The first method is naturally burning with fire. The copper ring will turn black, while gold will not change color. However, our usual lighter temperature cannot be reached. You can try to use the fire of the gas stove and burn for a few minutes to see. However, this method is not applicable to K gold, which is the identification of 18K gold. The second method can be seen from the jewelry mark. The gold necklace seal is written on M buckle, bracelets and rings marks on the inside. AU750. If the jewelry is copper gold, some are not sighed, and some will be marked with English GK, which means gold -plated. The third method is to throw the ground to listen to the sound. This method Xiao Zheng once specifically shot a video to explain. The sound of copper has echo and the sound is crispy. The sound of the gold was no echo, and the sound of the sound was stuffy. The fourth method is to see the hardness, the hardness of the gold, such as the gold ring, the gold can be pinched slightly, but because the copper is too hard, it is impossible to pinch. The fifth method, soaking and identifying with sulfuric acid, or nitric acid, the copper jewelry is soaked with sulfuric acid for a long time, and the chemical reaction color will turn black, and gold will not. If the copper jewelry will develop a severe chemical reaction immediately when you encounter nitric acid, gold will not.
Add dilute sulfuric acid The reaction of sulfuric acid and copper reaction to generate sulfur dioxide. 2H2SO4 CU == CUSO4 2H2O SO2 ↑ and sulfuric acid discomfort with gold. Therefore, it can be judged accordingly. Specifically, two empty bottles are taken, put inward and gold in it, and then pour sulfuric acid into two bottles to observe the reaction. The history of brass: The earliest copper products found in the world are mainly in West Asia. For example, the Zawei Chemi area in Iraq, there are copper decorations. Nine thousand BC. The Ali Kashgar area in western Iran has also been found. Copper decorations have also been found. The age is from 9,000 BC to 7,000 BC; copper needles and copper cone unearthed from the Chayenen site in southern Turkey. Eight thousand BC. These copper products are all natural red copper products, not copper obtained through smelting ore. In using pure copper to smelting copper ore obtained pure copper, and then smelting bronze alloys, humans have experienced a long period of exploration. Sparkling space -time tunnel.
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