___________ _________. Complete the blanks spaces 2 Adding sodium carbonate to hydrochloric acid will make carbon dioxide, water and a salt called _________ _________. Adding sodium carbonate to nitric acid will make carbon dioxide, water and a salt called __________ _________. Adding magnesium carbonate to hydrochloric acid will make carbon dioxide, water and a salt called ___________ _________. Adding copper carbonate to sulphuric acid will make carbon dioxide, water and a salt called _________ _________.
Uses of acid reactions When acids react new chemicals called salts are made. These salts have many uses. Sodium chloride is the chemical name for table salt that we put on our chips. Salts that are made from nitric acid contain nitrate. Nitrates are needed by plants to help them grow. Chemical companies use nitric acid to make nitrate salts for farmers to use as fertilisers for their crops. Nitrate salts are also used in explosives.
Useful acid-alkali reactions 1) Hydrochloric acid is used in the stomach to help digest food. If we eat too many “rich” foods our stomachs make too much ______. This is called _____________. Indigestion tablets take away this pain because they ______________ the acid. 2) Soil is often acidic, mainly due to acid ____. This can have bad effects on ______ and vegetable growth. ________ is an alkali that farmers and gardners add to soil to _________ the acid. Words – plant, indigestion, neutralise, rain, acid, neutralise, lime
Reactions of metals with acids When a metal reacts with an acid a gas called ______________ is made. A salt is also made at the same time. METAL + ACID SALT + ____________ e.g. magnesium + hydrochloric acid magnesium chloride + hydrogen The name of the salt depends on the metal and the acid. Complete the following reactions: Calcium + hydrochloric acid _________ ________ + __________ Zinc + hydrochloric acid _________ ________ + __________ Iron + nitric acid _________ ________ + __________ Lithium + sulphuric acid _________ ________ + __________ These reactions are not neutralisation because _________ is not being made.
Testing for hydrogen “POP” Testing for hydrogen: Hydrogen will make a _______ splint go _______
If a salt is present we will see it when we evaporate the water. Testing for salts
Acid gases The names of three acid gases are: _________ _________ When fossil fuels like coal, _____ or natural _____ are burned in power stations, the carbon contained in them reacts with oxygen to form ___________ dioxide gas. Carbon dioxide also comes out of car exhausts. Some fossil fuels contain sulphur. When the fuel burns, the acid gas called _________dioxide is made. A car engine needs a spark to set the petrol on fire. The energy from the spark makes nitrogen and oxygen join together to make the acid gas called__________ dioxide gas.
Problems with acid gases The acid gases called _________ dioxide, _________ dioxide and _______ dioxide dissolve in cloud droplets and fall as _____ ______. The acid rain gets into rivers and streams and kills ______. It can kill ______ when it falls onto their leaves. Acid rain can also damage stone buildings and metal structures because it reacts and eats them away.