Describe a procedure to separate a mixture of sugar, black pepper, and pebbles?
A mixture of black pepper, sugar and pebbles can be separated by sieving with two different sized meshes.
1. First, use a mesh that has a whole size smaller than the pebbles but large enough for the sugar and pepper to pass through (such as a window screen).
2. Add water to the sugar and pepper and stir until the sugar is dissolved (black pepper will mix into the water but not dissolve). Then use a very fine mesh (such as a coffee filter) to separate the black pepper from the sugar solution.
3. Evaporate the water from the sugar solution.
Alternatively, if you did not want to add water to the mix, you could use forced air to separate the sugar and pepper after sieving out the pebbles. The density of pepper is approximately one third that of sugar. So if you were to pour the sugar/pepper mixture from one bowl to another in front of a source of forced air (like a fan), the pepper flakes would be picked up by the wind before the sugar would. You might need to experiment with the fan settings to find the best speed for separation. Also, devise a way to catch the pepper without blowing it all over the room (perhaps use the fan inside a box).
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