One of the best buffer choice for pH = 8.0 is Tris with Ka value of 6.3 x 10^-9.
To support this answer, we first calculate for the pKa value as the negative logarithm of the Ka value:
pKa = -log Ka
For Tris, which is an abbreviation for 2-Amino-2-hydroxymethyl-propane-1,3 -diol and has a Ka value of 6.3 x 10^-9, the pKa is
pKa = -log Ka
= -log (6.3x10^-9)
= 8.2
We know that buffers work best when pH is equal to pKa:
pKa = 8.2 = pH
Therefore Tris would be a best buffer at pH = 8.0.
Answer:
Height = 1.9493 cm
Width = 1.9493 cm
Depth = 1.9493 cm
Solution:
Data Given:
Mass = 20 g
Density = 2.7 g/mL
Step 1: Calculate the Volume,
As,
Density = Mass ÷ Volume
Or,
Volume = Mass ÷ Density
Putting values,
Volume = 20 g ÷ 2.7 g/mL
Volume = 7.407 mL or 7.407 cm³
Step 2: Calculate Dimensions of the Cube:
As we know,
Volume = length × width × depth
So, we will take the cube root of 7.407 cm³ which is 1.9493 cm.
Hence,
Volume = 1.9493 cm × 1.9493 cm × 1.9493 cm
Volume = 7.407 cm³
Answer:
(B) II, IV.
hope this answer is helpful for u.
