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
Anarel [89]
3 years ago
6

Substance A undergoes a first order reaction A  B with a half- life of 20 min at 25 °C. If the initial concentration of A ([A]◦

) in a sample is 2.7 M, what will be the concentration of A after 60 min?
Chemistry
1 answer:
nydimaria [60]3 years ago
6 0

The concentration of A will be <em>0.34 mol·L⁻¹</em> after 60 min.

In a first-order reaction, the formula for the amount remaining after <em>n</em> half-lives is

\text{[A]} = \frac{\text{[A]}_{0}}{2^{n}}\\

If t_{\frac{1}{2}} = \text{20 min}\\

n = \frac{t}{t_{\frac{1}{2}}} = \frac{\text{60 min}}{\text{20 min}}= \text{3.0}

∴ \text{[A]} = \frac{\text{2.7 mol/L}}{2^{3.0}} = \frac{\text{2.7 mol/L}}{8.0} = \textbf{0.34 mol/L}

You might be interested in
PLEASE HELP!!!!! Noble gases are often described as being very stable. Give two points to explain what this means.
Leya [2.2K]

Answer:

Noble Gases are very stable because...

1) Noble Gases have a full octet

2) Low chemical reactivity

Explanation:

This means that is has 8 valence electrons so it won't need any more, so it is less likely to react with other substances.

6 0
3 years ago
What property is primarily responsible for determining the type of electromagnetic energy and peak wavelength emitted by a star
svetoff [14.1K]
The answer i think it is... is Temperature 
Hope this helped!
6 0
3 years ago
Read 2 more answers
Why atomic mass is an average vàlue​
lukranit [14]

Answer:

The atomic mass is the average number of protons and neutrons for all natural isotopes of an element. It is a decimal number.

Explanation:

Atomic Mass and Mass Number Example :

Hydrogen has three natural isotopes: 1H, 2H, and 3H. Each isotope has a different mass number.

1H has 1 proton. Its mass number is 1. 2H has 1 proton and 1 neutron. Its mass number is 2. 3H has 1 proton and 2 neutrons. Its mass number is 3. 99.98% of all hydrogen is 1H 0.018% of all hydrogen is 2H 0.002% of all hydrogen is 3H Together, they give a value of atomic mass of hydrogen equal to 1.0079 g/mol.

4 0
2 years ago
Read 2 more answers
A polonium atom has 84 protons, 124 neutrons, and 84 electrons. What will it change to during alpha decay? A. A lead atom with 8
77julia77 [94]
I think the correct answer would be A. When a polonium atom with 84 protons, 124 neutrons, and 84 electrons undergoes alpha decay, a lead atom would be produced with 82 protons, 122 neutrons, and 84 electrons together with an alpha particle having two protons and two neutrons.
3 0
3 years ago
Read 2 more answers
All of the noble gasses have 8 valence electrons except _____. helium argon xenon neon this is science
pogonyaev
<span>Helium is the noble gas with only 2 valence electrons 

I Hope This helps

</span>
5 0
2 years ago
Read 2 more answers
Other questions:
  • The interior of a refrigerator has a volume of 0.600 m3. the temperature inside the refrigerator in 282 k, and the pressure is 1
    11·1 answer
  • PLEASE HELP ME ILL GIVE YOU A LOT OF POINTS
    9·1 answer
  • Describe an environment that would have a low albedo. Explain where on Earth would you likely find this environment and why. Exp
    5·1 answer
  • What is the limiting reactant and theoretical yield if 0.483 mol of Ti and 0.911 mol Clare used in this reaction: Ti + 2Cl2 → Ti
    15·1 answer
  • How many atoms are in 3.05 grams of copper?
    15·1 answer
  • If one mole of a substance has a mass of 56.0 g, what is the mass of 11 nanomoles of the substance? Express your answer in nanog
    13·1 answer
  • Why do elements in the same group have a similar reactivity?
    9·1 answer
  • How does Gregor Mendel's work with pea plants affect human life today? OA A. People continue to cross pea plants to fix Mendel's
    6·1 answer
  • 3. Calculate the amount of sodium carbonate required to neutralize 50 cc of N-H2SO4.​
    8·1 answer
  • True or false. for all atoms of the same element the 4s orbital is larger than the 3s orbital
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!