1. you need to produce a buffer solution that has a pH of 7.00. you already have
ID: 492941 • Letter: 1
Question
1. you need to produce a buffer solution that has a pH of 7.00. you already have a solution that contains 42.0 mmol of NaH2PO4. how many millimeters of Na2HPO4 will you need to add to this solution m? the pKa of Na2HPO4 I'd 6.86.
2. a buffer is prepared by dissolving 0.250 mol of ethanol acid (HC2H3O2) and 0.100 mol of Na C2H3O2 in water sufficient to yield 1.00 L of solution. (Ka HC2H3O2 is 1.8 × 10 ^-5) what is the pH of the buffer? what is the pH after adding 0.002 mol NaOH?
3. a. suppose 500 mL of a solution containing 8.0 × 10^-3 M Pb+2 is mixed with 500 mL of solution contains 5.0 × 10^-3 MSO4 ^2-. will a precipitate form? (Ksp PbSO4= 6.3×10^-7)
b. will Co (OH)2 (s) form if a 0.020 M solution of Co (NO3)2 is adjusted to pH 9.0? Ksp=2.0x
Explanation / Answer
1)
pH = 7.00
NaH2PO4 mmol = 42.0
Na2HPO4 mmol = ?
pKa = 6.86
pH = pKa + log [Na2HPO4 / NaH2PO4 ]
7.00 = 6.86 + log (Na2HPO4 / 42.0)
log (Na2HPO4 / 42.0) = 0.14
Na2HPO4 mmol = 58.0
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.