Use the concepts in this chapter to obtain an estimate for the number of atoms in the universe. Make the following assumptions: (a) All of the atoms in the universe are hydrogen atoms in stars. (This is not a ridiculous assumption because over three-fourths of the atoms in the universe are in fact hydrogen. Gas and dust between the stars represent only about 15% of the visible matter of our galaxy, and planets compose a far smaller fraction.) (b) The sun is a typical star composed of pure hydrogen with a density of 1.4 g/cm 3 and a radius of 7 x 10 8 m. (c) Each of the roughly 100 billion stars in the Milky Way galaxy contains the same number of atoms as our sun. (d) Each of the 10 billion galaxies in the visible universe contains the same number of atoms as our Milky Way galaxy.
Use the concepts in this chapter to obtain an estimate for the number of atoms in the universe. Make the following assumptions: (a) All of the atoms in the universe are hydrogen atoms in stars. (This is not a ridiculous assumption because over three-fourths of the atoms in the universe are in fact hydrogen. Gas and dust between the stars represent only about 15% of the visible matter of our galaxy, and planets compose a far smaller fraction.) (b) The sun is a typical star composed of pure hydrogen with a density of 1.4 g/cm 3 and a radius of 7 x 10 8 m. (c) Each of the roughly 100 billion stars in the Milky Way galaxy contains the same number of atoms as our sun. (d) Each of the 10 billion galaxies in the visible universe contains the same number of atoms as our Milky Way galaxy.
Solution Summary: The author explains how to determine the number of atoms in the universe based on the given assumptions.
Use the concepts in this chapter to obtain an estimate for the number of atoms in the universe. Make the following assumptions: (a) All of the atoms in the universe are hydrogen atoms in stars. (This is not a ridiculous assumption because over three-fourths of the atoms in the universe are in fact hydrogen. Gas and dust between the stars represent only about 15% of the visible matter of our galaxy, and planets compose a far smaller fraction.) (b) The sun is a typical star composed of pure hydrogen with a density of 1.4 g/cm3 and a radius of 7 x 108m. (c) Each of the roughly 100 billion stars in the Milky Way galaxy contains the same number of atoms as our sun. (d) Each of the 10 billion galaxies in the visible universe contains the same number of atoms as our Milky Way galaxy.
Using reaction free energy to predict equilibrium composition
Consider the following equilibrium:
2NH3 (g) = N2 (g) +3H₂
—N2 (g) AGº = 34. kJ
Now suppose a reaction vessel is filled with 4.19 atm of ammonia (NH3) and 9.94 atm of nitrogen (N2) at 378. °C. Answer the following questions about this
system:
rise
Under these conditions, will the pressure of NH 3 tend to rise or fall?
☐ x10
fall
Х
Is it possible to reverse this tendency by adding H₂?
In other words, if you said the pressure of NH 3 will tend to rise, can that
be changed to a tendency to fall by adding H₂? Similarly, if you said the
pressure of NH3 will tend to fall, can that be changed to a tendency to
rise by adding H₂?
If you said the tendency can be reversed in the second question, calculate
the minimum pressure of H₂ needed to reverse it.
Round your answer to 2 significant digits.
yes
no
atm
00.
18
Ar
무ㅎ
?
Identifying the major species in weak acid or weak base equilibria
The preparations of two aqueous solutions are described in the table below. For each solution, write the chemical formulas of the major species present at
equilibrium. You can leave out water itself.
Write the chemical formulas of the species that will act as acids in the 'acids' row, the formulas of the species that will act as bases in the 'bases' row, and the
formulas of the species that will act as neither acids nor bases in the 'other' row.
You will find it useful to keep in mind that HF is a weak acid.
2.2 mol of NaOH is added to
1.0 L of a 1.4M HF
solution.
acids:
П
bases:
Х
other: ☐
ப
acids:
0.51 mol of KOH is added to
1.0 L of a solution that is
bases:
1.3M in both HF and NaF.
other: ☐
00.
18
Ar
Using reaction free energy to predict equilibrium composition
Consider the following equilibrium:
N2O4 (g) 2NO2 (g)
AG⁰ = 5.4 kJ
Now suppose a reaction vessel is filled with 1.68 atm of dinitrogen tetroxide (N204) at 148. °C. Answer the following questions about this system:
rise
Under these conditions, will the pressure of N2O4 tend to rise or fall?
x10
fall
Is it possible to reverse this tendency by adding NO2?
In other words, if you said the pressure of N2O4 will tend to rise, can that
be changed to a tendency to fall by adding NO2? Similarly, if you said the
pressure of N2O4 will tend to fall, can that be changed to a tendency to
rise by adding NO2?
If you said the tendency can be reversed in the second question, calculate
the minimum pressure of NO 2 needed to reverse it.
Round your answer to 2 significant digits.
yes
no
0.42 atm
☑
5
0/5
?
مله
Ar
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, chemistry and related others by exploring similar questions and additional content below.
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Atomic Number, Atomic Mass, and the Atomic Structure | How to Pass ChemistryThe Nucleus: Crash Course Chemistry #1; Author: Crash Course;https://www.youtube.com/watch?v=FSyAehMdpyI;License: Standard YouTube License, CC-BY