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3 years ago

Compare the mass of a proton to the mass of an electron.

1 answer:

5 0

Electrons are only about 0.054% as massive as neutrons and protons are only 99.86% as massive as the neutrons. The mass of the Proton is 1.67 x 10^-27 kg and the mass of the electron is 9.11 x 10^-31 kg. The mass of the electron is so much lighter than the mass of the proton.

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Draw the product that valine forms when it reacts with excess CH3CH2OH and HCl followed by a wash with aqueous base.

-BARSIC- [3]

Answer:

Product: ethyl L-valinate

Explanation:

If we want to understand what it is the molecule produced we have to analyze the reagents. We have valine an amino acid, in this kind of compounds we have an amine group ( $NH_2$ ) and a carboxylic acid group ( $COOH$ ). Additionally, we have an alcohol ( $CH_3CH_2OH$ ) in the presence of HCl (a strong acid) in the first step, and a base ( $OH^-$ ).

When we have an acid and an alcohol in a vessel we will have an esterification reaction. In other words, an ester is produced. As the first step, the oxygen in the C=O (in the carboxylic acid group) would be protonated. In the second step, the ethanol attacks the carbon in the C=O of the carboxylic acid group producing a new bond between the oxygen in the ethanol and the carbon in the carboxylic acid. In step 3, a proton is transferred to produce a better leaving group ( $H_2O$ ). In step 4, a water molecule leaves the main structure to produce again the double bond C=O. Finally, a base ( $OH^-$ ) removes the hydrogen from the C=O bond to produce ethyl L-valinate

See figure 1

I hope it helps!

7 0

3 years ago

A gas has a volume of 240 mL and a pressure of 0.99 atm. If the pressure is decreased to 0.951 atm, what is the new volume of th

irakobra [83]

V2 = 250 ml

Explanation:

Given:

P1 = 0.99 atm. V1 = 240 ml

P2 = 0.951 atm. V2 = ?

We can use Boyle's law to solve for V2

P1V1 = P2V2

V2 = (P1/P2)V1

= (0.99 atm/0.951 atm)(240 ml)

= 250. ml

6 0

2 years ago

Plot the data points on the graph below and use the corresponding dot colors: 1st data point - blue, 2nd data point - yellow, 3r

yulyashka [42]

Answer:

The answer is an attached file

Explanation:

I hope it'll be useful to you.

4 0

2 years ago

Read 2 more answers

The painkiller, Advil® contains the active ingredient ibuprofen (IB), which has a pKb of

denis23 [38]

This problem is providing the basic dissociation constant of ibuprofen (IB) as 5.20, its pH as 8.20 and is requiring the equilibrium concentration of the aforementioned drug by giving the chemical equation at equilibrium it takes place. The obtained result turned out to be D) 4.0 × 10−7 M, according to the following work:

First of all, we set up an equilibrium expression for the given chemical equation at equilibrium, in which water is omitted for it is liquid and just aqueous species are allowed to be included:

$Kb=\frac{[IBH^+][OH^-]}{[IB]}$

Next, we calculate the concentration of hydroxide ions and the Kb due to the fact that both the pH and pKb were given:

$pOH=14-8.20=5.80$

$[OH^-]=10^{-5.8}=1.585x10^{-6}M$

$Kb=10^{-5.20}=6.31x10^{-6}$

Then, since the concentration of these ions equal that of the conjugated acid of the ibuprofen (IBH⁺), we can plug in these and the Kb to obtain:

$6.31x10^{-6}=\frac{(1.585x10^{-6})(1.585x10^{-6})}{[IB]}$