1. Dilute hydrochloric acid was used to react with various substances including copper oxide, iron nails, magnesium strips, and egg shells. These reactions all produced observable changes and gaseous products like hydrogen and carbon dioxide. 2. The acid reacted with the copper oxide on a coin, removing the layer to expose bare copper. Reactions with iron nails removed rust and bubbles formed, while magnesium vigorously reacted with bubbles. Egg shells reacted to produce carbon dioxide bubbles. 3. Additional details are provided about the chemical reactions, products, and observations for each substance tested with the hydrochloric acid.

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2. -The oxidised (Copper II Oxide) layer on the copper coin reacted away to expose the pink metal. - C opper II O xide (CuO) is a bla ck solid with an ionic structure which melts above 1200 °C with some loss of oxygen. It can be formed by heating copper in air: 2 Cu + O2 -> 2 CuO - Copper(II) oxide is a basic oxide, so it dissolves in mineral acids such as hydrochloric acid, sulfuric acid or nitric acid to give the corresponding copper(II) salts: CuO + 2 HCl -> CuCl2 + H2O ( same as above ) - Copper (II) oxide + Hydrochloric acid -> Copper (II) chloride + water - Copper (II) chloride is prepared by the action of hydrochloric acid on copper (II) oxide copper (II) hydroxide or copper (II) carbonate CuO (s olid) + 2 HCl (aqueous) -> CuCl2(aqueous) + H2O(liquid) (BALANCED) (Click on the tube to move on) 1) Place an oxidised copper coin in a beaker of dilute hydrochloric acid for a few minutes. Remove the coin from the acid thereafter. Observations: Skip effects

3. -The oxidised (Copper II Oxide) layer on the copper coin reacted away to expose the pink metal. - C opper II O xide (CuO) is a bla ck solid with an ionic structure which melts above 1200 °C with some loss of oxygen. It can be formed by heating copper in air: 2 Cu + O2 -> 2 CuO - Copper(II) oxide is a basic oxide, so it dissolves in mineral acids such as hydrochloric acid, sulfuric acid or nitric acid to give the corresponding copper(II) salts: CuO + 2 HCl -> CuCl2 + H2O ( same as above ) - Copper (II) oxide + Hydrochloric acid -> Copper (II) chloride + water - Copper (II) chloride is prepared by the action of hydrochloric acid on copper (II) oxide copper (II) hydroxide or copper (II) carbonate CuO (s olid) + 2 HCl (aqueous) -> CuCl2(aqueous) + H2O(liquid) (BALANCED) (Click on the tube to move on) 1) Place an oxidised copper coin in a beaker of dilute hydrochloric acid for a few minutes. Remove the coin from the acid thereafter. Observations:

4. 1) Place an oxidised copper coin in a beaker of dilute hydrochloric acid for a few minutes. Remove the coin from the acid thereafter. Observations: (Click on the tube to move on)

5. Explanation: Hydrogen chloride (HCl) can dissociate ( i.e., ionize) only once to give up one H+ ion (a single proton). In aqueous hydrochloric acid, the H+ joins a water molecule to form a hydronium ion, H3O HCl + H2O -> H3O+ + Cl− The other ion formed is Cl−, the chloride ion. Hydrochloric acid can therefore be used to prepare salts called chlorides , such as sodium chloride. Hydrochloric acid is a Hydrochloric acid is frequently used in chemical analysis to prepare ("digest") samples for analysis. Concentrated hydrochloric acid dissolves many metals and forms oxidized metal chlorides and hydrogen gas, and it reacts with basic compounds such as calcium carbonate or copper (II) oxide, forming the dissolved chlorides that can be analyzed strong acid, since it is essentially completely dissociated in water. (Click on the tube to move on) Skip effects

6. Explanation: Hydrogen chloride (HCl) can dissociate ( i.e., ionize) only once to give up one H+ ion (a single proton). In aqueous hydrochloric acid, the H+ joins a water molecule to form a hydronium ion, H3O HCl + H2O -> H3O+ + Cl− The other ion formed is Cl−, the chloride ion. Hydrochloric acid can therefore be used to prepare salts called chlorides , such as sodium chloride. Hydrochloric acid is a Hydrochloric acid is frequently used in chemical analysis to prepare ("digest") samples for analysis. Concentrated hydrochloric acid dissolves many metals and forms oxidized metal chlorides and hydrogen gas, and it reacts with basic compounds such as calcium carbonate or copper (II) oxide, forming the dissolved chlorides that can be analyzed strong acid, since it is essentially completely dissociated in water. (Click on the tube to move on)

7. Explanation: (Click on the tube to move on)

8. 2) Place a rusted iron nail in beaker of dilute hydrochloric acid for a few minutes. Remove the nail from the acid thereafter. Observations: -Rust (Fe2O3) on iron nail disappears, exposing the silver-colored metal, which is actually iron. -Rust is a umbrella ter m for a variety of iron oxides, formed by the reaction of iron and oxy g en in the presence of water or air moisture. Rust has no be neficial use, as it is only known for harming metals. For example, it can completely degrade iron , deform the shape of its original structure , and result in brown or black water due to rusting in pipes -Bubbles of colourless gas (Hydrogen) formed on the iron nail. -Word equation: Reaction with rust - Hydrochloric acid + Iron Oxide -----> Iron Chloride + Water -Chemical equation: 6 HCl (aq) + Fe2O3 (s) --> 2 FeCl3 (aq) + 3 H2O (l) -Word equation: Reaction with pure iron - Iron + Hydrochloric acid ------> Iron Chloride + Hydrogen -Chemical equation: Fe (s) + 2 HCl (aq) ---> FeCl2 (aq) + H2 (g) (Click on the tube to move on) Skip effects

9. 2) Place a rusted iron nail in beaker of dilute hydrochloric acid for a few minutes. Remove the nail from the acid thereafter. Observations: -Rust (Fe2O3) on iron nail disappears, exposing the silver-colored metal, which is actually iron. -Rust is a umbrella ter m for a variety of iron oxides, formed by the reaction of iron and oxy g en in the presence of water or air moisture. Rust has no be neficial use, as it is only known for harming metals. For example, it can completely degrade iron , deform the shape of its original structure , and result in brown or black water due to rusting in pipes -Bubbles of colourless gas (Hydrogen) formed on the iron nail. -Word equation: Reaction with rust - Hydrochloric acid + Iron Oxide -----> Iron Chloride + Water -Chemical equation: 6 HCl (aq) + Fe2O3 (s) --> 2 FeCl3 (aq) + 3 H2O (l) -Word equation: Reaction with pure iron - Iron + Hydrochloric acid ------> Iron Chloride + Hydrogen -Chemical equation: Fe (s) + 2 HCl (aq) ---> FeCl2 (aq) + H2 (g) (Click on the tube to move on)

10. 2) Place a rusted iron nail in beaker of dilute hydrochloric acid for a few minutes. Remove the nail from the acid thereafter. Observations: (Click on the tube to move on)

11. Explanation: There are two chemical reactions taking place. First the Hydrochloric acid reacts with the rust coating the nail. This exposes the grey Iron metal, which can then react. The gas produced is Hydrogen , as seen in the last chemical reaction. It is the colourless gas that is seen coming out from the bubbles. (Click on the tube to move on) Skip effects

12. Explanation: There are two chemical reactions taking place. First the Hydrochloric acid reacts with the rust coating the nail. This exposes the grey Iron metal, which can then react. The gas produced is Hydrogen , as seen in the last chemical reaction. It is the colourless gas that is seen coming out from the bubbles. (Click on the tube to move on)

13. Explanation: (Click on the tube to move on)

14. 3) Place a magnesium strip in a beaker of dilute hydrochloric acid. Observations: -Vigorous bubbling of colourless gas (Hydrogen). - Strip dissolves in the acid after vigorous reaction. -Word equation: Magnesium + Hydrochloric acid -> Magnesium chloride + Hydrogen gas -Chemical equation: Mg (s) + 2HCl (aq) -> MgCl2 (aq)+ H2 (g) -Initial dirty grey coating over magnesium strip (Oxide) disappears. -The magnesium strip dissolved in the beaker of dilute hydrochloric acid because Mg2+ is located higher than H+ in the electrochemistry series and Mg2+ is more electropositive than H+ , thus the reaction occured (Click on the tube to move on) Skip effects

15. 3) Place a magnesium strip in a beaker of dilute hydrochloric acid. Observations: -Vigorous bubbling of colourless gas (Hydrogen). - Strip dissolves in the acid after vigorous reaction. -Word equation: Magnesium + Hydrochloric acid -> Magnesium chloride + Hydrogen gas -Chemical equation: Mg (s) + 2HCl (aq) -> MgCl2 (aq)+ H2 (g) -Initial dirty grey coating over magnesium strip (Oxide) disappears. -The magnesium strip dissolved in the beaker of dilute hydrochloric acid because Mg2+ is located higher than H+ in the electrochemistry series and Mg2+ is more electropositive than H+ , thus the reaction occured (Click on the tube to move on)

16. 3) Place a magnesium strip in a beaker of dilute hydrochloric acid. Observations: (Click on the tube to move on)

17. Explanation: -If one adds Magnesium metal (Mg) into hyrdochloric acid (HCl), the Magnesium will dissolve and will form bubbles of hydrogen gas (H2). When the Mg dissolves, it forms magnesium ions with a +2 charge (Mg2+), and when the hydrogen atoms form H2 gas, they leave behind chloride ions, Cl-. -Mg(s) + 2 HCl(aq) --> Mg2+(aq) + 2Cl-(aq) + H2(g) -A very similar reaction will happen if one adds Mg to any strongly acidic solution, such as sulphuric acid. Here the reaction is: -Mg(s) + H2SO4(aq) --> Mg2+(aq) + SO42-(aq) + H2(g) (Click on the tube to move on) Skip effects

18. Explanation: -If one adds Magnesium metal (Mg) into hyrdochloric acid (HCl), the Magnesium will dissolve and will form bubbles of hydrogen gas (H2). When the Mg dissolves, it forms magnesium ions with a +2 charge (Mg2+), and when the hydrogen atoms form H2 gas, they leave behind chloride ions, Cl-. -Mg(s) + 2 HCl(aq) --> Mg2+(aq) + 2Cl-(aq) + H2(g) -A very similar reaction will happen if one adds Mg to any strongly acidic solution, such as sulphuric acid. Here the reaction is: -Mg(s) + H2SO4(aq) --> Mg2+(aq) + SO42-(aq) + H2(g) (Click on the tube to move on)

19. Explanation: (Click on the tube to move on)

20. 4) Place some egg shells in a beaker of dilute hydrochloric acid. Observations: -The egg shell is made up of approximately 95% Calcium Carbonate (CaCO3) and the remaining 5% of the egg shell is made up of proteins. -Air bubbles are observed coming from the egg shell -The colorless gas produced is Carbon dioxide (CO2) and the chemical test for this gas is the limewater (CaOH) test. The gas is pumped into limewater (CaOH) and if it turns cloudy, the gas is Carbon dioxide (CO2). -Calcium carbonate (CaCO3) in egg shell reacts with Hydrochloric acid (HCl) to form Carbon dioxide (CO2), water (H2O) and Calcium chloride (CaCl2). 2HCl +CaCO3 -> CaCl2 +CO2 +H2O (Click on the tube to move on) Skip effects

21. 4) Place some egg shells in a beaker of dilute hydrochloric acid. Observations: -The egg shell is made up of approximately 95% Calcium Carbonate (CaCO3) and the remaining 5% of the egg shell is made up of proteins. -Air bubbles are observed coming from the egg shell -The colorless gas produced is Carbon dioxide (CO2) and the chemical test for this gas is the limewater (CaOH) test. The gas is pumped into limewater (CaOH) and if it turns cloudy, the gas is Carbon dioxide (CO2). -Calcium carbonate (CaCO3) in egg shell reacts with Hydrochloric acid (HCl) to form Carbon dioxide (CO2), water (H2O) and Calcium chloride (CaCl2). 2HCl +CaCO3 -> CaCl2 +CO2 +H2O (Click on the tube to move on)

22. 4) Place some egg shells in a beaker of dilute hydrochloric acid. Observations: (Click on the tube to move on)

23. Explanation: When Calcium carbonate (CaCO3) in the egg shell reacts with Hydrochloric acid (HCl), t he Hydrochloric acid decomposes into Hydrogen (H+) and Chlorine (Cl-) and the Calcium carbonate decomposes into Calcium (Ca2+), Carbon (C4+) and Oxygen (O2-). Then, Hydrogen (H+) bonds with Oxygen (O2-) to form water (H2O), Calcium (Ca2+) bonds with Chloride (Cl-) to form Calcium chloride (CaCl2) and Carbon (C4+) bonds with Oxygen (O2-) to form Carbon dioxide (CO2). 2HCl+CaCO3->2H+Cl2-+Ca2++C4++O2--> CaCl2 +CO2 +H2O (Click on the tube to move on) Skip effects

24. Explanation: When Calcium carbonate (CaCO3) in the egg shell reacts with Hydrochloric acid (HCl), t he Hydrochloric acid decomposes into Hydrogen (H+) and Chlorine (Cl-) and the Calcium carbonate decomposes into Calcium (Ca2+), Carbon (C4+) and Oxygen (O2-). Then, Hydrogen (H+) bonds with Oxygen (O2-) to form water (H2O), Calcium (Ca2+) bonds with Chloride (Cl-) to form Calcium chloride (CaCl2) and Carbon (C4+) bonds with Oxygen (O2-) to form Carbon dioxide (CO2). 2HCl+CaCO3->2H++Cl2-+Ca2++C4++O2--> CaCl2 +CO2 +H2O (Click on the tube to move on)

25. Explanation: (Click on the tube to move on)

26. 5) Gently warm a mixture of ammonium nitrate crystals with aqueous sodium hydraxide. Test the gas evolved with red litmus paper. Observations: -Moist red litmus paper turns blue. -A gas is produced. The gas produced from heating the mixture is ammonia ( NH3 ), it is a colourless gas and has a ungent smell.When ammonia gas passed through Chloroplatinic solution (H2PtCl6) gives a yellow colouration. Word equation: Ammonium nitrate + sodium hydroxide  Ammonia + water + sodium nitrate Chemical equation: NH4NO3 + NaOH ------> NH3 + H20 + NaNO3 (Click on the tube to move on) Skip effects

27. 5) Gently warm a mixture of ammonium nitrate crystals with aqueous sodium hydraxide. Test the gas evolved with red litmus paper. Observations: -Moist red litmus paper turns blue. -A gas is produced. The gas produced from heating the mixture is ammonia ( NH3 ), it is a colourless gas and has a ungent smell.When ammonia gas passed through Chloroplatinic solution (H2PtCl6) gives a yellow colouration. Word equation: Ammonium nitrate + sodium hydroxide  Ammonia + water + sodium nitrate Chemical equation: NH4NO3 + NaOH ------> NH3 + H20 + NaNO3 (Click on the tube to move on)

28. 5) Gently warm a mixture of ammonium nitrate crystals with aqueous sodium hydraxide. Test the gas evolved with red litmus paper. Observations: (Click on the tube to move on)

29. Explanation: (Click on the tube to move on) The litmus paper should be moist because moist litmus paper reacts more rapidly against gas. Since we are testing the litmus paper against ammonia which is a gaseous type of substance, the litmus paper should be moist. We should also warm the mixture because b y warming the mixture we, the temperature of the mixture will rise and produced a type of gas called ammonia (NH3). Without warming the mixture no gas will appear out of the mixture. Litmus paper is a well-known tool to identify whether a substance is considered an acid or base. Blue litmus paper turns red under acidic conditions. Red litmus paper turns blue under basic (alkaline) conditions. By heating the mixture it produces salt which in this case is sodium nitrate, water and ammonia. Red litmus paper is tested against ammonia gas. The litmus paper turns blue indicating that ammonia is a base. Skip effects

30. Explanation: (Click on the tube to move on) The litmus paper should be moist because moist litmus paper reacts more rapidly against gas. Since we are testing the litmus paper against ammonia which is a gaseous type of substance, the litmus paper should be moist. We should also warm the mixture because b y warming the mixture we, the temperature of the mixture will rise and produced a type of gas called ammonia (NH3). Without warming the mixture no gas will appear out of the mixture. Litmus paper is a well-known tool to identify whether a substance is considered an acid or base. Blue litmus paper turns red under acidic conditions. Red litmus paper turns blue under basic (alkaline) conditions. By heating the mixture it produces salt which in this case is sodium nitrate, water and ammonia. Red litmus paper is tested against ammonia gas. The litmus paper turns blue indicating that ammonia is a base.

31. Explanation: (Click on the tube to move on)

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