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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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A balloon is filled with 0.75 L of Helium gas at 35 °C. If the temperature is increased to 113 °C, what thewill new volume be?
faust18 [17]

Answer: 0.9398 Liters

Explanation:

Charles' Law

V1/ T1 = V2/T2

0.75/35 = ?/113

0.75/35 = 0.9398/113

4 0
3 years ago
Two identical 732.0 L tanks each contain 212.0 g of gas at 293 K, with neon in one tank and nitrogen in the other. Based on the
Vladimir [108]

Answer: (a) Neon, Nitrogen; (b) Neon, Nitrogen; (c) Neon is lower than Nitrogen; (d) It doesn't affect;

Explanation: The kinetic-molecular theory studies the behavior of particles under pre-determinated situation. In cases of gases, the particles moving around colliding with each other and the walls of the container, without loss of energy. In the case in question, all the parameters are the same (same temperature, volume and pressure), except for the gases, which has different molar masses. In this sense, Neon has lower average speed due to its molar mass being higher, which means, its particles moves slower for being heavier. Related to pressure, as velocity is lower, it collides less with the walls of the tank, and so pressure is lower. For density, it doesn't affect the behavior of the system nor the kinetic energy.

7 0
3 years ago
Carbohydrates are made up of carbon, hydrogen, and __________.
Rudik [331]
Oxegan ........
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5 0
3 years ago
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Calculate the mass of a 0.297-mL sample of a liquid with a density of 0.930 g/mL.
tekilochka [14]

Answer: 0.27621 g

Explanation:

0.297 ml *0.930 g/ml=0.27621 g

8 0
2 years ago
The standard cell potential Ec for the reduction of silver ions with elemental copper is 0.46V at 25 degrees celsius. calculate
Cloud [144]

Answer : The \Delta G for this reaction is, -88780 J/mole.

Solution :

The balanced cell reaction will be,  

Cu(s)+2Ag^+(aq)\rightarrow Cu^{2+}(aq)+2Ag(s)

Here, magnesium (Cu) undergoes oxidation by loss of electrons, thus act as anode. silver (Ag) undergoes reduction by gain of electrons and thus act as cathode.

The half oxidation-reduction reaction will be :

Oxidation : Cu\rightarrow Cu^{2+}+2e^-

Reduction : 2Ag^++2e^-\rightarrow 2Ag

Now we have to calculate the Gibbs free energy.

Formula used :

\Delta G^o=-nFE^o

where,

\Delta G^o = Gibbs free energy = ?

n = number of electrons to balance the reaction = 2

F = Faraday constant = 96500 C/mole

E^o = standard e.m.f of cell = 0.46 V

Now put all the given values in this formula, we get the Gibbs free energy.

\Delta G^o=-(2\times 96500\times 0.46)=-88780J/mole

Therefore, the \Delta G for this reaction is, -88780 J/mole.

7 0
3 years ago
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