Calcium fluoride (CaF2) has a solubility constant of 3.45 x 10-11
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Answer:
Mass of oxygen in glucose = 29.3g
Explanation:
Mass of glucose given is 55grams.
We are to find the mass of oxygen in this compound.
In the compound we have 6 atoms of oxygen.
Solution
To find the mass of oxygen in glucose, we calculate the formula mass of glucose. We now divide the formula mass of the oxygen atom with that of the glucose and multiply by the given mass to find the unkown mass.
Atomic mass of C = 12g
H = 1g
O = 16g
Formula mass of C₆H₁₂O₆ = {(12x6) + (1x12) + (16x6)} = 180
Mass of O in glucose = x 55
= x 55
= 0.53 x 55
Mass of oxygen in glucose = 29.3g
Answer :
The correct answer for primary component of phosphate buffer at pH = 7.4 is H₂PO₄⁻ and HPO₄²⁻ .
<u>Buffer solution :</u>
It is a solution of mixture of weak acid and its conjugate base OR weak base and its conjugate acid . It resist any change in solution when small amount of strong acid or base is added .
<u>Capacity of a good buffer : </u>
A good buffer is identified when pH = pKa .
From Hasselbalch - Henderson equation which is as follows :
If [A⁻] = [HA] ,
pH = pka + log 1
pH = pKa
This determines that if concentration of weak acid and its conjugate base are changed in small quantity , the capacity of buffer to maintain a constant pH is greatest at pka . If the amount of [A⁻] or [HA] is changed in large amount , the log value deviates more than +/- 1M and hence pH .
Hence Buffer has best capacity at pH = pka .
<u>Phosphate Buffer : </u>
Phosphate may have three types of acid-base pairs at different pka ( shown in image ).
Since the question is asking the pH = 7.4
At pH = 7.4 , the best phosphate buffer will have pka near to 7.4 .
If image is checked the acid - base pair " H₂PO₄⁻ and HPO₄²⁻ has pka 7.2 which is near to pH = 7.4 .
Hence we can say , the primary chemical component of phosphate buffer at pH = 7.4 is H₂PO₄⁻ and HPO₄²⁻ .
