[harbourfox]

Hey guys any help with answering these questions and maybe some explanation would be greatly appreciated:
1. A first order reaction has a half-life of 1.98 days. The rate constant for the
reaction is
(a) 1.37 days-1
(b) 1972.80 minutes-1
(c) 0.35 days-1
(d) 0.35 mol days

2. The enzyme-catalysed breakdown of drug A (RMM = 470 daltons) to yield
degradation product B (RMM = 235 daltons) is known to follow zero order
kinetics. The concentration of B after 2 hours of reaction is 23.5 mg L-1. The zero
order rate constant is
(a) 11.75 mg L-1 h-1
(b) 47.00 mg L-1 h
(c) 0.05 mM h-1
(d) 0.20 mM h

3. A pharmacist wishes to prepare 200 mL of a solution of 2% %w/v penicillin G
sodium.
a) How much penicillin G sodium will be contained in the formulation?
(Additional information is provided at the end of this question)
 
b) How much sodium chloride is required to render the formulation isotonic?

 c) Glycerin, instead of sodium chloride, is going to be used in this formulation.
How much glycerin should be included?

d) Why is urea not used to adjust the tonicity of pharmaceutical formulations?

e) Why is sodium chloride sometimes not suitable for use as a tonicity adjuster?


The following information may be useful in your calculations; the molecular weight of
penicillin G sodium is 356.4 g/mol. It has an E value of 0.18. It has a V value of 6.0.
It has a ΔTf1% of 0.11. It has a Liso value of 3.8. Glycerin has a molecular weight of
92.09 /mol an E value of 0.34, V value of 11.3, a ΔTf1% of 0.20. It has a Liso value of
1.8.

[billnotgatez]

Please read forrum rules
You need to show some work

[harbourfox]

Please read forrum rules
You need to show some work

I apologise:
1a)This one I really genuinely have no idea.
2. For this one I simply did 23.5/2= 11.75. No idea if that is correct though.
3.a) I thought a %w/v meant the number of grams of substance in the solution of 100mL. So in this case there would be 0.004 x 200= 4g of penicillin G sodium in 200mL?
b) What I did was times amount of substance, 4g, by its E value, 0.18, which gives 0.72. Since an isotonic soln w.r.t. bodily fluids is 0.9g NaCl I subtracted my answer from this, giving 0.18g NaCl needs to be added?
c)I simply took the amount of NaCl neede to be added, 0.18, and divided it by glycerin's E value, 0.34, giving 0.53g.
d) I assume urea is not used as a tonicity adjuster due to its toxic effects as a waste metabolite.
e) I think maybe NaCl can sometimes react with certain drug compounds thus reducing their potency or reducing the drug's stability.
I must say, I am confident on NONE of the above answers so I would appreciate any help/feedback whatsoever. I apologise again for not giving my reasoning to begin with.