Answer:
2.25g of NaF are needed to prepare the buffer of pH = 3.2
Explanation:
The mixture of a weak acid (HF) with its conjugate base (NaF), produce a buffer. To find the pH of a buffer we must use H-H equation:
pH = pKa + log [A-] / [HA]
<em>Where pH is the pH of the buffer that you want = 3.2, pKa is the pKa of HF = 3.17, and [] could be taken as the moles of A-, the conjugate base (NaF) and the weak acid, HA, (HF). </em>
The moles of HF are:
500mL = 0.500L * (0.100mol/L) = 0.0500 moles HF
Replacing:
3.2 = 3.17 + log [A-] / [0.0500moles]
0.03 = log [A-] / [0.0500moles]
1.017152 = [A-] / [0.0500moles]
[A-] = 0.0500mol * 1.017152
[A-] = 0.0536 moles NaF
The mass could be obtained using the molar mass of NaF (41.99g/mol):
0.0536 moles NaF * (41.99g/mol) =
<h3>2.25g of NaF are needed to prepare the buffer of pH = 3.2</h3>
Answer: Europe
Explanation: it’s in germany
Answer:
0.106 mol (3s.f.)
Explanation:
To find the number of moles, divide the mass of glucose (in grams) by its Mr. Glucose has a chemical formula of C6H12O6. To find the Mr, add all the Ar of all the atoms in C6H12O6.
Ar of C= 12, Ar of H= 1, Mr of O= 16
These Ar values can be found on the periodic table.
Mr of glucose= 6(12)+ 12(1) + 6(16)= 180
Moles of glucose
= mass ÷ mr
= 19.1 ÷ 180
= 0.106 mol (3 s.f.)
Answer:
300 kg
Explanation:
The number of people in the city, p = 400,000
The number of capsules of oseltamivir each person consumes per day, n = 2 capsules
The number of days each person consumes the oseltamivir capsules, t = 5 days
The mass of oseltamivir in each capsule, m = 75 mg
The mass of oseltamivir needed to treat all the people in the city, <em>M</em>, is given as follows;
M = n·t·m·p
∴ M (in milligrams) = (2 × 5 × 75 × 400,000) mg = 300,000,000 mg
1,000,000 mg = 1 kg
∴ 300,000,000 mg = 300 kg
The mass of oseltamivir needed to treat all the people in the city, <em>M</em> = 300 kg