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
Nikolay [14]
3 years ago
7

the half life of a certain element is 100 days. how many half-lives will it be before only one-fourth of this element reamains

Chemistry
1 answer:
Rama09 [41]3 years ago
4 0

Answer:

200 Days

Explanation:

Usually not so good in chemistry, but this is math!

Half life means in this time half goes away.  What happens when two half lives pass?  half of what was remaining goes away.  Maybe an example will make it more clear.

Say we start with 100 grams.  After the amount of time for the half life to pass completes, we have 50, or half of the original amount.  The half life time passes again and THAT gets cut in half to 25 grams.  this is 1/4 of the original (Hey, what we're looking for.)  Just to make it clear what is happening after another half life 1/8 remains, so it goes from The starting amount to 1/2 to 1/4 to 1/8 and so on, it keeps getting cut in half.

So how many times do we have to cut 1 in half until we get to 1/4?  Twice as was shown before.  Now, two half lives for this element is what?  100+100 days.  So 200 Days.

You might be interested in
Balance this equation Hgo —> Hg + O2
Nesterboy [21]

Answer:

2Hgo —>2Hg + O2

Explanation:

6 0
2 years ago
Heat Transfer Lab
scoray [572]

Heat Transfer Lab

The following represents a lab set up for heat transfer. The cup on the left started with boiling water at 100 degrees C and the cup on the right has water at 20 degrees C. There is an aluminum bar between the two cups allowing heat to transfer from one cup into the other. The set up will be left alone for 20 minutes and temperatures of each cup of water will be recorded every minute for 20 minutes.

mag-aral ka

5 0
2 years ago
If 20.0 g of NaOH is added to 0.750 L of 1.00 M Cd(NO₃)₂, how many grams of Cd(OH)₂ will be formed in the following precipitatio
bulgar [2K]

Answer:

m_{Cd(OH)_2}=36.6 gCd(OH)_2

Explanation:

Hello.

In this case, for the given chemical reaction, in order to compute the grams of cadmium hydroxide that would be yielded, we must first identify the limiting reactant by computing the yielded moles of that same product, by 20.0 grams of NaOH (molar mass = 40 g/mol) and by 0.750 L of the 1.00-M solution of cadmium nitrate as shown below considering the 1:2:1 mole ratios respectively:

n_{Cd(OH)_2}^{by\ NaOH}=20.0gNaOH*\frac{1molNaOH}{40gNaOH} *\frac{1molCd(OH)_2}{2molNaOH} =0.25molCd(OH)_2\\\\n_{Cd(OH)_2}^{by\ Cd(NO_3)_2}=0.750L*1.00\frac{molCd(NO_3)_2}{L}*\frac{1molCd(OH)_2}{1molCd(NO_3)_2}  =0.75molCd(OH)_2

Thus, since 20.0 grams of NaOH yielded less of moles of cadmium hydroxide, NaOH is the limiting reactant, therefore the mass of cadmium hydroxide (molar mass = 146.4 g/mol) is:

m_{Cd(OH)_2}=0.25molCd(OH)_2*\frac{146.4gCd(OH)_2}{1molCd(OH)_2} \\\\m_{Cd(OH)_2}=36.6 gCd(OH)_2

Best regards.

4 0
2 years ago
A 1.0 mole sample of fluorine gas at 25 °C has an average molecular velocity of 415 m/s. What is the total KE of the gas sample?
Mariana [72]

The total kinetic energy of the gas sample is 3.3 KJ

<h3>What is kinetic energy? </h3>

This is the energy possessed by an object in motion. Mathematically, it can be expressed as:

KE = ½mv²

Where

  • KE is the kinetic energy
  • m is the mass
  • v is the velocity

<h3>How to determine the mass of the fluorine gas</h3>
  • Molar mass of fluorine gas = 38 g/mol
  • Mole of fluorine gas = 1 mole
  • Mass of fluorine gas = ?

Mass = mole × molar mass

Mass of fluorine gas = 1 × 38

Mass of fluorine gas = 38 g

<h3>How to determine the KE of the gas sample</h3>
  • Mass (m) = 38 g = 38 / 1000 = 0.038 Kg
  • Velocity (v) = 415 m/s
  • Kinetic energy (KE) =?

KE = ½mv²

KE = ½ × 0.038 × 415²

KE = 3272.275 J

Divide by 1000 to express in kilojoule

KE = 3272.275 / 1000

KE = 3.3 KJ

Learn more about energy:

brainly.com/question/10703928

#SPJ1

4 0
1 year ago
Out of the 3 of these
Delvig [45]
Electrons can be transformed from on object to another , (can you mark me brainlyest)
6 0
2 years ago
Other questions:
  • What is the mass (in grams) of 9.79 × 1024 molecules of methanol (CH3OH)?
    10·1 answer
  • Which is caused by gravity?
    9·1 answer
  • List 5 careers in computer Science
    7·1 answer
  • The values between 1 and 14. The formula for pH is y = − log 10 ⁡ x, where y is the pH value and x is the concentration of hydro
    9·1 answer
  • 2. Calculate the density of a liquid in a beaker. The beaker has a mass of 15 grams when empty. The beaker plus an unknown liqui
    10·2 answers
  • an object with a mass of 7.6 G raises the level of water in a graduated cylinder from 25.1 ml to 30.8 ml what is the density of
    5·1 answer
  • Which of the following is another term for eruptions of gas on the sun's surface?
    9·1 answer
  • Somebody help me asap please giving brainliest
    7·1 answer
  • Energy and cemical reaction short answer <br>​
    15·1 answer
  • Give 1 example of a chemical reaction that is involved in coral<br> bleaching.
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!