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Reaction of Acids

Reaction of Acids. Light a Bunsen Burner and adjust it to give a YELLOW flame. Add about 2ml of dilute hydrochloric acid to a test tube and add a few drops of universal indicator: Record the pH

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Reaction of Acids

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  1. Reaction of Acids • Light a Bunsen Burner and adjust it to give a YELLOW flame. • Add about 2ml of dilute hydrochloric acid to a test tube and add a few drops of universal indicator: • Record the pH • Add a piece of magnesium to the acid. To trap the gas released, hold your thumb over the mouth of the test tube until the pressure builds. • Your partner will light the SPLINT with the Bunsen burner and hold it over the test tube QUICKLY after lifting your thumb off releasing gas. • See page 251 to answer questions • Make a table to record your data.

  2. Word equations • When a reaction occurs, we write the reactants, then an arrow followed by the products. • In an acid reaction with metal • Acid + Metal-->Salt + Hydrogen gas • E.g. Hydrochloric acid + Magnesium -->Magnesium Chloride (salt) + Hydrogen gas. • If an acid reacts with a metal bubbles of hydrogen and a salt are made.

  3. Salts Metal name Or Ammonium Non Metal name (S, O, Cl) Or a radical (NO3, SO4, PO4, CO3, HCO3) • Salts are a large group of compounds. • Salts can be recognised by their chemical formulae. • E,g, • Sodium Chloride

  4. Acid reactions • When acids react they make new compounds with predicable names. These new compounds are called salts • Hydrochloric acid: HCl, (H+ , Cl-) • This acid makes CHLORIDES • Sulfuric Acid: H2SO4 (2H+ , SO42-) • This acid makes SULFATES • Nitric Acid: HNO3 (H+ , NO3-) • This acid makes NITRATES

  5. Questions Write a word equation for the reactions you performed today (assuming they all reacted). Suggest why pH increases during the reaction. What happens to the chloride ions after the hydrogen gas is made?

  6. Read the LEFT side of page 253 and answer the questions • In yesterdays experiment we reacted HCl and H2SO4 with zinc, and noticed some bubbling but the reaction didn’t give off a squeaky pop like it did with magnesium. 1) Explain why in terms of reaction rate? 2) How could you speed up the rate of reaction of a dilute acid? • What is the general equation for metals and dilute acids? • How are the different salts named? 5) What is the most common salt? • Write an equation showing the reaction to form this salt • What are some other examples of salts and their uses?

  7. Experiment • Copper Carbonate + Sulfuric acid  Copper Sulfate + Water + Carbon dioxide. • CuCO3 + H2SO4  CuSO4 + H2O + CO2 • We can identify Carbon dioxide gas as it turns limewater cloudy or puts a burning flame out. • The acid turned the green powder blue and the boiling tube began to bubble.

  8. Acids Reacting with Carbonates. • Limestone, marble, washing soda, baking soda are all CARBONATES. • Acids dissolve them with bubbles of gas being made. • General Equation: Acid + Carbonate  Salt + Water + Carbon dioxide. • E.g. Sodium Bicarbonate + Hydrochloric acid  Sodium Chloride + Water + Carbon dioxide. • NaHCO3 + HCl  NaCl + H2O + CO2

  9. Complete these and write the word formula for each. • HCL + CaCO3 _____ + _____ + _____ • HCl + Na2CO3  _____ + _____ + _____ • H2SO4 + CaCO3  ____ + ____ + ____ • NaCO3 + H2SO4  ____ + ____ + ____

  10. Big Bang experiment • Protons will be fired through a 17-mile tunnel under Switzerland and be made to smash into each other. • The first beam has completed its maiden journey through the Large Hadron Collider (LHC) without incident. • The flashing of two white dots on a computer screen indicated that the protons had reached the final point of the world's largest particle accelerator. • This prompted a cheer and the popping of champagne corks - but there was still a long way to go. • Scientists fired up the second beam of protons - one of the building blocks of atoms - several hours later.  • Its journey, which runs in the opposite direction to the first beam, also went off without a hitch. • The experiment is aiming to capture an image of the conditions that existed a billionth of a second after the Big Bang. • Physicist Dr Alan Barr, who is also in Geneva working on the project, told Sky News: "The atmosphere is absolutely electric. Things have gone really smoothly."

  11. Questions – Neutralisation pg 254 1) What causes the intense pain from a jellyfish sting? 2) Describe 2 reasons why they wouldn’t use a strong acid to neutralise the jellyfish sting. 3) Why wouldn’t you use vinegar for a wasp sting. 4) What should you do if you don’t know what has bitten you? 5) Write the word equation for a neutralisation reaction. 6) Why do people add lemon juice to their fish? 7) Describe what indigestion is. 8) Extension: Write the word and chemical equation for the reaction of stomach acid and indigestion tablets containing magnesium hydroxide.

  12. Answers • A basic substance in their sting. • -Because a strong acid may harm you -No-one brings strong acid to the beach! • Because both wasp stings and vinegar are acidic • Treat the sting with ice • Acid + Base  Salt + Water • Because lemon juice neutralises the basic amines in fish giving a more pleasant smell. • Pain from your stomach from it being too acidic, after eating too much or too quickly. • -Hydrochloric acid + Magnesium Hydroxide  Water + Sodium Chloride -2HCl + Mg(OH)2 2H20 + MgCl2

  13. Neutralisation • The reaction between an acid and a base is called NEUTRALISATION • The general reaction is: • Acid + Base  A Salt + Water • The salt is in the solution after the reaction has finished. It can be seen if the water is evaporated. • E.g. H2SO4 + NaOH  Na2SO4 + H2O • Sodium Sulfate is the salt • In neutralisation the H+ from the acid react with OH- from the base to form H20!

  14. Counting the number of atoms • When there is a small subscript number it refers to the amount of atom before the number. • E.g H20 suggests 2 hydrogen atoms + 1 Oxygen atom. (2 + 1 = 3 atoms) • If brackets are present, the small subscript number refers to all the atoms in the brackets • E.g. Ca(OH)2 suggests 1 calcium atom and 2 Oxygen and 2 Hydrogen atoms. 1 + 1 + 2 = 5 atoms • When there is a large number before a formula then it refers to the whole compound. • E.g. 2NaOH suggests 2 sets of (1 Sodium, 1 Oxygen and 1 Hydrogen). 2x(1+1+1)=6 atoms

  15. How many atoms are there in? 1) He 2) O2 3) CO2 4) H2 5) NH3 6) KCl 7) CuSO4 8)H2SO4 9) 3H2O 10) K2CO3 11) Ba(OH)2 12) 2Zn(NO3)2

  16. Answers 1) He = 1 2) O2 = 2 3) CO2 = 34) H2 = 2 5) NH3 = 46) KCl = 2 7) CuSO4 = 6 8)H2SO4 = 7 9) 3H2O = 9 10) K2CO3 = 6 11) Ba(OH)2 = 5 12) 2Zn(NO3)2 = 18

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