Answer:
[tex]\%_{Rb-85}=33.9\%[/tex]
[tex]\%_{Rb-87}=66.1\%[/tex]
Explanation:
Hello,
In this case, for the natural occurring isotopes we equal the average atomic mass via:
[tex]86.231=84.911*\%_{Rb-85}+86.909*\%_{Rb-87}[/tex]
Thus, since both percentages of abundance must turn out 100%, we can write:
[tex]\%_{Rb-85}+\%_{Rb-87}=100\%\\\\\%_{Rb-85}=100\%-\%_{Rb-87}[/tex]
So we can write:
[tex]86.231=84.911*(100\%-\%_{Rb-87})+86.909*\%_{Rb-87}[/tex]
Solving for the percentage of abundance of Rb-87:
[tex]86.231=84911.00\%-84.911\%_{Rb-87}+86.909*\%_{Rb-87}\\\\\%_{Rb-87}=\frac{86.231-84.911}{-84.911+86.909}\\ \\\%_{Rb-87}=66.1\%[/tex]
Therefore, the percentage of abundance of Rb-85 turns out:
[tex]\%_{Rb-85}=100\%-66.1\%\\\\\%_{Rb-85}=33.9\%[/tex]
Best regards.
Considering the definition of atomic mass, isotopes and atomic mass of an element, the percentages of the isotopes in this sample are:
percent of Rb-87= 66.07%percent of Rb-85 = 33.93%
First of all, the atomic mass (A) is obtained by adding the number of protons and neutrons in a given nucleus of a chemical element.
The same chemical element can be made up of different atoms, that is, their atomic numbers are the same, but the number of neutrons is different. These atoms are called isotopes of the element.
On the other hand, the atomic mass of an element is the weighted average mass of its natural isotopes. In other words, the atomic masses of chemical elements are usually calculated as the weighted average of the masses of the different isotopes of each element, taking into account the relative abundance of each of them.
In this case, a certain sample of rubidium has just two isotopes, 85Rb (mass = 84.911amu) and 87Rb (mass = 86.909amu). Then, the average mass of lithium can be calculated as:
84.911× percent of Rb-85 + 86.909× percent of Rb-87= 86.231
Since both abundance percentages must be 100%, you can write:
percent of Rb-85 + percent of Rb-87= 100
Then:
percent of Rb-85 = 100% - percent of Rb-87
So, replacing this expression in the first equation:
84.911× (100% - percent of Rb-87) + 86.909× percent of Rb-87= 86.231
Solving:
84.911×100% - 84.911× percent of Rb-87 + 86.909× percent of Rb-87= 86.231
8491.1% -84.911× percent of Rb-87 + 86.909× percent of Rb-87= 86.231
-84.911× percent of Rb-87 + 86.909× percent of Rb-87= 86.231 - 8491.1%
-84.911× percent of Rb-87 + 86.909× percent of Rb-87= 86.231 - 84.911
1.998× percent of Rb-87= 86.231 - 84.911
1.998× percent of Rb-87= 1.32
percent of Rb-87= 1.32÷ 1.998
percent of Rb-87= 0.6607
percent of Rb-87= 66.07%
Therefore, the percentage of abundance of Rb-85 is:
percent of Rb-85 = 100% - percent of Rb-87
percent of Rb-85 = 100% - 66.07%
percent of Rb-85 = 33.93%
Finally, the percentages of the isotopes in this sample are:
percent of Rb-87= 66.07%percent of Rb-85 = 33.93%Learn more:
brainly.com/question/14403750?referrer=searchResults brainly.com/question/10043246?referrer=searchResults brainly.com/question/15553207?referrer=searchResults1. What is the relationship between science and society?
Which of the following alkyl halides has the smallest molecular dipole moment?
A) CH3F
B) CH3Cl
C) CH2I2
D) CH2Cl2
E) CF4
Answer:
Explanation:
B
forces can make things move faster or_______them down.
Answer:
Slower
Explanation:
Different forces, such as gravity, can affect an object in many ways.
Scenario 1: A car is climbing a hill and then starts to coast.
Here, when the car starts to not accelerate anymore, gravity could pull it to slow down and eventually stop.
Scenario 2: A car is speeding downwards.
Here, when the car isn't on the gas pedal, gravity could act upon the car and make it go faster.
forces can make things move faster or slower them down.
What are the differences between ionic and covalent (molecular) compounds?
Answer: Ionic compound are made by strong electrostatic interactions in the middle of ion , which will result in higher melting points and electrical conductivity when being compared to covalent compounds . covalent counds have bonds where the electrons are shared allying atoms .
Hoped I Helped-
Sleepy~
You have been given an orange liquid and told to describe its properties.
What methods would you use to observe, measure, and describe the
physical properties of this orange liquid without changing it?
Answer:
The correct answer would be - observing with the help of five senses.
Explanation:
To find and describe the physical properties of the given substance or the solution or liquid students can observe using their five senses. By looking at the liquid one can find its state and color, by smelling students can find the odor of the sample, by touching it one can observe and describe the texture.
Fluidity can also be measure by the touch if the solution is viscous or free-floating. By using a thermometer and using a graduated cylinder one can find the temperature at room temperature and the weight of substance respectively.
Things that you learn through your senses during an experiment are
A. hypotheses
B. controls
C. observations
D. conclusion
Answer:
c- observations
hope this helps
Explanation:
please helpp neep asap ik its late at night but i just need this one page and i can rest
Answer:
15. Velocity = 3 X 10^8
Distance = 1580 m
time = distance / velocity
t = 1580 / 3 * 10^8
t = 1580 * 10^-8 / 3
t = 158 * 10^-7/3
t = 5.26 * 10^-8 seconds
16. Converting the distance to 'm'
Given distance (in miles), multiplying by 1.609 to convert to km and also multiplying by 1000 to convert to 'm'
s= 4.8 * 1.609 * 10^7 * 1000
v = 3 * 10^8
t = 4.8 * 1609 * 10^7 / 3 * 10^8
t = 1.6 * 1609 * 10^-1
t = 2574.4 * 10^ -1
t = 2.5744 * 10^-4 s
17. Mass in 1 tsp of medicine = 5 mL at a density of 25 mg/mL
Mass in 1 tsp of medicine = 5 * 25 = 125 mg
Mass prescribed by the doctor = 375 mg
Number of table spoons required = Mass prescribed / Mass in 1 tsp
N = 375/125 = 3 table spoons of the medicine
18. Density of medicine = 400g/ 5mL = 80g / mL
Medicine required = 1500 g
Volume of medicine required = Medicine Required / Density of medicine
Volume = 1500 / 80 = 18.75 mL of medicine is required
Hence, the volume of the suspension should be at least 18.75 mL
19. Volume of 10 drops = 1 mL
Volume of 5 drops = 1/2 mL
The faucet is leaking 5 drops or 1/2 mL water per minute
Number of minutes in a day = 60 * 24 = 1440 minutes in a day
Water leaked in 1440 minutes = 1440 * 1/2 = 720
0.720 L (720 mL) Water leaked from the faucet in a day
Kindly mark Brainliest, Thanks
Match the scientist with their scientific idea.
Substances combine or
break apart to create new,
different substances.
1. Democritus
2. Bernoulli
Gases are formed from tiny
particles so small you can't
see them. The particles are
spread out into a certain
area and move when
people walk through them.
3. Priestley
Matter was made of
different kinds of things.
Answer:
1. Democritus- Matter was made of
different kinds of things.
2. Bernoulli- Gases are formed from tiny particles so small you can't see them. The particles are spread out into a certain area and move when people walk through them.
3. Priestley- Substances combine or
break apart to create new different substances.
Explanation:
1. Democritus was a Greek philosopher regarded to be the "Father of Science". He discovered that all matter were composed of indestructible things he called ATOMOS. Hence, his idea was that Matter was made of different kinds of things (atoms).
2. David Bernoulli, a mathematician, was born in 1700. He contributed immensely to the kinetic molecular theory of gases. In his postulated theory, he gave the idea that gases are formed from tiny particles so small you can't see them. The particles are spread out into a certain area and move when people walk through them.
3. Priestley- Joseph Priestley, born in 1733, is widely known for his discovery of oxygen gas among other gases. His idea was that substances combine or
break apart to create new different substances.
What type of cell is the typical human body cell
Answer:
Red blood cells
Explanation:
An average adult human has somewhere around 25 trillion red blood cells in their body.
Answer:
Heya! Maddie here! The answer is Red Blood Cells.
Explanation:
Hope this helps!
In which of the following compounds is the octet expanded to include 12 electrons?
PC13
H2S
SF6
PCIE
Answer: SF6
Sulfur hexafluoride or sulphur hexafluoride, is an inorganic, colorless, odorless, non-flammable, non-toxic but extremely potent greenhouse gas, and an excellent electrical insulator. SF₆ has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom.
Give the number of significant figures in the following measurement 1278.50
Answer:
5 significant figures all figures are significant except for 0
which two quantities are used to predict gravitational force according to Newton's law of universal gravitation a. mass and speed b. mass and distance c. distance and velocity d. velocity and mass
Answer:
(b). Mass and distance.
Explanation:
The gravitational force between two objects is given by Newton's law of universal gravitation. The formula is as follows :
[tex]F=G\dfrac{m_1m_2}{r^2}[/tex]
Here,
G is universal gravitational constant
r is the distance between two objects
It is very clear that the gravitational force is directly proportional to the product of masses and inversely proportional to the square of the distance between them.
Hence, the two quantities are used to predict gravitational force according to Newton's law of universal gravitation are mass and distance.
Answer:mass and distance
Explanation:
it’s correct
Match the scientist with their scientific idea. Question 2 options: Substances combine or break apart to create new, different substances. Gases are formed from tiny particles so small you can’t see them. The particles are spread out into a certain area and move when people walk through them. Matter was made of different kinds of things. 1. Democritus 2. Bernoulli 3. Priestley
Answer:
1. Democritus - Matter was made of different kinds of things.
2. Bernoulli- Gases are formed from tiny particles so small you can’t see them. The particles are spread out into a certain area and move when people walk through them.
3. Priestley- Substances combine or break apart to create new, different substances.
Explanation:
1. Democritus was a philosopher who because of his immense contribution to atomic theory was regarded as the "FATHER OF SCIENCE". His idea was that matter was made of different kinds of things called which he called ATOMOS meaning ATOM.
2. Daniel Bernoulli was another outstanding mathematician and scientist who played a major part in the kinetic molecular theory of gases via his "HYDRODYNAMICA". His idea, which states that "gases are formed from tiny particles so small you can’t see them. The particles are spread out into a certain area and move when people walk through them"
was based on fluid dynamics.
3. Joseph Priestley is remarkably known for his 1774 discovery of oxygen. His findings that air is a mixture of gases and not just a substance made of one element paved the way for his idea that " Substances combine or break apart to create new, different substances".
Which two parts of the atom are found in nucleus?
Answer:
protons and neutrons are found in nucleus
5) Read each Eco fact. Propose a solution to prevent the environmental problems of the
seaport of troy described in the eco fact.
Answer:
The creation of regulations that limit timber activities and the exploitation of wood can prevent soil erosion in Troy.
Explanation:
The exploitation of the wood was an intense activity and that did not have any regulation that would limit its damages, caused by its exploratory activities.
As the timber market was totally undisciplined, the exploitation of the wood caused a strong deforestation, leaving the soil totally unprotected and susceptible to strong erosion.
Soil erosion has a very negative impact on the environment, requiring regulations to be made to prevent this from happening.
Based on this, we can say that one way to prevent environmental problems in the seaport of troy is by establishing laws and regulations that limit logging activities.
How would you prepare 1.00 L of a 0.50 M solution of each of the following?
HCI from "concentrated" (12 M) reagent.
Answer:
Take approx 41.7 mL of 12-M HCl in a 1.00-L flask and fill the rest of the volume with distilled water.
Explanation:
Hello,
In this case, for the dilution process from concentrated 12-M hydrochloric acid to 1.00 L of the diluted 0.50M hydrochloric acid, the volume of concentrated HCl you must take is computed by considering that the moles remain constant for all dilution processes as shown below:
[tex]n_1=n_2[/tex]
Which can also be written in terms of concentrations and volumes:
[tex]M_1V_1=M_2V_2[/tex]
Thus, solving for the initial volume or aliquot that must be taken from the 12-M HCl, we obtain:
[tex]V_1=\frac{M_2V_2}{M_1} \\\\V_1=\frac{1.00L*0.5M}{12M}\\ \\V_1=0.0417L=41.7mL[/tex]
It means that you must take approx 41.7 mL of 12-M HCl in a 1.00-L flask and fill the rest of the volume with distilled water for such preparation.
Best regards.
At 50 degree C pK_w = 13.26. What is the pH of pure water at this temperature?
a. 6.63
b. 7.00
c. 7.37
d. 13.26
Answer:
6.63
Explanation:
From the relationship;
pH = pKw/2
Pkw = 13.26
Then it follows that;
pH = 6.63
Hence if. pKw = 13.26, the pH = 6.63
What mass of nitrogen is needed to fill an 855 L tank at STP?
Answer:
1068.8 g of N₂ are required.
We can also say, 1.07 kg of N₂
Explanation:
Let's apply the Ideal Gas Law equation to solve the problem:
Formula is P . V = n . R . T
At STP we know, that P is 1 atm and T is 273.15 K. So let's replace the formula:
1 atm . 855 L = n . 0.082 L.atm /mol.K . 273.15 K
(1atm . 855L) / (0.082 L.atm /mol.K . 273.15 K) = n
38.17 moles = n
Let's convert the moles to mass, nitrogen is a dyatomic gas → N₂
Molar mass N₂ = 28 g/mol
38.17 mol . 28 g/mol = 1068.8 g of N₂ are required.
AT STP the 1 moles of gas is equal to the 22.4 L of gas. The mass of the nitrogen gas in the 855 L tank at STP is 1068 g.
The mass of the Nitrogen gas can be calculate using the formula,
[tex]\bold {w = n \times m}\\[/tex]
Where,
w -mass = ?
n - number of moles = [tex]\bold {=\dfrac {855}{22.4} = 38.169\ moles }[/tex] at STP.
m - molar mass [tex]\bold {N_2}[/tex] =
Put the values in the formula,
[tex]\bold {w = 38.169 \times 28 = 1068.73\ g}[/tex]
Therefore, the mass of the nitrogen gas in the 855 L tank at STP is 1068 g.
To know more about STP,
https://brainly.com/question/24050436
2) 183 cg =
kg
5
.00183 kg
0.0183 kg
.183 kg
3) 0.25 kg =
g
Answer:
183 cg = 0.00183 kg
0.25 kg = 250 g
Explanation:
Use conversion factors. 1kg is equal to 1 x 10^5 cg (100000) and 1 kg is equal to 1 x 10^3 grams (1000 grams).
An element can be broken down into simpler means. True or false?
Answer:
They can only be broken down to the Atom like neutron proton and electrons. I hope that help
what is the chemistery
Answer:
Explanation:
Chemistry is the science that studies the composition, structure and properties of matter and the changes it undergoes during chemical reactions and their relationship with energy
Explanation:
Chemistry is the branch of science concerned with the substances of which matter is composed, the investigation of their properties and reactions, and the use of such reactions to form new substances.
1. How many elements are in the following Compound?
C8H10N,O2
Answer:
i believe it is 5
Explanation:
.......
What volume (mL) of 0.135 M NaOH is required to neutralize 13.7 mL of 0.129 M HCl? a: 0.24 b: 13.1 c: 0.076 d: 6.55 e: 14.3
Answer:
The volume (mL) of 0.135 M NaOH that is required to neutralize 13.7 mL of 0.129 M HCl is 13.1 mL (option b).
Explanation:
The reaction between an acid and a base is called neutralization, forming a salt and water.
Salt is an ionic compound made up of an anion (positively charged ion) from the base and a cation (negatively charged ion) from the acid.
When an acid is neutralized, the amount of base added must equal the amount of acid initially present. This base quantity is said to be the equivalent quantity. In other words, at the equivalence point the stoichiometry of the reaction is exactly fulfilled (there are no limiting or excess reagents), therefore the numbers of moles of both will be in stoichiometric relationship. So:
V acid *M acid = V base *M base
where V represents the volume of solution and M the molar concentration of said solution.
In this case:
V acid= 13.7 mL= 0.0137 L (being 1,000 mL= 1 L)M acid= 0.129 MV base= ?M base= 0.135 MReplacing:
0.0137 L* 0.129 M= V base* 0.135 M
Solving:
[tex]V base=\frac{0.0137 L*0.129 M}{0.135 M}[/tex]
V base=0.0131 L = 13.1 mL
The volume (mL) of 0.135 M NaOH that is required to neutralize 13.7 mL of 0.129 M HCl is 13.1 mL (option b).
Please answer this it’s 8th grade science and we are only 1 month into the year!
Answer:
Earth's gravitational pull
Explanation:
Astronauts in the space shuttle float because they are in “free fall” around Earth, just like a satellite or the Moon. Again, it is gravity that provides the centripetal force that keeps them in circular motion.
1. The strength with which an organic compound binds to an adsorbent depends on the strength of the following types of interactions: ion-dipole, dipole-dipole, hydrogen bonding, dipole induced dipole, and van der Waals forces. With silica gel, the dominant interactive forces between the adsorbent and the materials to be separated are_________________.
Answer:
Dipole-dipole interactions
Explanation:
Dipole-dipole interactions occur between two molecules with two polar end- a partially positive end and a partially negative end. The dipoles exists in these molecules due to the difference in the electronegativities of the atoms if the molecule. The positive end of a dipolar molecule will be attracted to the partially negative end of the neighboring molecule.
In the separation of molecules using silica gel as the adsorbent surface, the dominant interactive forces between the adsorbent and the materials to be separated are dipole-dipole interactions. The silica gel have polar SiOH groups on its surface which attracts polar molecules in the material to be separated. These polar molecules are strongly adsorbed to the silica gel surface whereas nonpolar or less polar molecules in the material to be separated are less strongly adsorbed, and thus, are eluted faster than the polar molecules.
Q- 30. The number of grams of solute
30:dissolved in 100 grams of solution
is called:30.09
سولیوٹ کی گرامز :
مقدار جو سلوشن کے 100 گرامز د حل
ہو، یہ پرسینٹیج کہلاتا ہے
ماس /ماس Mass
/
Mass
ماس / واليم Mass
/
Volume
والیم /ماس Volume
/
Mass
والیم و البم Volume
/
Volumne
Answer:
Mass by mass
Explanation:
Because it's telling only about mass in grams
An element has two isotopes. 90% of the isotopes have a mass number of 20 amu, while 10% have a mass number of 22 amu. Calculate the Average Atomic Mass of the element
Explanation:
aam= 90%•20amu+10%•22amu/100
aam= 2020/100
aam= 20.2
Taking into account the definition of atomic mass, isotopes and atomic mass of an element, the average mass of the element is 20.2.
First of all, you have to know that atoms are made up of protons and neutrons in a central nucleus, as well as an electronic cloud (the extra-nuclear zone), a place where there is a greater probability of finding electrons orbiting the nucleus of the atom.
Then, it is neccesary to know that the atomic mass (A) is obtained by adding the number of protons and neutrons in a given nucleus.
The same chemical element can be made up of different atoms, that is, their atomic numbers are the same, but the number of neutrons is different. These atoms are called isotopes of the element.
This is, isotopes are atoms whose atomic nuclei have the same number of protons but different numbers of neutrons.
Because the isotopes of an element have different atomic masses, the relative atomic mass or atomic weight is an average of the atomic masses of the different isotopes in a sample taking into account the relative abundance of each of them.
In this case, 90% of the isotopes have a mass number of 20 amu, while 10% have a mass number of 22 amu. Then, the average mass of the element can be calculated as:
20 amu×0.90 + 22 amu×0.10= 20.2
Finally, the average mass of the element is 20.2.
Learn more:
brainly.com/question/14403750?referrer=searchResults brainly.com/question/10043246?referrer=searchResults brainly.com/question/15553207?referrer=searchResultsWould phosphoric acid or succinic acid be a better buffer at ph5?
Answer:
Explanation:
For the pH value of a buffer solution , the Henderson formula given is as follows
pH = pKa + log [ A⁻] / [AH ]
Now let us discuss about the phosphoric and succinic acid . The phosphoric acid has a pKa value of 2.3 and for succinic acid , the pKa value is 4.2 . The pKa value of succinic acid is more close to 5 . So to achieve pH value of 5 , succinic acid is a better alternative . The value of [ A⁻] / [AH ] is kept almost equal to 1 to increase the buffer capacity .
How many moles of HCl are present in 75.0 mL of a 0.200 M
solution?
Answer:
0.015 mol HCL
Explanation:
Molarity = moles solute/liters solution
Step 1: Define variables
M = 0.200
L = 75.0 mL
m = unknown, x
Step 2: Convert mL to L
1000 mL = 1 L
75.0 mL/1000 mL = 0.075 L
Step 3: Substitute
0.200 M = x mol/0.075 L
Step 4: Find x
x = 0.015 mol HCL
Group one elements, such as lithium, sodium, and
potassium, are known as
OA) alkali metals.
B)
halogens.
C) alkaline earth metals.
D) noble gasses.
Answer:
Alkali Metals
Explanation:
Because they are in group one, but Hydrogen is not an alkali metal.
