1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
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 .

You might be interested in
Explain what makes a covalently bonded molecule polar. Use the molecules of CH4 and CH3F as examples in your explanation.
RideAnS [48]

Answer:

See explanation

Explanation:

The magnitude of electronegativity difference between atoms in a bond determines whether that bond will be polar or not.

If the electronegativity difference between atoms in a bond is about 1.7, the bond is ionic. If the electronegativity difference is greater than 0.4 and less than 1.7, the bond will have a polar covalent character. Lastly, if the electronegativity difference between the bond is less than or equal to 0.4, the covalent bond is non polar.

The electronegativity difference between carbon and hydrogen is about 0.4 which corresponds to a nonpolar covalent bond hence the molecule is nonpolar.

The electronegativity difference between carbon and fluorine is about 1.5 indicating a highly polar bond. This gives CH3F an overall dipole moment thereby making the molecule polar.

8 0
3 years ago
A change in matter that produces one or more new substances is a(n)
lukranit [14]

You could use another word for change can be variable witch means change and if you times the one two more times then you would get four because two time two would be four and times the one would be four.


6 0
3 years ago
Isn’t urgent the first 3 will be marked BRAINIEST
bearhunter [10]

Answer:

Al2(SO4)3 and Mg(OH)2

Explanation:

1. Al has a charge of 3-, and SO4 of 2-

when you cross multiply the charges you get

Al2 and (SO4)3

*the reason theres a bracket around the sulfate ion is that the charge 3 is not for oxygen only, but the entire sulphate ion*

Hence, Al2(SO4)3

2. Mg has a charge of 2- and OH of 1-

again cross multiply

Mg (you dont need to add the 1) and (OH)2

again, the bracket around OH means the charge appiles to Oxygen AND hydrogen

hence, Mg(OH)2

7 0
3 years ago
Read 2 more answers
Will bromine react with sodium and why?
Archy [21]

<span><span>When you write down the electronic configuration of bromine and sodium, you get this

Na:
Br: </span></span>

<span><span />So here we the know the valence electrons for each;</span>

<span><span>Na:  (2e)
Br:  (7e, you don't count for the d orbitals)

Then, once you know this, you can deduce how many bonds each can do and you discover that bromine can do one bond since he has one electron missing in his p orbital, but that weirdly, since the s orbital of sodium is full and thus, should not make any bond.

However, it is possible for sodium to come in an excited state in wich he will have sent one of its electrons on an higher shell to have this valence configuration:</span></span>

<span><span /></span><span><span>

</span>where here now it has two lonely valence electrons, one on the s and the other on the p, so that it can do a total of two bonds.</span><span>That's why bromine and sodium can form </span>

<span>
</span>

4 0
3 years ago
Major Battles of the
san4es73 [151]
Answer: Lexington and Concord

Explanation: The British were trying to find weapons and could not find them.
8 0
3 years ago
Other questions:
  • "how many grams of calcium are consumed when 156.8 ml of oxygen"
    14·1 answer
  • The diagrams below represent the four states of matter.
    6·2 answers
  • According to the periodic table, which two elements are in the same row? A. copper and gold B. sodium and sulfur C. lithium and
    15·1 answer
  • Balance the following redox reaction if it occurs in H2SO4. What are the coefficients in front of C3H8O2 and H2SO4 in the balanc
    15·1 answer
  • Calculate the mass of NaCl needed to make 40% solution from 3kg of water ? Could you explain step by step please :-)
    12·1 answer
  • Why does iron not fit the pattern in column 7
    13·1 answer
  • For potassium metal, the work function ф(the minimum energy needed to eject an electron from the metal surface) is 3.68 x 1019 J
    13·1 answer
  • Which statement best explains the backward motion of the boat as the person moves forward
    11·1 answer
  • Explain the properties of acids
    5·1 answer
  • Please help me if possible<br>​
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!