it result to the formation of metal sulfates
Put a glass tube into the beaker of water so that it touches the bottom, then drop the crystal down the tube and put your finger over the top of the, then remove the tube gently, leaving the crystal behind in the beaker. After that laugh maniacally at the test tube and you might become an evil genius! Hope this helps! :)
When iodine is heated in a test tube, it sublimates, transitioning directly from a solid to a purple vapor without passing through a liquid phase. This vapor can condense back into solid iodine upon cooling, forming purple crystalline deposits on the cooler parts of the test tube. The characteristic purple color and pungent odor of iodine vapors are also noticeable during the heating process.
In a starch test, water is used in one tube as a control to establish a baseline for comparison. This allows researchers to confirm that any color change in the experimental tube, where starch and iodine are present, is due to the presence of starch rather than other factors. The control helps validate the results, ensuring that the observed reaction is specific to starch reacting with iodine.
Blowing over the mouth of the test tube will create a decrease in air pressure inside the tube. This decrease in pressure will cause the water in the test tube to rise up due to the higher pressure outside the tube. Ultimately, the water level in the test tube will rise as a result of the change in pressure.
When the leaf was removed from the test tube containing methylated spirit, it would typically appear a pale yellow or white. This discoloration occurs because the methylated spirit removes chlorophyll and other pigments from the leaf, effectively bleaching it. This process is often done to prepare the leaf for subsequent testing, such as the iodine test for starch, which would indicate the presence of starch as a blue-black color when iodine is applied.
This is also iodine, as a gas.
Put a glass tube into the beaker of water so that it touches the bottom, then drop the crystal down the tube and put your finger over the top of the, then remove the tube gently, leaving the crystal behind in the beaker. After that laugh maniacally at the test tube and you might become an evil genius! Hope this helps! :)
The purple gas that forms when heating iodine crystals is called iodine vapor.
The purple gas formed when heating solid iodine in a test tube is iodine vapor. Iodine sublimes directly from a solid to a gas when heated, turning into a purple gas that condenses back into solid iodine crystals when cooled.
The starch solution will turn black, while the distilled water will remain brown, the same colour as the iodine. This is actually because water, normally used as a control, does not contain any starch and as we know, the iodine test is highly specific for the presence of starch hence no colour change other than iodine dissolving in water to form an iodine solution contrary to starch which we know complexes with iodine, to form starch-iodine complex forming the blue-black colour observed
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If a burning splint pops in a test tube, it indicates the presence of oxygen. The popping sound is a result of the increased rate of combustion due to the higher oxygen concentration in the test tube.
Use iodine to test a leaf for starch | Plant Physiology | Biology
Blowing over the mouth of the test tube will create a decrease in air pressure inside the tube. This decrease in pressure will cause the water in the test tube to rise up due to the higher pressure outside the tube. Ultimately, the water level in the test tube will rise as a result of the change in pressure.
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A test tube holder is used while heating to protect you from burning your fingers on the hot glass and to help prevent accidental spills or breakage. Holding a test tube directly can result in uneven heating and potentially cause the tube to shatter due to thermal stress.
The air molecules inside the test tube have a higher mobility when heated (they move around more). The collisions between these air molecules create more pressure on the inside of the test tube (force/area, where the force is the result of the increasing collisons and the area is the internal wall of the test tube.) This may result in the pressure inside of the test tube to be greater than the outside atmospheric pressure on the cork (actually atmospheric pressure on the cork and the frictional force on the cork created by the mouth of the test tube). If the internal pressure becomes greater than the external pressure (plus frictional force) the cork will come loose of the test tube.