How and why do we see colors?

Chemistry

1 answer:

vladimir1956 [14]2 years ago

7 0

Answer:

Light receptors within the eye transmit messages to the brain, which produces the familiar sensations of color. Newton observed that color is not inherent in objects. Rather, the surface of an object reflects some colors and absorbs all the others. We perceive only the reflected colors.

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How many molecules of water are released during the polymerization of a 20 monomer-long cellulose molecule?

Alborosie

Answer:

During the polymerization of a 20 monomer-long cellulose molecule, 19 molecules of water are released.

Explanation:

In simple terms, cellulose is the biopolymer formed by many glucose units. This is cellulose is the polymer and glucose is the monomer.

To have a 20 monomer-long cellulose molecule, 20 monomers have been chemically bonded by reacting 19 times, as it is explained in the next paragrpahs, and so 19 molecules of water have been released.

You can imaging the polymerization process as a step-by-step reaction in which the first step is the condensation reaction of one glucose molelecule to produce a 2 monomer-long chain, with the release of one molecule of water: the second step would be the condensation reaction between the 2 monomer-long chain with another glucose molecule, with the release of an additional molecule of water, and so on, until 19 condensation reactions happen, to obtain the 20 monomer-long cellulose molecule.

Condensation is the loss of water in a chemical reaction.

When two glucose molecules react together, condensation occurs. One OH group from each glucose molecule come together, the OH from one glucose molecule combines with the H part of the OH from the other glucose molecule, to form H₂O (water that is released).

The two glucose molecules (monomers) will form one bigger molecule where the two glucose monomers are bonded through the oxygen atom that did not form part of the water molecule released.

Then, a 20-monomer chain means 19 condenstation reactions, with the release of 19 molecules of water.

8 0

3 years ago

A hydrate is compound that included water molecules within its crystal structure. During an experiment to determine the percent

stellarik [79]

Answer:

The percent by mass of water in this crystal is:

21.4%

Explanation:

This exercise can be easily solved using a simple rule of three where the initial weight of the hydrated crystal (6,235 g) is taken into account as 100% of the mass, and the percentage to which the mass of 4.90 g corresponds (after getting warm). First, the values and unknown variable are established:

6,235 g = 100%
4.90 g = X

And the value of the variable X is found:

X = (4.90 g * 100%) / 6,235 g
X = approximately 78.6%.

The calculated value is not yet the percentage of the water, since the water after heating the glass has evaporated, therefore, the remaining percentage must be taken, which can be calculated by subtraction: