Answer:
67.6 years is the time the isotope take to decay from 0.900g to 0.170g
Explanation:
The radioactive decay follows first order law:
Ln [A] = -kt + ln[A]₀
Where [A] is concentration after time t,
k is decay constant:
k = ln 2 / t(1/2)
k = ln2 / 28.1 years
k = 0.02467 years⁻¹
[A]₀ = Initial concentration.
We can replace concentration and use the mass of the isotope:
Ln [A] = -kt + ln[A]₀
Ln [0.170g] = -0.02467 years⁻¹t + ln[0.900g]
-1.667 = -0.02467 years⁻¹t
t =
67.6 years is the time the isotope take to decay from 0.900g to 0.170gThe time required for the sample to reduce to 0.170 grams has been 67.75 years.
Half-life can be defined as the times required by the substance to reduce to half of its initial concentration.
The half-life can be expressed as:
Amount left = Initial amount [tex]\times[/tex] [tex]\rm \dfrac{1}{2}^\dfrac{time}{Half-life}[/tex]
From the given:
0.17 g = 0.9 [tex]\rm \times\;\dfrac{1}{2}^\dfrac{t}{28.1}[/tex]
[tex]\rm \dfrac{0.17}{0.9}[/tex] = [tex]\rm \dfrac{1}{2}^\dfrac{t}{28.1}[/tex]
0.188 = [tex]\rm (0.5)^\dfrac{t}{28.1}[/tex]
Taking log on both the sides,
log 0.188 = [tex]\rm \dfrac{t}{28.1}\;\times[/tex] log 0.5
2.411 = [tex]\rm\dfrac{t}{28.1}[/tex]
t = 2.411 [tex]\times[/tex] 28.1 years
Time = 67.75 years.
The time required for the sample to reduce to 0.170 grams has been 67.75 years.
For more information about half-life, refer to the link:
https://brainly.com/question/24710827
Do all irreversible reactions go to completion? If so why?
Answer:
True
Explanation:
All irreversible reactions go to completion because the process cannot proceed in the backward direction.
A reversible reaction is one that does not go into completion in one direction.
An irreversible direction completely uses up the reactants to form the products and goes into completion.
These reactions can only proceed in one direction and not both.
Group 17 is called the halogen family, and the group to its right is called the noble gases. How are these elements alike and how are they different?
Explanation:
The halogen family and noble gases are similar in just one particular way, they are groups of non-metals. All members of these two groups are categorized as non-metals.
Here are some of the differences between them;
Halogens have 7 electrons in their outermost shell whereas noble gases have 8 electrons in theirs. Halogens are highly reactive elements, noble gases are non-reactive. Halogens are made up of electronegative elements where as noble gases are neither electropositive nor electronegative.Please give formulas of how you solved I only need help on a but if you can do all that I would appreciate that.
Answer:
3.1 moles of ammonia
18.67× 10²³ molecules
Mass = 52.7 g
Explanation:
Given data:
Number of atoms of hydrogen = 5.68×10²⁴ atoms
A) Number of molecules of ammonia = ?
Solution:
First of all we will calculate the number of moles of hydrogen.
1 mole = 6.022× 10²³ atoms
5.68×10²⁴ atoms × 1 mol / 6.022× 10²³ atoms
0.94×10¹ mol
9.4 moles of hydrogen
Moles of ammonia:
3 moles of hydrogen are present in one mole of ammonia.
9.4 moles of hydrogen = 1/3×9.4 =
3.1 moles of ammonia
Number of molecules of ammonia:
1 mole contain 6.022× 10²³ molecules.
3.1 mol × 6.022× 10²³ molecules / 1 mol
18.67× 10²³ molecules
c) Mass of sample = ?
Mass = number of moles × molar mass
Mass = 3.1 moles × 17 g/mol
Mass = 52.7 g
Is buoyancy a physical or chemical property?
which of the following would form an ionic bond?
a.strontium and oxygen
b. sulfur and oxygen