Question

In: Chemistry

Describe the changes in color and state of matter that occurred when the iodine is heated....

Describe the changes in color and state of matter that occurred when the iodine is heated.

Compare the color of crystals on the evaporating dish bottom with those in the iodine reagent bottle.

Compare the colors of the two cyclohexane solutions after the samples were added.

What is the identity of the deposited substance on the bottom of the evaporating dish? Explain your reasoning.

What pieces of evidence demonstrated that physical changes occurred? Explain your reasoning in a logical, scientific manner based on the experimental evidence.

Compare the original copper metal with the material obtained after heating the copper.

Compare the color of the liquid obtained after putting the unheated copper in the sulfuric acid to the color of the liquid obtained after putting the heated copper (black material) in the sulfuric acid. In other words, compare the color of the liquids in the two test tubes.

Do copper and the black material (copper(II) oxide) have the same physical and chemical properties? Explain your reasoning.

Expert Solution

Describe the changes in color and state of matter that occurred when the iodine is heated.

Answer: Iodine is a sublimating element which means it goes to gaseous state directly from the solid state. The color changes from dark brown to violet. Up on cooling the iodine vapors condensed as crystals.

Compare the color of crystals on the evaporating dish bottom with those in the iodine reagent bottle.

Answer: The color of the crystals is shiny purple and in the reagent bottle it is brown.

Compare the colors of the two cyclohexane solutions after the samples were added.

Answer: The crystals will give bright violet color and the iodine from reagent bottle will give purple-brown color when dissolved in cyclohexane.

What is the identity of the deposited substance on the bottom of the evaporating dish?

Answer: Sublimation is a physical transformation of matter from one state to another. As there was no chemical reaction taken place, the substance remained the same, Iodine.

What pieces of evidence demonstrated that physical changes occurred?

Answer: After sublimation, Iodine becomes more pure, crystallized and gives different colors in solution. The matter moved from the bottom of the beaker and deposited underneath of the evaporating dish after condensation in contact of the surface with low temperature. So, solid to gas to again solid demonstrate the physical change.

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