Test for hydrogen Result Place a lighted splint in a test tube of the gas Gas burns with a squeaky 'pop' Oxygen Oxygen is usually made by the decomposition of hydrogen peroxide. Test for oxygen Result Place a glowing splint in a test tube of the gas The splint relights Chlorine Chlorine is usually seen as one of the products from electrolysis of chloride salt solutions. There are two types of litmus paper: red litmus, usually used to test for alkalis blue litmus, usually used to test for acids The test for chlorine can use either type of litmus paper, but blue litmus paper is used most commonly.
Test for chlorine Result Place damp blue litmus paper in a test tube of the gas The blue litmus paper is bleached This test shows that chlorine is a powerful bleach.
Place a lighted splint in a test tube of the gas. Gas burns with a squeaky 'pop'. This explains how the test for chlorine works. The acidic solution formed on the damp litmus paper turns the indicator red. Then the bleach turns the red colour to white. Group 7 - physical properties Group 7 contains non-metal elements placed in a vertical column on the right of the periodic table. Group 7 is on the right-hand side of the periodic table, next to group 0 The halogens show trends in their physical and chemical properties.
Physical properties The halogens exist as simple molecules. This is because, going down group 7: the molecules become larger the intermolecular forces become stronger more energy is needed to overcome these forces Question The graph shows the melting and boiling points of the first four group 7 elements.
This is because an alkali is a base and has the property of turning red litmus paper or red litmus solution to blue. Litmus paper indicates the pH of a solution. Red litmus paper will turn blue in the presence of bases alkaline solutions. A black color indicates that a chemical reaction is taking place with the litmus dye or paper, and this does not provide any information on pH. The paper may also turn white in the presence of strong bleaching agents such as chlorine or peroxides.
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The acid-base environment alters the pi conjugated system and causes a shift in absorbance, causing colour change. The HOCl is the bleach in the reaction, and it probably functions by destroying the extended pi conjugated system. Take the tour to get familiar with this site. For more information in general have a look at the help center. I have converted your answer into a comment for now. Add a comment.
Active Oldest Votes. As I mentioned earlier litmus is a mixture of dyes CAS number: The acid-base indicator properties of litmus are primarily due to 7-hydroxyphenoxazone chromophore pictured below The answer you linked to discusses the acid-base indication mechanism in some detail, so I shall skip over that.
Improve this answer. Did I understand you correct, that there is no reaction with HOCl, but instead there is a reaction with Cl2, followed by reaction with H2O?
The reaction of chlorine you put down with water in your question is reversible.
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