Answer:
7
Explanation:
Let x represent the number of moles of water in the hydrated salt i.e MgSO₄.xH₂O
The following data were obtained from the question:
Mass of MgSO₄.xH₂O = 1.547 g
Mass of anhydrous MgSO₄ = 0.7554 g
Mole of H₂O = x =?
Next, we shall determine the mass of water, H₂O in the hydrated salt, MgSO₄.xH₂O. This can be obtained as follow:
Mass of MgSO₄.xH₂O = 1.547 g
Mass of anhydrous MgSO₄ = 0.7554 g
Mass of H₂O =?
Mass of H₂O = (Mass of MgSO₄.xH₂O) – (Mass of anhydrous MgSO₄)
Mass of H₂O = 1.547 – 0.7554
Mass of H₂O = 0.7916 g
Finally, we shall determine the value of the x as illustrated below:
Mass of MgSO₄.xH₂O = 1.547 g
Molar mass of MgSO₄.xH₂O = 24 + 32 + (16×4) + x[(2×1) + 16]
= 24 + 32 + 64 + x(2 + 16)
= 120 + 18x
Mass of H₂O = 0.7916 g
Molar mass of xH₂O = 18x
Molar Mass of xH₂O/ Molar mass of MgSO₄.xH₂O = mass of xH₂O /Mass of MgSO₄.xH₂O
18x/ 120 + 18x = 0.7916/1.547
Cross multiply
0.7916 (120 + 18x) = 18x × 1.547
94.992 + 14.2488x = 27.846x
Collect like terms
94.992 = 27.846x – 14.2488x
94.992 = 13.5972x
Divide both side by 13.5972
x = 94.992 / 13.5972
x = 7
Thus, the formula for the hydrated salt, MgSO₄.xH₂O is MgSO₄.7H₂O
Number of moles of water, H₂O in the hydrated salt MgSO₄.7H₂O is 7.
The number of moles of attached water molecules is 7.
Mass of hydrated MgSO4 = 1.547 grams
Mass of anhydrous MgSO4 = 0.7554 grams
Number of moles of hydrated MgSO4 = 1.547 grams/120 + 18x
Number of moles of anhydrous MgSO4 = 0.7554 grams /120
Number of moles of anhydrous salt = Number of moles of hydrated salt
0.7554 grams /120 = 1.547 grams/120 + 18x
0.7554(120 + 18x) = 1.547 × 120
90.6 + 13.6x = 185.6
185.6 - 90.6 /13.6 = x
x = 7
The number of moles of attached water molecules is 7.
Learn more about water molecules:https://brainly.com/question/1195122
A gas mixture contains HBr, NO2, and C2H6 at STP. If a tiny hole is made in the container, which gas will effuse fastest? NO2 C2H6 HBr They all effuse at the same rate. Which gas molecules have the highest average kinetic energy at this temperature? HBr NO2 C2H6 They all have the same average kinetic energy.
Answer:
C2H6
Explanation:
Let us first consider the molar Masses of each gas
HBr - 80.91 g/mol
NO2 - 46.0055 g/mol
C2H6 - 30.07 g/mol
We must remember that the greater the molar mass of a gas the lesser its velocity and average kinetic energy.
Looking at the gases listed, C2H6 have the highest average kinetic energy at this temperature since it has the lowest molecular mass. This reasoning is directly derived from Graham's law of diffusion in gases.
Hence C2H6 will effuse fastest when a hole is made in the container. It also possess the greatest average kinetic energy because it has the lowest molecular mass.
For the solution resulting from dissolved 0.32 g of naphthalene (C10H8) in 25 g of benzene (C6H6) at temperature of 26.1°C, calculate the vapor pressure lowering, the boiling point elevation, and the freezing point depression. The vapor pressure of benzene at the temperature of the experiment is 100 torr. (Kf of benzene = 2.67 °C/m, Kb of benzene = 5.12 °C/m)
Answer:
See explanation
Explanation:
Number of moles of naphthalene = 0.32g/128.1705 g/mol = 0.0025 moles
Molality = number of moles/ mass of Solvent in kilograms
Molality = 0.0025/0.025 Kg
Morality = 0.1 m
But
∆T= K × i × m
Where ∆T = boiling point elevation
i= number of particles (this is equal to 1 because naphthalene is molecular and not ionic)
m= molality of naphthalene = 0.1 m
K= boiling point elevation constant = 5.12 °C/m
∆T= 5.12 °C/m ×0.1 = 0.512°C
For freezing point depression
∆T= K× i × m
Where ∆T= freezing point depression
i= number of particles (this is equal to 1 because naphthalene is molecular and not ionic)
m= molality of naphthalene = 0.1 m
K= freezing point depression constant = 2.67 °C/m
∆T= 2.67 °C/m ×0.1 = 0.267°C
From Raoult's law;
∆P = XBPA°
Where;
∆P = vapour pressure lowering
XB = mole fraction of solute
PA° = vapour pressure of pure solvent
Number of moles of solvent = mass/molar mass = 25g/ 78 g/mol= 0.3205 moles
Total number of moles = number of moles of solute + number of moles of solvent = 0.0025 moles + 0.3205 moles = 0.323 moles
Mole fraction of solute = 0.0025 moles/0.323 moles = 0.0077
Vapour pressure of benzene = 100 torr
Therefore;
∆P = 0.0077 × 100torr = 0.77 torr
Hence;
∆P = 0.77 torr
is used to locate and track severe storm
Answer:
Weather radar is used to locate and track severe storm.
Elements with similar chemical properties are organized in the same
A.) Group
B.) Period
C.) Electron Shell
D.) Row
Answer:
electron shell is the answer
Which of the following is true?
A) The closer an electron is to the nucleus, the higher its energy level.
B) The closer an electron is to the nucleus, the lower its energy level.
C) The closer an electron is to the nucleus, the more its energy level fluctuates.
D) There is no relationship between proximity to the nucleus and the energy level of an electron
Answer:
B) The closer an electron is to the nucleus the lower it's energy level.
Explanation:
This is because the attractive force for electrons to the nucleus is stronger. Thus, the orbital energy becomes less.
True or false: BrF5(aq) is a good insulator.
Answer:
true
hope this helps :)
Explanation:
True, [tex]BrF_5[/tex] (aq) is a good insulator.
What is an insulator?A material or an object that does not easily allow heat, electricity, light, or sound to pass through it.
Bromine pentafluoride appears as a colourless, fuming liquid with a pungent odour. Used to make other chemicals and in rockets.
Hence, [tex]BrF_5[/tex] (aq) is a good insulator.
Learn more about insulators here:
https://brainly.com/question/24909989
#SPJ2
What is the pressure if the height of a column of mercury is 0.20 m and the density of mercury is 13,600 kg/m3? (remember, gravity is 9.81 m/s2)
Answer:
[tex]p=26683.2Pa[/tex]
Explanation:
Hello,
In this case, since the pressure is computed via:
[tex]p=h*\rho*g[/tex]
Whereas h is the 0.520-m height, [tex]\rho[/tex] is the 13600-kg/m³ density and the g the 9.81-m/s² gravity. Thus, the pressure in Pa is:
[tex]p=0.20m*13,600 \frac{kg}{m^3} *9.81\frac{m}{s^2} \\\\p=26683.2\frac{kg*\frac{m}{s^2} }{m^2} =26683.2\frac{N}{m^2}\\ \\p=26683.2Pa[/tex]
Best regards.
Is a diamond a homogeneous or heterogeneous mixture or a substance
Answer:
heterogeneous
Explanation:
It's a heterogeneous mixture. Diamond is made of just one element: carbon. Each carbon atom in diamond is connected to four other carbon atoms, in a crystal that extends on and on. There are other forms of pure carbon where the atoms are bonded differently, notably charcoal and graphite.
Soil is an example of a:
a. solution
b. heterogeneous mixture
c. solid solution
Answer:
Heterogeneous mixture
Explanation:
Soil is composed of small pieces of a variety of materials, so it is a heterogeneous mixture.
The amount of force that is exerted on a balloon by the gas inside the balloon is.
O A) temperature
OB) prlessure
O C) volume
O D) heat
Answer:
pressure
Explanation:
pressure is the amount of force exerted on an area. when you blow up the balloon you're filling it with gas particles. the gas particles move freely within the balloon and may collide with one another exerting pressure on the inside of the balloon.
The pressure of the gas is the amount of force that is exerted on a balloon by the gas inside the balloon. Therefore, option B is correct.
What is pressure?Pressure can be described as the force applied perpendicular to the surface of a body per unit area. Pressure can be defined as a standard mechanical quantity and is derived from a unit of force divided by a unit of area.
The SI unit of measurement of pressure, the pascal (Pa) or Newton per square meter (N/m²). Pressure can be defined as the amount of force exerted perpendicular to the surface per unit area.
Mathematically, the pressure exerted by force can be calculated as:
[tex]{\displaystyle p={\frac {F}{A}}}[/tex]
where, p is the pressure, F is the magnitude of the normal force, and A is the area of the surface.
Therefore, the amount of force that is exerted on the balloon by the gas inside the balloon is equal to pressure.
Learn more about pressure, here:
https://brainly.com/question/27637460
#SPJ2
If 25.6 mL isopropyl alcohol fully decomposes, what mass of H2 is formed? The density of isopropyl alcohol is 0.785 g/mL. g
Answer:
The correct answer is 0.67 g H₂
Explanation:
Isopropyl alcohol (C₃H₇OH) can decompose to give acetone (C₂H₆OH) and hydrogen gas (H₂) according to the following chemical equation:
C₃H₇OH (g) ⇒ C₂H₆CO(g) + H₂(g)
We can calculate the initial mass of isopropyl alcohol from the density and volume data:
density = m/V = 0.785 g/mL
⇒ m = density x V = 0.785 g/mL x 25.6 mL = 20.096 g C₃H₇OH
According to the chemical equation 1 mol of C₃H₇OH gives 1 mol H₂. The molar mass of C₃H₇OH is:
molar mass C₃H₇OH = (12 g/mol x 3) + (1 g/mol x 7) + 16 g/mol + 1 g/mol = 60 g/mol
molar mass H₂ = 1 g/mol x 2 = 2 g/mol
So, we obtain: 2 g H₂ from 60 g C₃H₇OH. We multiply this stoichiometric ratio (2 g H₂/60 g C₃H₇OH) by the initial mass of C₃H₇OH to obtain the mass of H₂ is formed:
20.096 g C₃H₇OH x (2 g H₂/60 g C₃H₇OH) = 0.6698 g ≅ 0.67 g H₂
Which element contains four electrons in its third and outer main energy level?
Answer:
valence electrons
Explanation:
The valence electrons are the outer most electrons and the principal energy level in which they belong will vary for .
The chemical element which contains four (4) electrons in its third and outer main energy level is: Silicon (Si).
An electron shell can be defined as the outermost shell of an atom of a chemical element around the atomic nucleus.
Hence, an electron shell is an orbital that is typically accompanied by electrons around the nucleus of an atom.
A sublevel is also referred to as an orbital and it can be defined as an energy level that is associated with the electrons found outside the atomic nucleus.
In Chemistry, there are four main (4) types of sublevel and these are:
s orbital (sublevel): it has one (1) orbital i.e 1s.p orbital (sublevel): it has three (3) orbitals.d orbital (sublevel): it has five (5) orbitals.f orbital (sublevel): it has seven (7) orbitals.In the third (3rd) energy level, there are only three (3) sublevels and these are; s, p and d sublevels.
Silicon is a chemical element that is found in group (4) of the periodic table because it has four (4) electrons in its third and outermost shell.
In its ground state, Silicon (Si) contains the following number of electrons:
Two electrons in its first (n = 1) energy level. Eight electrons in the second (n = 2) energy level.Lastly, it contains four (4) electrons in its third (n = 3) and outer main energy level.Read more: https://brainly.com/question/18214726
What is the atomic number of arsenic (As)?
O A. 33
O B. 15
C. 75
D. 4
SUB
Answer:
33
Explanation:
I need help on this. It’s kinda confusing...
Answer: here u go
Explanation:
A. 3.7 x 10^4
B. 4.56 × 10^-8
C. 8.01 × 10^6
Work for A:
Step 1
To find a, take the number and move a decimal place to the right one position.
Original Number: 37,000
New Number: 3.7000
Step 2
Now, to find b, count how many places to the right of the decimal.
New Number: 3 . 7 0 0 0
Decimal Count: 1 2 3 4
There are 4 places to the right of the decimal place.
Step 3
Building upon what we know above, we can now reconstruct the number into scientific notation.
Remember, the notation is: a x 10b
a = 3.7 (Please notice any zeroes on the end have been removed)
b = 4
Now the whole thing:
3.7 x 104
Step 4
Check your work:
104 = 10,000 x 3.7 = 37,000
Work for B:
Step 1
To find a, take the number and move a decimal place to the right one position.
Original Number: 456
New Number: 0.0000000456
Step 2
Now, to find b, count how many places to the right of the decimal.
New Number: 0 . 0 0 0 0 0 0 0 4 5 6
Decimal Count: 1 2 3 4 5 6 7 8 9 10
There are 2 places to the right of the decimal place.
Step 3
Building upon what we know above, we can now reconstruct the number into scientific notation.
Remember, the notation is: a x 10b
a = 4.56
b = 2
Now the whole thing:
4.56 x 102
Step 4
Check your work:
102 = 100 x 4.56 = 456
Work for C:
Step 1
To find a, take the number and move a decimal place to the right one position.
Original Number: 8,010,000
New Number: 8.010000
Step 2
Now, to find b, count how many places to the right of the decimal.
New Number: 8 . 0 1 0 0 0 0
Decimal Count: 1 2 3 4 5 6
There are 6 places to the right of the decimal place.
Step 3
Building upon what we know above, we can now reconstruct the number into scientific notation.
Remember, the notation is: a x 10b
a = 8.01 (Please notice any zeroes on the end have been removed)
b = 6
Now the whole thing:
8.01 x 106
Step 4
Check your work:
106 = 1,000,000 x 8.01 = 8,010,000
Hope this helps!
Has 121 nuetrons and 80 electrons plz help i will pick you as brainliest
Answer:
Mercury Atom
Explanation:
If you are talking about what has 121 neutrons and 80 electrons, then it would be a Mercury Atom. Hope this helps!
2NH.
N2 + 3H2
Reactants
Product
On the balanced equation above, how many
atoms of each element are in the reactant?
N =
H =
Answer:
N=2
H=6
Explanation:
1.Balance a chemical equation in terms of moles.
2.Use the balanced equation to construct conversion factors in terms of moles.
3.Calculate moles of one substance from moles of another substance using a balanced chemical equation.
The law of conservation of matter says that matter cannot be created or destroyed. In chemical equations, the number of atoms of each element in the reactants must be the same as the number of atoms of each element in the products.
(P.s it could also be where you have to solve it in which you have to simplify it first then solve it.) like adding them all up.
Hope this is the answer. :)
Define a function compute_gas_volume that returns the volume of a gas given parameters pressure, temperature, and moles. Use the gas equation PV
Answer:
def compute_volume(pressure,moles,temperature):
volume = (8.314 * moles * temperature)/pressure
print("Volume: "+str(volume))
Explanation:
This line defines the function
def compute_volume(pressure,moles,temperature):
This line calculates the volume
volume = (8.314 * moles * temperature)/pressure
This line prints the calculated volume
print("Volume: "+str(volume))
What are the signs that you are getting nervous 18 POINTS )
17. What is the average atomic mass of the following isotopic mixture - 22.00% of 159.3 g/mole; 78.00% of
161.2g/mole?
The average atomic mass is given by the individual atomic masses of the isotope of the element and its percentage. The average atomic mass of the isotopic mixture is 159.8 g/mole.
What are isotopes?Isotopes are atoms of the same element that have the same number of protons in their nucleus but have a different number of neutrons that alters their atomic masses. The relative abundance of the isotope of the element affects the average atomic mass of the mixture.
The formula for average atomic mass for the mixture of isotopes is given as:
Average atomic mass = ∑ (mass × abundance)
Given,
Abundance of isotope 1 = 22.00 %
Mass of isotope 1 = 159.3 g/mole
Abundance of isotope 2 = 78.00 %
Mass of isotope 2 = 161.2g/mole
Substituting values in the formula of average atomic mass as:
Average atomic mass = isotope 1 (mass × abundance) + isotope 2 (mass × abundance)
= (0.22) × (159.3) + (0.78) × (161.2)
= 34.046 + 125.736
= 159.8 g/mole
Therefore, the average atomic mass of the mixture of the two isotopes is 159.8 g/mole.
Learn more about isotopes and average mass, here:
https://brainly.com/question/2159355
#SPJ2
write the equation for the beta decay of 53/26 FE
Answer:
53/26Fe = 0/-1,B + 53/27 Co
Assuming constant pressure, rank these reactions from most energy released by the system to most energy absorbed by the system, based on the following descriptions:
Surroundings get colder and the system decreases in volume.
Surroundings get hotter and the system expands in volume.
Surroundings get hotter and the system decreases in volume.
Surroundings get hotter and the system does not change in volume.
A mole of X reacts at a constant pressure of 43.0 atm via the reaction.
X(g)+4Y(g)→2Z(g), ΔH∘=−75.0 kJ
Also assume that the magnitude of the volume and temperature changes are similar among the reactions. Rank from most energy released to most energy absorbed. To rank items as equivalent, overlap them. View Available Hint(s)
Answer:
The options are
A.Surroundings get colder and the system decreases in volume.
B.Surroundings get hotter and the system expands in volume.
C.Surroundings get hotter and the system decreases in volume.
D.Surroundings get hotter and the system does not change in volume.
From the Most energy released to the most absorbed , the order is
B. Surroundings get hotter and the system expands in volume.
D. Surroundings get hotter and the system does not change in volume.
C. Surroundings get hotter and the system decreases in volume.
A. Surroundings get colder and the system decreases in volume.
Write the half-reaction for ribose conversion to CO2. Is it an oxidation- or reduction- half reaction
Answer:
[tex]5H_2O+C_5H_{10}O_5\rightarrow 5CO_2+20H^++20e^-[/tex]
Explanation:
Hello.
In this case, when ribose (C₅H₁₀O₅) yields carbon dioxide (CO₂) we write:
[tex]C_5H_{10}O_5\rightarrow CO_2[/tex]
Which needs to be balanced by adding water and hydrogen ions:
[tex]5H_2O+C_5H_{10}O_5\rightarrow 5CO_2+20H^++20e^-[/tex]
You can also see that there are 20 transferred electrons, since the carbon atoms in the ribose have 0 as their oxidation state and the carbon atoms in the carbon dioxide have +4 as the oxidation state, thus, each carbon transfers 4 electrons, a five carbon atoms transfer 20 electrons overall.
In such a way, since the carbon is increasing its oxidation state, such half reaction is an oxidation half reaction.
Best regards.
What is the dependent variable? Be specific. *
If a teacher washes the tops of the student
desks with rubbing alcohol daily, the
spread of germs in the classroom may be
diminished.Be specific when you write your answer HELPPPPP I NEED IT ASAP!
How many grams are in 9.97 moles of Be(NO3)2?
Use two digits past the decimal for all values.
Answer:
1,869.97 grams of Be(NO3)2
Explanation:
Be(NO3)2 = Be N2 O6
Be=9.012182g/mole
N2=28.0134g/mole
O6=96g/mole
therefore Be(NO3)2 gives you 187.56g in one mole
so 9.97 moles means there is 9.97 times more
9.97mole Be(NO3)2 * 187.56g Be(NO3)2/1mole Be(NO3)2 = 1,869.97g of Be(NO3)2
When drawing the Lewis structure of a molecule, start by determining the total number of available valence based on each element's ___________ group number. Then, use the total number of electrons needed for each element to be stable, generally based on________ its charge, to determine the____________ ionic charge by finding the difference between the number of needed and available electrons divided by two.
Next, identify the central atom, which is the element with the __________ fewest valence electrons other than hydrogen. Finally, arrange the number of bonds around the central atom to fulfill the stable number of electrons for each element.
Answer:
Group number, octet's rule, total number of bonds and fewest valence electrons.
Explanation:
Hello,
For the given statement is answer is bolded:
"When drawing the Lewis structure of a molecule, start by determining the total number of available valence based on each element's group number. Then, use the total number of electrons needed for each element to be stable, generally based on the octet's rule its charge, to determine the total number of bonds by finding the difference between the number of needed and available electrons divided by two.
Next, identify the central atom, which is the element with the fewest valence electrons other than hydrogen. Finally, arrange the number of bonds around the central atom to fulfill the stable number of electrons for each element".
For the first one, it is widely known that the group number provides the number of valence electrons as nitrogen is in group VA and it has five valence electrons, chlorine is in grou´p VIIA and it has seven valence electrons and so on.
For the second one, it is also known that the octet's rule limit the amount of bonds as it has been demonstrated that each compound can hold up to 8 electrons overall excluding some exceptions.
For the third one, based on the octet's rule, an element must have as much bonds as missing electrons to complete eight, for instance, carbon has four valence electrons, so it need four bonds (each one providing one valence electron) in order to attain the octet.
Finally, the central atom must have the fewest number of valence electrons as it shows the other bonds and elements attaining the octet. Usually, the central atom is not demanded to get 8 electrons, for instance in AlCl₃, which is:
[tex]\ \ \ \ \ Cl-Al-Cl\\.\ \ \ \ \ \ \ \ \ \ \ \ \ |\\.\ \ \ \ \ \ \ \ \ \ \ \ Cl[/tex]
Has aluminum as the central one due to the fact that it has three valence electrons whereas chlorine seven and it does not attain the octet.
Best regards.
Identify the correct net ionic equation for the reaction that occurs when solutions of Pb(NO3)2 and NH4Cl are mixed.
Answer:
Pb2+(aq) + 2Cl–(aq) ----> PbCl2(s)
Explanation:
The net ionic equation shows the main reaction that takes place in a system. Hence, a net ionic equation focusses only on those species that actually participate in the reaction.
For the reaction between Pb(NO3)2 and NH4Cl , the net ionic equation is;
Pb^+(aq) + 2Cl^-(aq) ---> PbCl2(s)
The correct net ionic equation for the reaction that occurs when solutions of Pb(NO₃)₂ and NH₄Cl are mixed is
Pb⁺(aq) + 2Cl¯(aq) —> PbCl₂(s)To know the the correct net ionic equation for the reaction that occurs when solutions of Pb(NO₃)₂ and NH₄Cl are mixed, we shall write the net ionic equation for the reaction. This is illustrated below:
Pb(NO₃)₂(aq) —> Pb⁺(aq) + NO₃¯(aq)
NH₄Cl(aq) —> NH₄⁺(aq) + Cl¯(aq)
Pb(NO₃)₂(aq) + NH₄Cl(aq) —>
Pb⁺(aq) + NO₃¯(aq) + NH₄⁺(aq) + Cl¯(aq) —> PbCl₂(s) + NO₃¯(aq) + NH₄⁺(aq)
Cancel the spectator ions (i.e NO₃¯ and NH₄⁺) and write 2 before Cl¯ to obtain the net ionic equation as shown below:
Pb⁺(aq) + 2Cl¯(aq) —> PbCl₂(s)Thus, the correct net ionic equation for the reaction that occurs when solutions of Pb(NO₃)₂ and NH₄Cl are mixed is
Pb⁺(aq) + 2Cl¯(aq) —> PbCl₂(s)Learn more: https://brainly.com/question/21883718
Products made of plastic can last a very long time. Explain both the positive and negative effects of plastic being long-lasting. thank uuu
Answer:Because plastic products are durable, they can last for a long time. This makes them affordable because they do not have to be replaced often. On the other hand, the popular use of plastics means that many plastics are thrown away. Plastics litter the ocean, causing harm to marine birds and mammals. Plastic breaks down into plastic dust, which can last for up to a thousand years.
^^^^^copy and paste this part^^^^^
Explanation:Plastic is he hardest material to break down with harm to sea life and land life they may be affordable but costly to the environment.
Help
Save & Exit
Submit
Rank the following elements in order from least to most number of moles of atoms in a 10.0 g sample: Sn, Si, Se, S
Answer:
[tex]\rm Sn[/tex], [tex]\rm Se[/tex], [tex]\rm S[/tex], [tex]\rm Si[/tex].
Explanation:
The relative atomic mass of an element is numerically equal to the mass (in grams) of one mole of its atoms. This quantity can help estimate the number of moles of atoms in each of these four [tex]10.0\; \rm g[/tex] samples.
Look up the relative atomic mass for each of these four elements (on a modern periodic table.)
[tex]\rm Si[/tex]: [tex]28.085[/tex].[tex]\rm S[/tex]: [tex]32.06[/tex].[tex]\rm Se[/tex]: [tex]78.971[/tex].[tex]\rm Sn[/tex]: [tex]118.710[/tex].The relative atomic mass of [tex]\rm Si[/tex] is (approximately) [tex]28.085[/tex]. Therefore, the each mole of silicon atoms would have a mass of approximately [tex]28.085\; \rm g[/tex]. How many moles of silicon atoms would there be in a [tex]10.0\; \rm g[/tex] sample?
Given:
[tex]m(\rm Si) = 10.0\; \rm g[/tex]. [tex]M(\mathrm{Si}) = 28.085\; \rm g \cdot mol^{-1}[/tex].Number of mole of silicon atoms in the sample: [tex]\displaystyle n(\mathrm{Si}) = \frac{m(\mathrm{Si})}{M(\mathrm{Si})} = \frac{10.0\; \rm g}{28.085\; \rm g \cdot mol^{-1}}\approx 0.356\; \rm mol[/tex].
Similarly:
[tex]\displaystyle n(\mathrm{S}) = \frac{m(\mathrm{S})}{M(\mathrm{S})} = \frac{10.0\; \rm g}{32.06\; \rm g \cdot mol^{-1}}\approx 0.312\; \rm mol[/tex].
[tex]\displaystyle n(\mathrm{Se}) = \frac{m(\mathrm{Se})}{M(\mathrm{Se})} = \frac{10.0\; \rm g}{78.971\; \rm g \cdot mol^{-1}}\approx 0.127\; \rm mol[/tex].
[tex]\displaystyle n(\mathrm{Sn}) = \frac{m(\mathrm{Sn})}{M(\mathrm{Sn})} = \frac{10.0\; \rm g}{118.710\; \rm g \cdot mol^{-1}}\approx 0.0842\; \rm mol[/tex].
Therefore, among these [tex]10.0\; \rm g[/tex] samples:
[tex]n(\mathrm{Sn}) < n(\mathrm{Se}) < n(\mathrm{S}) < n(\mathrm{Si})[/tex].
It is not a coincidence that among these four samples, the one with the fewest number of atoms corresponds to the element with the largest relative atomic mass.
Consider two elements, with molar mass [tex]M_1[/tex] and [tex]M_2[/tex] each. Assume that [tex]n_1[/tex] moles and [tex]n_2[/tex] moles of atoms of each element were selected, such that the mass of both samples is [tex]m[/tex]. That is:
[tex]m = n_1\cdot M_1[/tex].
[tex]m = n_2\cdot M_2[/tex].
Equate the right-hand side of these two equations:
[tex]n_1 \cdot M_1 = n_2\cdot M_2[/tex].
[tex]\displaystyle \frac{n_1}{n_2} = \frac{M_2}{M_1} = \frac{1/M_1}{1/M_2}[/tex].
In other words, the number of moles atoms in two equal-mass samples of two elements is inversely proportional to the molar mass of the two elements (and hence inversely proportional to the formula mass of the two elements.) That explains why in this question, the sample containing the smallest number of atoms corresponds to element with the largest relative atomic mass among those four elements.
__________ 5. Chemical equilibrium is the result of A. all of the reactants being converted into products. B. stoppage of further reaction. C. formation of products equal in mass to the mass of the reactants. D. opposing reactions attaining equal rates. E. a loss of pressure in the system.
Answer:
The correct option is C
Explanation:
Chemical equilibrium is a state in which there is no net change in the amount of reactant and products formed over time. This reaction is a reversible reaction, hence the reaction can keep proceeding in either direction until the products formed are equal in mass to that of the reactants or the products been reversed back to the reactants until both sides (product and reactant) achieve equal mass.
i need to know how to get a boy to like me
Answer:
To get a boy to like you you have to 1.dress up cutely
2.talk to him ask him what he likes
3. wear a little bit of make-up not to much
4. wear you hair down and have a little bit of hair on your chest
5. Be really confident and don't wait till a really longg time and mess up like i did.
Explanation:
Answer:
Put your hair down. Also, dont use too much makeup. Just wear mascara and lipgloss. Be kind. Be confident.
Explanation:
If u wear to much makeup he will think ur a try-hard. Stop trying to be cool, it's just dumb. If ur rude, then hes gonna think that u dont like him.