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Ad libitum [116K]
3 years ago
8

A certain drug has a half-life in the body of 4.0h. What should the interval between doses be, if the concentration of drug in t

he body should not fall below 15.% of its initial concentration? Round your answer to 2 significant digits.
Chemistry
1 answer:
scZoUnD [109]3 years ago
8 0

Answer:

Explanation:

half life = 4 h

initial concentration = 100

final concentration = 15

Time = t

No of half life  x = t / 4

15 = 100 x ( 1/2 )ˣ

.15 =  ( 1/2 )ˣ

ln .15 = - x ln2

x = - ln .15 / ln 2

= 1.897 / .693

x = 2.737

x = t / 4

t = 2.737 x 4 = 11 h approx .

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When you take 10 grams of salt, and dissolve it in 25 grams of hot water what is the solubility
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2 years ago
what volume of a 0.149 m potassium hydroxide solution is required to neutralize 17.0 ml of a 0.112 m hydrobromic acid solution?
IgorLugansk [536]

Answer: 12.78ml

Explanation:

Given that:

Volume of KOH Vb = ?

Concentration of KOH Cb = 0.149 m

Volume of HBr Va = 17.0 ml

Concentration of HBr Ca = 0.112 m

The equation is as follows

HBr(aq) + KOH(aq) --> KBr(aq) + H2O(l)

and the mole ratio of HBr to KOH is 1:1 (Na, Number of moles of HBr is 1; while Nb, number of moles of KOH is 1)

Then, to get the volume of a 0.149 m potassium hydroxide solution Vb, apply the formula (Ca x Va)/(Cb x Vb) = Na/Nb

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cross multiply

1.904 x 1 = 0.149Vb x 1

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Thus, 12.78 ml of potassium hydroxide solution is required.

5 0
3 years ago
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