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:
3.
D. Philippine Atmospheric, Geophysical and Astronomical Services
Administration (PAGASA)
Explanation:
4.C. 62.0 kph
In a endothermic reaction energy from an outside source is continuously being added.
Photosynthesis. Because the plants give off oxygen as a waste product. Carbon dioxide then moves from the air into the leaves of plants through tiny openings in the plants leaves.
Answer:
MOLARITY= 0.3092mol/l
ABSOLUTE UNCERTAINTY= 0.000873
Explanation:
The equation of reaction is
2HNO3 + Na2CO3 ⟶ 2NaNO3 + H2O + CO2.
QUESTION1: CALCULATION FOR MOLARITY;
Molarity= gram mole of solute ÷ liters of solution
Where;
Mole of solute= mass ÷ molar mass
Therefore;
Mole of solute= 0.8311g ÷ 105.988g/mol= 0.0078515mol
MOLARITY= 0.0078415mol ÷ 25.36ml = 0.0003092mol/ml = 0.3092mol/l
This is the Molarity of the solution
QUESTION2: CALCULATION FOR ABSOLUTE UNCERTAINTY;
Uncertainty (u) =√([0.05 ÷ 25.36]^2 + [0.001 ÷ 105.988]^2 + [0.0007 ÷ 0.8311]^2) × Molarity
Solving brackets gives
(0.00197161+0.00000943503+0.00084226) ×Molarity
Adding up gives
0.002823×Molarity
Therefore;
ABSOLUTE UNCERTAINTY= 0.002823×0.3092= 0.000873
