13. ACIDS, BASES AND SALTS 1. Work in pairs. Ask and answer questions. Practice different tenses: - present perfect simple: Have you ever seen a kangaroo? - present perfect continuous: How long/since when have you been studying languages? - past simple: When did you start learning English? Questions A: 1. How long ………………………… (you study) chemistry? 2. ……..you ever ……… (meet) the president of the Czech Republic? 3. What ……………………………… (you do) last week? 4. How many countries ………………………. (you visit)? 5. Since when …………………………………(you stay) in Brno ? 6. How long …………………….. (you know) your best friend? 7. Where …………………….(you go) on holiday last year? 8. How long ………………………. (you have) your mobile phone? Questions B: 1. How long …………………….. (you learn) English? 2. …………you ever…………… (be) to England? 3. When ……………………………….. (you finish) grammar school? 4. …………………you already ……………(read) Harry Potter ? 5. How long ………………………. (you live) in your town? 6. What ………………………….. (you do) yesterday? 7. …………you ever ……………. (eat) Japanese food? 8. How long ………………………. (you have) your computer? 2. What is the PH scale? What does it measure? 3. a) Put the strips of papers with food items along the scale, according to their PH factor from high alkaline, to alkaline, low alkaline, low acid, acid to high acid. What is important is their effect on the body– e.g. foods labelled as “highly acid” cause high acidity. b) What problems might consuming too many acidic foods cause? 4. Acids, bases and salts – definitions. Watch the video^1 Acids, bases and salts and complete the text below with missing pieces of information. The Swedish chemist Svante Arrhenius introduced the theory of ionization and used this theory to explain much about the behaviour of acids and bases. An Arrhenius acid is defined as any compound that _______________ in aqueous solution to form ______________ ions. HNO[3](aq) → _____(aq) + NO[3]^-(aq) An Arrhenius base is defined as any compound that ______________ in aqueous solution to form _______________ ions. KOH(aq) → K^+(aq) + ________(aq) Salts are compounds that _________________ in aqueous solution releasing ______________________________________ions. KCl → 5. Classifying compounds Using the Arrhenius definition, classify the following examples as acids, bases and salts HBr KCl Mg(OH)[2] H[3] PO[4] HCl HClO KNO[2] Al(OH)[3] HFO[4] KC[2] H [3]O[2] Ba(OH)[2] NaCl 6. Naming acids and bases a) Watch the video^1 and complete the text below Since bases are _____________ compounds, they are named in the usual way: NH[4] OH – Al(OH)[3] – Binary acids consist of __________ elements, the first being ____________. Binary acids are named using the format: _________+(root word of second element)+IC acid Ternary acids consist of _____________ elements. Do not use a prefix. Simply change the ending of the polyatomic ion’s name and add the word ____________. –ate ending becomes ________ and –ite becomes ____________. b) Now name the following acids: HBr H[3] PO[3] HNO[3] HC[2] H[3] O[2] HNO[2 ] H[2] CO[3] HI HClO[2] HF H[2] SO[3] 7. Naming salts a) Read the text below, and according to the information given, name the salts underneath, as in the example. The name of a salt has two parts. The first part comes from the metal in the base or carbonate, or the metal itself if a reactive metal like magnesium or zinc is used. The second part of the name comes from the acid used to make it. The names of salts made from hydrochloric acids end in –chloride, while the name of salts made from sulfuric acid end in –sulfate. metal acid salt 1. sodium hydroxide reacts with hydrochloric acid to make sodium chloride 2. copper oxide hydrochloric acid 3. sodium hydroxide sulfuric acid 4. zinc oxide sulfuric acid 5. ammonia hydrochloric acid b) Write formulas of the reactions above 1. 2. 3. 4. 5. 8. Give formulas of these acids, bases and salts boron silicide magnesium phosphide sodium hydroxide zinc hydroxide iron(III)chloride aluminium sulfide sulfuric acid sulfurous acid 9. Chemistry quiz^2 ^ 1. A solution has a pH of 4 – what does this mean? It is acidic. It is neutral. It is alkaline. 2. Which of the statements below is correct? Bases are acids that dissolve in water. Bases are alkalis that dissolve in water. Alkalis are bases that dissolve in water. 3. A liquid has a pH of 7. What does this tell you about the liquid? It is water. It is sodium chloride solution. It is neutral. 4. Which salt is made when calcium carbonate reacts with hydrochloric acid? sodium chloride calcium chloride calcium sulphate 5. Which pair of substances will react together to make copper sulfate? copper and sulfuric acid copper oxide and sulfuric acid copper oxide and hydrochloric acid 6. Which is the correct order of methods for making a salt from an acid and an insoluble base? filtration è evaporation è neutralisation neutralisation è evaporation è filtration neutralisation è filtration è evaporation Week 13 - Acids and Bases – Vocabulary acid (n) kyselina binary acid (adj+n) binární kyselina ternary acid (adj+n) ternární kyselina acidic (adj) kyselý acidity (n) kyselost alkaline / basic (adj) zásaditý base / alkali (n) zásada alkalinity / basicity (n) zásaditost high alkaline vysoce zásaditý neutral (adj) neutrální salt (n) sůl pH scale stupnice pH introduce a new theory představit novou teorii aqueous solution (adj+n) vodný roztok dissociate (v) štěpit se, disociovat dissolve in water rozpouštět se ve vodě polyatomic ion (adj+n) víceatomový iont ionic compound (adj+n) iontová sloučenina ionization (n) ionizace reactive metal (adj+n) reaktivní kov neutralisation (n) neutralizace filtration (n) filtrace carbonate (n) uhličitan behaviour (n) chování Sources: ^1 Available at www.gpb.org/chemistry-physics/chemistry/1101, visited on October 18, 2011 ^2 Available at http://www.bbc.co.uk/apps/ifl/schools/gcsebitesize/science/quizengine?quiz=add_aqa_acidsbasestest&t emplateStyle=sciencehttp://www.innovations.gatech.edu/bioremediation/avindex.php Lesson adapted from Agnieszka Suchomelová-Polomská. ^