Blue Light Dissolved Oxygen

Fiber Optic Oxygen Sensors from Ocean Optics

Fiber Optic Oxygen Sensors are phase fluorometer-coupled chemical sensors for full spectral analysis of dissolved and gaseous oxygen pressure. A fluorescence method is used to measure the partial pressure of dissolved or gaseous oxygen.

A Fiber Optic Oxygen Sensor system will change the way you work. Because the probe consumes no oxygen, it can be used in continuous contact with viscous samples so that continuous stirring is no longer required. Now that there is an alternative to the oxygen electrode, changing membranes and filling solutions can be avoided.

Oxygen Sensor System - Sample Setup

Optical fiber carries excitation light produced by the blue LED to the thin-film coating at the probe tip. Fluorescence generated at the tip is collected by the probe and carried by the optical fiber to the phase fluorometer. When oxygen in the gas or liquid sample diffuses into the thin-film coating, it quenches the fluorescence. The degree of quenching correlates to the level of oxygen pressure.

Production of copper(I) oxide - LanthanumK's Blog

You will need:

Sodium carbonate

Sodium citrate

Copper sulfate

Copper(II) chloride

Sulfur dioxide

Aluminium

Ammonia

In this page ( http://lanthanumkchemistry.over-blog.com/article-experiments-with-copper-i-chloride-76297411.html ), the fourth experiment showed that microcrystalline copper(I) oxide was formed when copper(I) chloride was reacted wtih a strong alkali. There is another form of copper(I) oxide though, that is red.

Method 1: Produce a solution of Benedict's reagent by adding 100 mg of sodium carbonate, 173 mg of sodium citrate, and 17.3 mg of copper sulfate pentahydrate to 1 mL of water. Add some glucose, fructose, or sucrose. The sucrose must have previously been heated with hydrochloric acid, or it will not work. The blue solution should turn dark red. Add water to the solution to dissolve any excess sugar and filter the precipitate.

Method 2: React a solution of copper(II) chloride with sulfur dioxide. This will make copper(I) oxide.

Method 3: This method has been disputed. A test is done to determine whether this forms copper(I) oxide or copper metal. Make a solution of copper(II) chloride (how to make copper(II) chloride is shown at http://lanthanumkchemistry.over-blog.com/article-how-to-make-copper-ii-chloride-76079848.html ) and add aluminium foil. The test tube gets warm, the aluminium fizzes, a red precipitate forms, and the green color fades. A potential reaction can be aluminium + copper(II) chloride + water = hydrogen + copper(I) oxide + aluminium chloride. Another potential reaction is aluminium + copper(II) chloride + water = aluminium hydroxide + copper + hydrogen + aluminium chloride.

You can do two chemical tests to see which one is right. Test 1: Look at the colorless solution, assuming you have added enough aluminium foil. Is it turbid and thick, or thin and clear like water? Aluminium hydroxide in water makes a gelatin-like mass, while aluminium chloride makes a normal solution.

Test 2: Add household ammonia to a test tube up to the brim. Add the red precipitate to the ammonia and close the test tube, making sure no air is trapped inside. There is still some dissolved oxygen in the ammonia, though. Let it sit overnight. In the morning, it should be light blue from the reaction with the dissolved oxygen. Filter it and add the solution to a beaker. Cover the beaker to prevent excess evaporation. Let it sit for a day. If it turns bright blue, that means the red precipitate is copper(I) oxide. If it does not change much, that means the red precipitate is copper metal. If the results are not clear, it could be a mixture of both.

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