Answer:
Kw = 2.88 × 10⁻¹⁵
Explanation:
Let's consider the dissociation of water.
H₂O(l) ⇄ H⁺(aq) + OH⁻(aq)
The equilibrium constant Kw is:
Kw = [H⁺].[OH⁻]
If pH = 7.27, we can find [H⁺]:
pH = -log [H⁺]
H⁺ = anti log (-pH) = anti log (-7.27) = 5.37 × 10⁻⁸ M
According to the balanced equation, 1 mole of H⁺ is produced per mole of OH⁻. So, [H⁺] = [OH⁻] = 5.37 × 10⁻⁸ M
Then,
Kw = [H⁺].[OH⁻]= (5.37 × 10⁻⁸)² = 2.88 × 10⁻¹⁵
Answer:
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
∈ = Molar extinction co-efficient
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.
Answer:
a. Plum pudding model
Explanation:
The plum pudding model of the atom was proposed by J.J. Thomson. It was the model he derived from his experiment on the gas discharge tube.
J.J Thomson was the first person to discover electrons which he called cathode rays because in the discharge tube, they emanate from the cathode.
- This led him to suggest the plum pudding model of the atom.
- The model reflects electrons being surrounded by a volume of negative charges.
Find your answer in the explanation below.
Explanation:
PV = nRT is called the ideal gas equation and its a combination of 3 laws; Charles' law, Boyle's law and Avogadro's law.
According to Boyle's law, at constant temperature, the volume of a gas is inversely proportional to the pressure. i.e V = 1/P
From, Charles' law, we have that volume is directly proportional to the absolute temperature of the gas at constant pressure. i.e V = T
Avogadro's law finally states that equal volume of all gases at the same temperature and pressure contain the same number of molecules. i.e V = n
Combining the 3 Laws together i.e equating volume in all 3 laws, we have
V = nT/P,
V = constant nT/P
(constant = general gas constant = R)
V = RnT/P
by bringing P to the LHS, we have,
PV = nRT.
Q.E.D
Atoms are fundamental constituents of all matter. The following statement is correct. The nucleus always has a positive charge. This is because the nucleus contains sub-atomic particles called protons. Each proton carries a single positive charge. The nucleus is also home to sub-atomic particles called neutrons that do not possess a charge.
