A crystalline material containing 30 grams of barium chloride crystals was placed into an oven at 400 degrees c and heated for two hours. It was then cooled and weighed. the new mass was less than before it was heated, containing 20 grams if barium chloride. How is this possible?
The barium chloride must have been a hydrate and the water was driven out of it OR the barium chloride was wet to begin with. I'm sure the first is the answer you want and the person who made up the problem didn't think about the second possibility.
Copper 2 sulfate is a hydrated crystal with a deep blue color. When it is heated the crystals crumble and turn white. Why and how can you return the blue color?
The crystal that contain attached water molecules. while heating, barium chloride produce the water molecules and the water molecules contain the weight and absorb some weight of barium chloride
The decrease in mass of the barium chloride crystals after being heated in the oven can be explained by the process of dehydration.
Barium chloride (BaCl2) crystals can form different types of hydrated salts, meaning they have water molecules trapped within their crystal lattice structure. These water molecules are called water of crystallization.
When the barium chloride crystals are heated, the high temperature causes the water molecules within the crystal lattice to escape in the form of steam or water vapor. This process is known as dehydration.
The chemical reaction for the dehydration of hydrated barium chloride can be represented as follows:
BaCl2 • xH2O (crystals) → BaCl2 (anhydrous) + xH2O (vapor)
In this reaction, "x" represents the number of water molecules bound to each barium chloride unit in the crystal lattice.
By heating the barium chloride crystals at 400 degrees Celsius for two hours, the water molecules are driven off, leaving only the anhydrous (water-free) form of barium chloride behind. This anhydrous form is solid and has a lower mass than the hydrated crystals because the water molecules have been removed.
Therefore, after cooling and weighing the barium chloride crystals, the mass is found to be reduced from 30 grams to 20 grams. The lost mass corresponds to the mass of water that was lost during the dehydration process.
In summary, the decrease in mass of the barium chloride crystals is due to the removal of water molecules through the process of dehydration when they were heated in the oven.