The following compounds are heated in air. In which case will be the mass of solid substance in the test tube is higher after heating than it was initially?NaHCO3Al(OH)3I2CaAu
Question
The following compounds are heated in air. In which case will be the mass of solid substance in the test tube is higher after heating than it was initially?NaHCO3Al(OH)3I2CaAu
Solution
The mass of a solid substance in a test tube after heating would be higher than it was initially if the substance reacts with the oxygen in the air to form a new compound. This is known as oxidation.
Let's consider each compound:
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NaHCO3 (Sodium bicarbonate): When heated, it decomposes to form sodium carbonate, water, and carbon dioxide. The reaction is: 2NaHCO3 → Na2CO3 + H2O + CO2. The products are a solid (sodium carbonate), a liquid (water), and a gas (carbon dioxide). The gas will escape the test tube, so the mass of the solid in the test tube will decrease.
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Al(OH)3 (Aluminium hydroxide): When heated, it decomposes to form aluminium oxide and water. The reaction is: 2Al(OH)3 → Al2O3 + 3H2O. The product is a solid (aluminium oxide) and a gas (water vapor). The gas will escape the test tube, so the mass of the solid in the test tube will decrease.
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I2 (Iodine): When heated, it sublimates, which means it changes directly from a solid to a gas without becoming a liquid. The gas will escape the test tube, so the mass of the solid in the test tube will decrease.
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Ca (Calcium): When heated in air, it reacts with oxygen to form calcium oxide. The reaction is: 2Ca + O2 → 2CaO. Both the reactant (calcium) and the product (calcium oxide) are solids, so the mass of the solid in the test tube will increase.
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Au (Gold): Gold is a noble metal and does not react with oxygen when heated. So, the mass of the solid in the test tube will remain the same.
So, the mass of the solid substance in the test tube will be higher after heating than it was initially in the case of Calcium (Ca).
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