You are a formulation scientist preparing a semisolid topical scream. Your formulation requires that a 1000 mL solvent of pH 7.4 phosphate buffer be prepared to suit the pH of the skin. To prepare the buffer, you must use monobasic sodium phosphate (NaH2PO4) and sodium hydroxide (NaOH) since these two ingredients are compatible with your other ingredients in the cream. NaH2PO4 + NaOH – NA2HP04 + H2O 1. The Ka of NaH2PO4 6.2 x 10-8. Using the Henderson-Hasselbalch equation, calculate the molar ratio of [conjugate base]/[weak acid] that must be used in preparing the buffer. А. 0.39 В. 0.78 C. 1.56 D. 2.34 2. There is an available 50 mL of 0.2M NAH2PO4 in the laboratory. Convert this first to the moles of NaH2PO4. The molar mass of NAH2PO4 is 119.98 g/mol. А. 0.005 mol B. 0.010 mol C. 0.025 mol D. 0.045 mol
You are a formulation scientist preparing a semisolid topical scream. Your formulation requires that a 1000 mL solvent of pH 7.4 phosphate buffer be prepared to suit the pH of the skin. To prepare the buffer, you must use monobasic sodium phosphate (NaH2PO4) and sodium hydroxide (NaOH) since these two ingredients are compatible with your other ingredients in the cream. NaH2PO4 + NaOH – NA2HP04 + H2O 1. The Ka of NaH2PO4 6.2 x 10-8. Using the Henderson-Hasselbalch equation, calculate the molar ratio of [conjugate base]/[weak acid] that must be used in preparing the buffer. А. 0.39 В. 0.78 C. 1.56 D. 2.34 2. There is an available 50 mL of 0.2M NAH2PO4 in the laboratory. Convert this first to the moles of NaH2PO4. The molar mass of NAH2PO4 is 119.98 g/mol. А. 0.005 mol B. 0.010 mol C. 0.025 mol D. 0.045 mol
Chemistry
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ISBN:9781305957404
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Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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2nd question
![You are a formulation scientist preparing a semisolid topical scream. Your formulation requires that a 1000 mL solvent of pH 7.4 phosphate
buffer be prepared to suit the pH of the skin. To prepare the buffer, you must use monobasic sodium phosphate (NAH2PO4) and sodium
hydroxide (NAOH) since these two ingredients are compatible with your other ingredients in the cream.
NaH2PO4 + NаОН — Na2HPО4 + H20
1. The Ka of NaH2PO4 6.2 x 10-8. Using the Henderson-Hasselbalch equation, calculate the molar ratio of [conjugate base]/[weak acid] that
must be used in preparing the buffer.
A.
0.39
В. 0.78
C. 1.56
D. 2.34
2. There is an available 50 mL of 0.2M NAH2PO4 in the laboratory. Convert this first to the moles of NaH2P04. The molar mass of NaH2PO4 is
119.98 g/mol.
A.
0.005 mol B. 0.010 mol
C. 0.025 mol
D. 0.045 mol
3. Given the number of moles of NAH2PO4 available as computed above and the molar ratio calculated, which of the following moles of NaOH
when added to NAH2PO4 will produce the required buffer
А.
0.0061 mol
B. 0.0078 mol
C. 0.0156 mol
D. 0.0390 mol
4. If a readily available 0.2 M NaOH is present in the lab, how many mL of this solution will you use to supply the calculated moles from above?
А.
30.5 mL
B. 39.0 mL
C. 78.0 mL
D. 195.0 mL](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F05dfd1b6-08d3-41c2-80bd-de7c0f166124%2Ff5b96c04-88b2-4357-b57b-b47e962a7a18%2Fv0rrb9_processed.jpeg&w=3840&q=75)
Transcribed Image Text:You are a formulation scientist preparing a semisolid topical scream. Your formulation requires that a 1000 mL solvent of pH 7.4 phosphate
buffer be prepared to suit the pH of the skin. To prepare the buffer, you must use monobasic sodium phosphate (NAH2PO4) and sodium
hydroxide (NAOH) since these two ingredients are compatible with your other ingredients in the cream.
NaH2PO4 + NаОН — Na2HPО4 + H20
1. The Ka of NaH2PO4 6.2 x 10-8. Using the Henderson-Hasselbalch equation, calculate the molar ratio of [conjugate base]/[weak acid] that
must be used in preparing the buffer.
A.
0.39
В. 0.78
C. 1.56
D. 2.34
2. There is an available 50 mL of 0.2M NAH2PO4 in the laboratory. Convert this first to the moles of NaH2P04. The molar mass of NaH2PO4 is
119.98 g/mol.
A.
0.005 mol B. 0.010 mol
C. 0.025 mol
D. 0.045 mol
3. Given the number of moles of NAH2PO4 available as computed above and the molar ratio calculated, which of the following moles of NaOH
when added to NAH2PO4 will produce the required buffer
А.
0.0061 mol
B. 0.0078 mol
C. 0.0156 mol
D. 0.0390 mol
4. If a readily available 0.2 M NaOH is present in the lab, how many mL of this solution will you use to supply the calculated moles from above?
А.
30.5 mL
B. 39.0 mL
C. 78.0 mL
D. 195.0 mL
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