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
Eva8 [605]
3 years ago
9

A radioactive isotope has a half-life of 10 minutes.

Chemistry
1 answer:
stellarik [79]3 years ago
4 0

Answer: The time for activity to fell from 800 counts per second to 200 counts per second is 20 minutes

Explanation:

Expression for rate law for first order kinetics is given by:

t=\frac{2.303}{k}\log\frac{a}{a-x}

where,

k = rate constant

t = age of sample

a = let initial amount of the reactant

a - x = amount left after decay process  

a) for finding the rate constant:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

t_{\frac{1}{2}}=\frac{0.693}{k}

k=\frac{0.693}{10min}=0.0693min^{-1}

b) for activity to fell from 800 counts per second to 200 counts per second.

t=\frac{2.303}{0.0693}\log\frac{800}{200}

t=20minutes

The time for activity to fell from 800 counts per second to 200 counts per second is 20 minutes

You might be interested in
What are the smallest sub atomic structure
Anton [14]

Answer:

Electrons

Explanation:

In an atom there would be three subatomic particles: Neutrons, electrons, protons. The smallest and lightest in terms of mass is electrons. This is because the nucleus is comprised of the protons and the neutrons, these have a greater mass than electrons as electrons has very little mass that can considered to be 0.

7 0
3 years ago
Two solutions, initially at 24.60 °C, are mixed in a coffee cup calorimeter (Ccal = 15.5 J/°C). When a 100.0 mL volume of 0.100
yulyashka [42]

Answer:

ΔH = -59.6kJ/mol

Explanation:

The reaction that occurs between Ag⁺ and Cl⁻ ions is:

Ag⁺ + Cl⁻ → AgCl(s) + ΔH

To find ΔH we need to obtain moles of reaction and heat released in the reaction because ΔH is defined as heat released per mole of reaction.

<em>Moles of reaction:</em>

Moles of Ag⁺ and Cl⁻ added are:

Ag⁺: 0.100L * (0.100mol / L) = 0.01moles

Cl⁻: 0.100L * (0.200mol / L) 0 0.02 moles

That means limiting reactant is Ag⁺ and moles of reaction are 0.01 moles

<em>Heat released:</em>

To find heat released we must use coffe cup calorimeter equation:

Q = C*m*ΔT

<em>Where C is specific heat of solution (4.18J/g°C), m is the mass of solution (200g because there are 100 + 100mL = 200mL and density of solution is 1g/mL) and ΔT is change in temperature (25.30°C - 24.60°C = 0.70°C).</em>

Replacing:

Q = C*m*ΔT

Q = 4.18J/g°C * 200g * 0.70°C

Q = 585,2J

Is total heat released.

The calorimeter absorbs:

15.5J / °C * 0.7°C = 10.85

Thus, when 0.01 moles reacts, 585.2J + 10.85  = 596.05J are released (Heat released is heat abosrbed by calorimeter + Heat absorbed by water) and ΔH is:

ΔH = 596.05J / 0.01 moles =

ΔH = 59605J / mol =

<h3>ΔH = -59.6kJ/mol</h3>

<em>As heat is released, ΔH < 0.</em>

6 0
3 years ago
8.5C (H)
Zigmanuir [339]

Answer:

Boron.

Explanation:

5 0
3 years ago
Calcule la molaridad de una solución acuosa de ácido sulfúrico (H₂SO₄) que se preparó al mezclar, en un recipiente aforado, 4 mo
oee [108]

Considerando la definición de molaridad, la molaridad de una solución acuosa de ácido sulfúrico (H₂SO₄) es 0.5 \frac{moles}{litro}.

La molaridad es una medida de la concentración de un soluto en una disolución que se define como el número de moles de soluto que están disueltos en un determinado volumen.

La molaridad de una solución se calcula dividiendo los moles del soluto por el volumen de la solución:

Molaridad=\frac{numero de moles de soluto}{volumen}

La Molaridad se expresa en las unidades \frac{moles}{litro}.

En este caso, sabes que una solución acuosa se preparó al mezclar 4 moles del ácido con suficiente agua hasta completar 8 litros de solución. Entonces, sabes que:

  • número de moles de soluto= 4 moles
  • volumen= 8 litros

Reemplazando en la definición de molaridad:

Molaridad=\frac{4 moles}{8 litros}

Resolviendo:

Molaridad= 0.5 \frac{moles}{litro}

Finalmente, la molaridad de una solución acuosa de ácido sulfúrico (H₂SO₄) es 0.5 \frac{moles}{litro}.

<em>Aprende más</em>:

  • brainly.com/question/17647411?referrer=searchResults
  • brainly.com/question/21276846?referrer=searchResults

8 0
2 years ago
the polio virus is 25 nanometers in diameter. How many would fit across the head of a pin 2 millimeters in diameter
IrinaVladis [17]
2mm=2,000,000 nm
2,000,000/25=80,000
The answer is 80,000 polio viruses
6 0
3 years ago
Read 2 more answers
Other questions:
  • During the summer after your first year at Carnegie Mellon, you are lucky enough to get a job making coffee at Starbucks, but yo
    6·1 answer
  • How many molecules of carbon monoxide (co) are needed to react with excess iron (iii) oxide (fe2o3) to produce 11.6 g of iron (f
    10·1 answer
  • An appliance's energy use over time is called its _____ .
    9·1 answer
  • Choose the more sensible temperature. Cold day: 20 degrees Celsius or -20 degrees Celsius
    8·1 answer
  • You want to place a piece of glass tubing into a ruber stopper after the tubing has been fire polished and cooled. This is best
    6·1 answer
  • After an electric sign is turned on, the temperature of its glass goes from 23.5°C to 65.5°C. The sign’s glass has a mass of 905
    14·2 answers
  • Which type of molecule is shown below?
    7·1 answer
  • The term "cycle" is used in Water Cycle because ?
    5·1 answer
  • PLEASE HELP!!!
    5·2 answers
  • (b) Calculate the temperature of the product mixture if the methane and air are both at an initial temperature of 0.0°C. Assume
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!