Answer:
(A) pH < 1 the predominant form is the cation: H3C-C(H)(NH3+)-COOH
(B) pH = pl the predominant form is the zwitterion H3C-C(H)(NH3+)-COO-
(C) pH > 11 the predominant form is the anion: H3C-C(H)(NH2)-COO-
(D) Does not occurs in any significant pH: H3C-C(H)(NH2)-COOH
Explanation:
Amino acids are bifunctional because they have an amine group and a carboxyl group. The amine group is a weak base and the carboxyl group is a weak acid, but the pKa of both groups will depend on the whole structure of the amino acid. Also, every amino acid has an isoelectric point (pI), which means the pH were the predominant form of the amino acid is the zwitterion. The structure of the alanine (CH3CH2NH2COOH) shows it has the carboxyl group at C1 with a pKa1 of 2.3 and the amino group at C2 whit the pKa2 of 9.7. The isoelectric poin (pI) of Alanine is 6. Consequently, the protonation of the molecule will depend on the pH of the solution. There are three possibilities:
1) If the pH is under the pKa of the carboxyl group (2.3) the predominant form will be with the amino group protonated, forming a cation (CH3CH(NH3+)COOH).
2) If the pH is between pKa1 (2.3) and pKa2 (9.7) the predominant form will be the zwitterion (CH3CH(NH3+)(COO-)).
3) If the pH is upper the pKa2 of the amino group (9.7) the predominant form will be with the carboxyl group deprotonated, forming an anion (CH3CHNH2(COO-)).
Answer : The correct option is, 30 protons
Explanation :
Element = Zinc
Atomic number = 30
Atomic mass number = 65
As we know that the atomic number is equal to the number of electrons and number of protons.
Atomic number = Number of electrons = Number of protons = 30
Number of neutrons = Atomic mass - Number of protons = 65 - 30 = 35
Therefore, the number of protons an uncharged zinc atom have 30 protons.
Remember the formula as per the second Law of Newton: F = m*a
And also remember that the weight is the force with which the mass is attracted by the planet (or satellite in the case of the moon).
With that information you can answer the questions:
a) Weight = F = m*a
m = 175 slugs = 175 lbm
i) Earth
a = 32.17 ft/s^2
Weight on Earth = 175 lbm * 32.17 ft / s^2 = 5,629.75 poundal
ii) Moon
a = [1/6] 32.17 ft/s^2
Weight on the Moon = [1/6]*5,629.75 poundal = 938.29 poundal
b) Force = 355 poundal
m = 25.0 slug
a in m/s^2 = ?
First calculate the force in ft/s^2
F = m*a => a = F/m = 355 poundal / 25.0 slug = 14.2 ft/s^2
Conversion:
14.2 ft / s^2 * [ 0.3048 m/ft] = 4.32816 m/s^2
Answer: 4.33 m/s^2
The simplified solubility of glucose at 30°C is 1.25 g/g of water. Considering that the density of water at 30°C is 1 g/mL, the equivalent mass of 400 mL of water is also 400g.
The concentration of the solution in water is,
550 g/400g of water = 1.375 g glucose / g of water
Since the concentration is higher compared to the solubility of glucose at the specified temperature, it can be said that the solution is SATURATED.
