10. Translate each of the following chemical equations into a sentence.
1 answer:
Answer:
a)
2 moles of Zinc sulphide in solid form reacts with 3 moles of Oxygen in gaseous form to give 2 moles of Zinc oxide in solid form and 2 moles of sulphur dioxide in gaseous form.
b)
1 mole of calcium hydride in solid form reacts with 2 moles of liquid water to give 1 mole of calcium hydroxide dissolved in water and 2 moles of hydrogen in gaseous form.
The chemical reactions are written by writing the chemical formula of the reactants on left side of the arrow followed by chemical formula of the products. The number of atoms of each element must be balanced to follow the law of conservation of mass.
You might be interested in
2KClO₃ → 2KCl + 3O₂
mole ratio of KClO₃ to O₂ is 2 : 3
∴ if moles of O₂ = 5 mol
then moles of KClO₃ =
= 3.33 mol
Mass of KClO₃ needed = mol of KClO₃ × molar mass of KClO₃
= 3.33 mol × ((39 × 1) + (35.5 × 1) + (16 × 3) g/mol
= 407.93 g
mole ratio of KClO₃ to O₂ is 2 : 3
∴ if moles of O₂ = 5 mol
then moles of KClO₃ =
= 3.33 mol
Mass of KClO₃ needed = mol of KClO₃ × molar mass of KClO₃
= 3.33 mol × ((39 × 1) + (35.5 × 1) + (16 × 3) g/mol
= 407.93 g
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⁻ .
