Properties of Gases - Lab Report Example

?Joe Smith Experiment 2 14 October Properties of gases Purpose of the experiment The experiment was meant to identify various gases by investigating their physical and chemical properties. Introduction Some chemical reactions or chemical decomposition reactions result in the production of gaseous products. For instance, hydrogen gas can be prepared in the laboratory through the reaction of a reactive metal and a strong acid. Zinc metal and dilute hydrochloric acid are the preferred reagents for the production of hydrogen gas in the laboratory (Hill, Graham, and John 25). The reaction between zinc metal and dilute hydrochloric acid is as follows: Zn(s) + 2HCl (aq) ZnCl2 (aq) + H2 (g) Oxygen gas can be produced by decomposing hydrogen peroxide in the presence of Manganese (IV) Oxide as a catalyst (Hill, Graham, and John 34). The decomposition of hydrogen peroxide is as shown below: H2O2 (l) MnO2 H2O (l) + O2 (g) Carbon dioxide gas can be generated through the reaction of a metal hydrogen carbonate or a metal carbonate and dilute mineral acid (Hill, Graham, and John 31). The reaction between sodium hydrogen carbonate and dilute hydrochloric acid is as shown below: NaHCO3(s) + HCl (aq) NaCl (aq) + CO2 (g) + H2O (l) The presence of gaseous products can be tested by use of appropriate confirmatory tests. Oxygen gas is characterized by rekindling a glowing splint. Hydrogen gas burns with a ‘pop’ sound in the presence of air. Carbon dioxide gas forms a white suspension when bubbled through lime water (Hill, Graham, and John 27). Therefore, the presence of various gases can be detected by investigating their physical and chemical properties. Procedure Preparation and test for Hydrogen gas A small piece of zinc metal was put into a test tube containing dilute hydrochloric acid. The test tube was capped with a rubber stopper with a straight, short plastic delivery tubing though its center. The test tube was placed into one of the wells of the 24-well plate. A little tissue paper was used to support the test tube to stand up straight. A wide-neck pipette bulb was filled completely with water and was placed on the gas delivery tube of the test tube. The well plate with test tube assembly was placed in a pie tin because some water would overflow during the displacement of the water in the pipette bulb. When the water in the pipette bulb had been completely displaced by hydrogen, the pipette was removed in an inverted position, and a thumb was placed over its opening to keep any gaseous content from escaping. A match was lit, and a small portion of the pipette content was squeezed into the flame from a distance of about 1 cm. Observations were made, and the results were recorded. The wide-neck pipette bulb was marked with a marker pen on the outside into three equal parts. The marked pipette bulb was filled with water, inverted and was set onto the gas generation tube. When about two thirds of the bulb was occupied with the produced gas, the bulb was removed while in an inverted position. The pipette bulb was set with its mouth facing down into one of the wells of the 24-well plate for later use. The test tube was disassembled and was rinsed well with water. Preparation and test for oxygen gas Few pieces of Manganese metal were placed into a second test tube. Enough of 3% Hydrogen peroxide was added to fill the test tube almost to the top. A rubber stopper with plastic gas delivery tube through its center was inserted into the test tube, and the test tube was placed into a well of the 24-well plate. The test tube was wedged into a straight position by use of a paper tissue. The reaction was observed, and the observation was recorded. A comparison was made between the reaction in the first part of the experiment and the reaction in the second part of the experiment. Another wide-neck pipette bulb was completely filled with water. The pipette was inverted and was placed on the delivery tube of the test tube. When the water had been completely displaced by the produced gas in the collection pipette, the pipette was removed, and a thumb was placed at its mouth to prevent the gas from escaping. A wooden toothpick was lit, extinguished and was quickly inserted into the gas-filled pipette. Observations were recorded. Mixture of hydrogen and oxygen The partially filled pipette bulb that was saved from Part 1 was placed on the oxygen generation test tube that was created in Part 2. Enough oxygen was collected until all the water had been displaced. The content of the bulb was then 1/3 oxygen and 2/3 hydrogen. A match was lit and was placed very close to the mouth of the gas filled pipette that was held horizontally. The contents of the pipette were gently squeezed into the flame and observations were made. The set up was disassembled, and the apparatus were thoroughly rinsed for future use. Preparation and test for carbon Dioxide gas 0.5 to 1.0 ml of limewater were put into a well of the 24-well plate. Half a teaspoon sodium bicarbonate was placed in the bottom of the generation test tube. The test tube was then held over a pie tin, and a pipette full of white vinegar was added to sodium bicarbonate. As soon as the vinegar and sodium bicarbonate were combined, they reacted vigorously and some content overflew. Once the overflow had stopped, the stopper with a copper and plastic gas delivery tube was inserted into the test tube. The open end of the gas delivery tube was placed into the limewater in the well. Observations were recorded. 0.5 to 1.0 ml of Bromothymol blue were put into another well of the 24-well plate. Another test tube with vinegar and sodium bicarbonate was set up, but this time the open end of the copper and plastic gas delivery tube was placed into the Bromothymol blue in the well. Observations were recorded. A match was lit, and the flame was inserted into the upper part of the gas generation test tube. Observations were recorded. 0.5 to 1.0 ml of limewater were put into another well of the 24-well plate. A small piece of Alka Seltzer tablet was crumbled into the generation test tube. 1 pipette full of water was added to the crumbled Alka Seltzer and a stopper with a copper and plastic gas delivery tube was immediately inserted into the generation test tube. The open end of the delivery tube was placed into the limewater in the well. Observations were recorded. 0.5 to 1.0 ml of limewater were put into a test tube. A straw was inserted into the limewater, and air was blown gently into it for a few seconds. Observations were recorded. Results and Discussion Properties of gases were used to identify various gases. Hydrogen gas, carbon dioxide gas, and oxygen gas were prepared, and their properties were investigated in this experiment. The reaction of zinc metal and dilute hydrochloric acid produced hydrogen gas which was collected by the upward delivery method, over the surface of water. Hydrogen gas produced a ‘pop’ sound when it was burned in air. Hydrogen peroxide liquid decomposed into oxygen gas and water in the presence of manganese dioxide. Oxygen gas was collected by the downward displacement of water method, over the surface of water. Gas generator test tubes were filled with chemicals almost to the top to ensure that the generated gases were not mixed with air. The ability to relight a glowing splint was the major chemical property of oxygen that was used in its identification. The mixture of hydrogen and oxygen was found to burn explosively with the formation of water vapor. This reaction can be represented by the equation below: O2(s) + H2 (aq) Heat H2O (g) The reaction between sodium bicarbonate and white vinegar produced carbon dioxide gas and water. The gas was collected by down ward delivery method because it was heavier than air. Carbon dioxide gas formed a white suspension with limewater due to the formation of insoluble calcium carbonate. Carbon dioxide gas also extinguished a burning wooden toothpick which was evident that it does not support combustion. Carbon dioxide gas also turned the green Bromothymol blue into a yellow color. The reaction between Alka Seltzer tablet and water produced carbon dioxide gas which formed a white suspension with limewater. When air was blown into limewater, a white was formed because the air contained carbon dioxide gas. Conclusion Chemical properties of oxygen gas, carbon dioxide gas, and hydrogen gas were used to identify the gases after they were produced. During the laboratory preparation of oxygen, carbon dioxide, and hydrogen gases, the generation test tubes were completely filled with chemicals to ensure that the resultant gases were not mixed with air. All the generated gases were collected when the generation test tubes were filled with chemicals almost to the top (Hill, Graham, and John 27). QUESTIONS: A. Give two reasons why we fill the gas generator test tubes almost to the top with chemicals. This was to ensure that the resultant gases were not mixed with air. All the generated gases were collected when the generation test tubes were filled with chemicals almost to the top. B. What happens to the zinc in the hydrogen generation experiment?  Zinc metal was reacted with dilute hydrochloric acid to form hydrogen gas and zinc chloride solution. Therefore, zinc ionized and displaced chloride ions from the dilute hydrochloric acid. C. What happens to the manganese in the oxygen generation experiment?  Manganese metal was oxidized into manganese dioxide. The manganese dioxide catalyzed the decomposition of hydrogen peroxide into oxygen gas and water. D. Write a balanced equation for the reaction between O2 and H2.  O2(s) + 2H2 (aq) Heat 2H2O (g) E. What is the function/purpose of the Bromothymol blue in the CO2 experiment?  Bromothymol blue was used to show that carbon dioxide gas is an acidic gas. F. Bromothymol blue is blue in the presence of basic solutions, and yellow in the  presence of acidic solutions. If your solution is a murky green, what might you assume  about the solution?  Bromothymol blue is murky green in neutral solutions. G. Gas Flame Reaction Glowing Splint Limewater Reaction Bromothymol blue Reaction Hydrogen Popping sound was heard N/A N/A N/A Oxygen Supported burning Rekindled a glowing splint N/A N/A Hydrogen and Oxygen Explosion was heard N/A N/A N/A Carbon Dioxide The flame was extinguished N/A A white suspension was formed The green solution turned yellow Alka Seltzer The flame was extinguished N/A A white suspension was formed The green solution turned yellow Breath The flame was extinguished N/A A white suspension was formed The green solution turned yellow Works Cited Hill, Graham, and John S. Holman. Chemistry in context. Wyd. 5. ed. Cheltenham: Nelson Thornes, 2000. Print. Read More