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2 years ago

Can you draw the peptide structure at pH 7.0 (including peptide bonds)

Chemistry

1 answer:

ELEN [110]2 years ago

7 0

Answer:

See image below

Explanation:

The image is labeled according to the sequence N'-Trp-Ser-Asg-Gly-Cys-His-COOH' which means that in the main chain of the peptide, the amino group of the Tryptophan and the carboxylic group of the Histidine are free and thus its charge depends on the pH; other groups that rely on the pH are the side groups of the Cysteine and the Histidine.

Overall, ionizable groups in this peptide are:

Amino Group of the Tryptophan (pKa = 9.39)

SH group of the Cysteine (pKa = 8.18)

Secondary amine of the Histidine (pKa = 6.00)

Carboxylic Group of the Histidine (pKa = 1.82)

Then, the amino group of Trp and SH group of Cys are protonated since the peptide is at a pH below the pKa. The secondary amine of the Histidine is deprotonated because the pH is greater than the pKa, as well with its carboxylic acid group.

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Now we need to find the amount of NF3 that can be formed by the complete reactions of each of the reactants. If all of the N2 wa

Alex777 [14]

The question is incomplete, the complete question is:

Nitrogen and fluorine react to form nitrogen fluoride according to the chemical equation:

$N_2(g)+3F_2(g)\rightarrow 2NF_3(g)$

A sample contains 19.3 g of $N_2$ is reacted with 19.3 g of $F_2$ . Now we need to find the amount of $NF_3$ that can be formed by the complete reactions of each of the reactants.

If all of the $N_2$ was used up in the reaction, how many moles of $NF_3$ would be produced?

<u>Answer:</u> 1.378 moles of $NF_3$ are produced in the reaction.

<u>Explanation:</u>

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

Limiting reagent is defined as the reagent which is completely consumed in the reaction and limits the formation of the product.

Excess reagent is defined as the reagent which is left behind after the completion of the reaction.

In the given chemical reaction, $N_2$ is considered as a limiting reagent because it limits the formation of the product and it was completely consumed in the reaction.

We are given:

Mass of $N_2$ = 19.3 g

Molar mass of $N_2$ = 28.02 g/mol

Putting values in equation 1:

$\text{Moles of }N_2=\frac{19.3g}{28.02g/mol}=0.689mol$

For the given chemical reaction:

$N_2(g)+3F_2(g)\rightarrow 2NF_3(g)$

By the stoichiometry of the reaction:

1 mole of $N_2$ produces 2 moles of $NF_3$

So, 0.689 moles of $N_2$ will produce = $\frac{2}{1}\times 0.689=1.378mol$ of $NF_3$

Hence, 1.378 moles of $NF_3$ are produced in the reaction.

8 0

3 years ago

Groundwater in Pherric, New Mexico, initially contains 1.800 mg/L of iron as Fe3+. What must the pH be raised to in order to pre

xenn [34]

Answer : The pH will be, 3.2

Explanation :

As we known that the value of solubility constant of ferric hydroxide at $25^oC$ is, $2.79\times 10^{-39}$

Amount or solubility of iron consumed = (1.800 - 0.3) mg/L = 1.5 mg/L

The given solubility of iron convert from mg/L to mol/L.

$1.5mg/L=\frac{1.5\times 10^{-3}g/L}{56g/mol}=2.7\times 10^{-7}mol/L$

The chemical reaction will be:

$Fe(OH)_3\rightarrow Fe^{3+}+3OH^-$

The expression of solubility constant will be:

$K_{sp}=[Fe^{3+}]\times [3OH^-]^3$

Now put all the given values in this expression, we get the concentration of hydroxide ion.

$2.79\times 10^{-39}=(2.7\times 10^{-7})\times [3OH^-]^3$

$[OH^-]=1.5\times 10^{-11}M$

Now we have to calculate the pOH.

$pOH=-\log [OH^-]$

$pOH=-\log (1.5\times 10^{-11})$

$pOH=10.8$

Now we have to calculate the pH.

$pH+pOH=14\\\\pH=14-pOH\\\\pH=14-10.8\\\\pH=3.2$

Therefore, the pH will be, 3.2

4 0

3 years ago

1. A gas has a volume of 140L at 37 ºC and 620 kpa pressure. Calculate its volume at STP.

solniwko [45]

Answer:

1. Volume as STP = 755 L

2. Outside temperature = 255 K

3. Percentage yield = 70.5%

Explanation:

1. At STP, pressure = 101.3 kpa, temperature = 0°C or 273.15 K

Using the general gas equation :

P1V1/T1 = P2V2/T2

P1 = 620 kpa

V1 = 140 L

T1 = 37°C or (273.15 + 37) K = 310.15 K

P2 = 101.3 kpa

V2 = ?

T2 = 273.15 K

V2 = P1V1T2/P2T1

V2 = 620 × 140 × 273.15 / 101.3 × 310.15

V2 = 755 L

2. Using Charles' gas law:

V1/T1 = V2/T2

V1 = 2.5 L

T1 = 290 K

V2 = 2.2 L

T2 = ?

T2 = V2T1/VI

T2 = 2.2 × 290 / 2.5

T2 = 255 K

3. Equation of reaction : 2 Al + 3 CuSO4 ---> Al2 (SO4)3 + 3 Cu

From equation of the reaction, 2 moles of Al produces 3 moles of Cu

Molar mass of Al = 27 g; Molar mass of Cu = 63.5 g

2 moles of Al = 2 × 27 g = 54 g; 3 moles of Cu = 3× 63.5 = 190.5 g

54 g of Al produces 190.5 g of Cu

1.87 g of Al will produce 190.5/54 × 1.87 g of Cu = 6.60 g of Cu

Percentage yield = actual yield /theoretical yield × 100%

Percentage yield = 4.65/6.60 × 100%

Percentage yield = 70.5%

5 0

2 years ago

A compound is known to consist solely of carbon, hydrogen, and chlorine. Through elemental

OleMash [197]

Answer:

the empirical (lowest raios) is

C2H4Cl

Explanation:

A compound is known to consist solely of carbon, hydrogen, and chlorine. Through elemental analysis, it was determined that the compound is composed of 24.27% carbon.

What is the empirical formula of this compound?

the compound has ONLY C, H, and Cl

the % Cl = 100% - 24.27% -4.03% = 71.7%

in 100 gm, there are 71.7 gm Cl, 24.27 gm C, and 4.03 gm H

the number of moles are Cl=71.7/70.91 =1.01= ~ 1

C = 24.27/12.0 = 2.02 =~ 2

H = 403/1.01 = 3.97 =~ 4

so the empirical (lowest raios) is

C2H4Cl

3 0

2 years ago

Which consequence of global warming is described as having an increase in growing season changes in migration and loss of specie

IgorLugansk [536]

Answer:

Deforestation, increase wildlife extinction, ecosystem imbalances, soil erosion, migration and loss of species.

Explanation:

Global warming is warming the earth's surface temperature, which causes the changes in our ecosystem like deforestation, soil erosion, climate changes, migration and loss of species etc.

Global warming is caused by the 'Greenhouse effect', major gases are carbon dioxide(9-26%), methane(4-9%), water vapour(36-70%) ozone(3-7%) and nitrous oxide.

Global warming affects on the ocean include rising sea level, meiting glaciers, thermal expansion and ice sheets. It also cause the bird migration which carries high cost of predation and mortality.

8 0

3 years ago

Read 2 more answers