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aniked [119]
3 years ago
15

A flashlight battery is hooked to a toy motor, and then the battery and the connections are sprayed with a water-proof coating.

The battery is immersed in a beaker holding 100 mL of water. When the toy motor drives a device that raises a weight of 1.00 kg a distance of 10.0 m, the temperature of the water falls by 0.024 C. Assuming that the heat capacity of the battery is negligible compared to that of the water, Calculate the change in the energy of the battery contents as a result of the chemical reaction that took place in the battery.
Chemistry
1 answer:
denis-greek [22]3 years ago
4 0

Explanation:

Formula to calculate work done by motor is as follows.

         Work done by motor = mass \times g \times height

where,   g = gravitational constant = 10 m/s^{2}

Therefore, work done by motor is as follows.

 Work done by motor = 1.00 kg \times 10 m/s^{2} \times 10.0 m  

                                  = 100.0 J

Now, heat lost by water will be calculated as follows.

            q = mC \times \Delta T

                = g \times 4.184 J/g^{o}C \times 0.024^{o}C

                = 10.0 J

Hence, heat gained by motor = heat lost by water

As, heat gained by motor = 10.0 J

So, change in energy = heat gained - work done

Therefore, change in energy will be calculated as follows.  

   Change in energy = heat gained - work done

                                  = (10.0 J) - (100.0 J)

                                   = -90.0 J

Thus, we can conclude that change in the energy of the battery contents is -90.0 J.

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How many pairs are shared between the nitrogen atoms for hydrazine
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which of the following amino acids are used to measure the protein concentration by UV? A. His B. Pro C. Trp D. Phe E. Tyr
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C. Trp D. Phe E. Tyr

Explanation:

The concentration of a protein has a direct relation with absorbance of the protein in a UV spectrophotometer. The formula which relates concentration with absorbance is described as under:

                A = ∈ x c x l

where, A = Absorbance

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            c  = Concentration of absorbing species i.e. protein

             l  = Path length of light

       

Tryptophan (Trp), phenylalanine (Phe ) and tyrosine (Tyr) are three aromatic amino acids which are used to measure protein concentration by UV. It is mainly because of tryptophan (Trp), protein absorbs at 280 nm which gives us an idea of protein concentration during UV spectroscopy.

The table depicting the wavelength at which these amino acids absorb and their respective molar extinction coefficient is as under:

Amino acid                Wavelength            Molar extinction co-efficient (∈)

Tryptophan                     282 nm                        5690

Tyrosine                          274 nm                        1280

Phenylalanine                 257 nm                        570

In view of table above, we can easily see that Molar extinction co-efficient (∈) of Tryptophan is highest amongst all these 3 amino acids that is why it dominates while measuring concentration.

7 0
3 years ago
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Answer:

See figure 1

Explanation:

On this case we have a <u>base</u> (methylamine) and an <u>acid</u> (2-methyl propanoic acid). When we have an acid and a base an <u>acid-base reaction </u>will take place, on this specific case we will produce an <u>ammonium carboxylate salt.</u>

Now the question is: <u>¿These compounds can react by a nucleophile acyl substitution reaction?</u> in other words <u>¿These compounds can produce an amide? </u>

Due to the nature of the compounds (base and acid), <u>the nucleophile</u> (methylamine) <u>doesn't have the ability to attack the carbon</u> of the carbonyl group due to his basicity. The methylamine will react with the acid-<u>producing a positive charge</u> on the nitrogen and with this charge, the methylamine <u>loses all his nucleophilicity.</u>

I hope it helps!

5 0
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