the concentration of the radio active isotope potassium-40 in a rock sample is found to be 6.25%. what is the age of the rock

Answers

Answer 1

Answer:

5.0 x 10⁹ years.

Explanation:

It is known that the decay of a radioactive isotope isotope obeys first order kinetics.Half-life time is the time needed for the reactants to be in its half concentration.If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).Also, it is clear that in first order decay the half-life time is independent of the initial concentration.The half-life of K-40 = 1.251 × 10⁹ years.

For, first order reactions:

k = ln(2)/(t1/2) = 0.693/(t1/2).

Where, k is the rate constant of the reaction.

t1/2 is the half-life of the reaction.

∴ k =0.693/(t1/2) = 0.693/(1.251 × 10⁹ years) = 5.54 x 10⁻¹⁰ year⁻¹.

Also, we have the integral law of first order reaction:

kt = ln([A₀]/[A]),

where, k is the rate constant of the reaction (k = 5.54 x 10⁻¹⁰ year⁻¹).

t is the time of the reaction (t = ??? year).

[A₀] is the initial concentration of (K-40) ([A₀] = 100%).

[A] is the remaining concentration of (K-40) ([A] = 6.25%).

∴ (5.54 x 10⁻¹⁰ year⁻¹)(t) = ln((100%)/( 6.25%))

∴ (5.54 x 10⁻¹⁰ year⁻¹)(t) = 2.77.

∴ t = 2.77/(5.54 x 10⁻¹⁰ year⁻¹) = 5.0 x 10⁹ years.

Answer 2

Answer:

[tex]\boxed{4.99 \times10^{9} \text{ y}}[/tex]

Explanation:

The half-life of potassium-40 (1.248 ×10⁹ y) is the time it takes for half of it to decay.  

After one half-life, half (50 %) of the original amount will remain.  

After a second half-life, half of that amount (25 %) will remain, and so on.  

We can construct a table as follows:  

[tex]\begin{array}{cccc}\textbf{No. of} & &\textbf{Fraction} &\textbf{Percent}\\ \textbf{Half-lives} & \textbf{t/(10$^{9}$ y}) &\textbf{Remaining} &\textbf{Remaining}\\0 & 0 & 1 & 100\\\\1 & 1.248 & \dfrac{1}{2} & 50\\\\2 & 2.496 & \dfrac{1}{4} & 25\\\\3 & 3.744 & \dfrac{1}{8} & 12.5\\\\4 & 4.992 & \dfrac{1}{16} & 6.25\\\\5 & 6.240 & \dfrac{1}{32} & 3.125\\\\\end{array}[/tex]

We see that after four half-lives, ¹/₁₆ or 6.25 % of the original mass remains.

Conversely, if 6.25 % of the sample remains, the age of the sample must be four half-lives.

[tex]\text{Age of rock} = 4 \times 1.248 \times 10^{9}\text{ y}= \boxed{\mathbf{4.99 \times 10^{9}} \textbf{ y}}[/tex]


Related Questions

A. Explain, in terms of particles, why NaCl(s) does not conduct electricity.

Answers

Answer:

Ionic bonds hold charged particles in solid NaCl together, such that they are unable to move or conduct electricity.

Explanation:

Consider an electric current that flows through a conductor: charge moves in a uniform direction from one end of the conductor towards the other.

Thus, there are two conditions for a substance to conduct electricity:

The substance shall contain charged particles, andThese charged particles shall be free to move across the substance.

A conductor of electricity shall meet both requirements.

Now, consider the structure of solid NaCl [tex]\rm NaCl\;(s)[/tex]. NaCl is an ionic compound. It contains an ocean of oppositely charged ions:

Positive [tex]\rm Na^{+}[/tex] ions, andNegative [tex]\rm Cl^{-}[/tex] ions.

Ions carry charge. Thus, solid NaCl contains charged particles and satisfies the first condition.

Inside solid NaCl [tex]\rm NaCl\;(s)[/tex], electrostatic attractions ("ionic bonds") between the oppositely charged ions hold these ions in rigid ionic lattices. These ions are unable to move relative to each other. As a result, they cannot flow through the solid to conduct electricity. Under solid state, NaCl is unable to satisfy the second condition.

As a side note, melting NaCl into a liquid breaks the ionic bonds and free the ions from the lattice. Liquid NaCl is a conductor of electricity.

NaCl(s) does not conduct electricity because, in its solid state, the sodium and chloride ions are held in a fixed lattice structure and cannot move freely.

Electrical conductivity in a substance is dependent on the presence of charged particles that can move freely. In the case of sodium chloride (NaCl), which is an ionic compound, the structure is composed of sodium cations (Na^+) and chloride anions (Cl^-) arranged in a crystalline lattice. When NaCl is in the solid state, the ions are locked into place by strong electrostatic forces of attraction between the oppositely charged ions. These forces hold the ions in a rigid, three-dimensional array, preventing them from moving about freely.

For a material to conduct electricity, it must have mobile charge carriers. In metals, these charge carriers are delocalized electrons that can move throughout the metal. In ionic solutions or molten ionic compounds, the ions themselves are the charge carriers, and they can move when an electric field is applied. However, in solid NaCl, the ions are immobile due to the lattice structure, and thus, there are no free charge carriers to transport electric charge. As a result, solid NaCl does not conduct electricity.

When NaCl is dissolved in water or melted into a liquid, the ions are no longer fixed in place and can move freely. In this state, NaCl does conduct electricity because the ions can act as charge carriers, moving towards the electrodes of opposite charge under an applied electric field

A 250 g sample of water with an initial temperature
of 98.8 Closes 6500 joules of heat. What is the final
temperature of the water?​

Answers

Answer:

.3044

q = mass x specific heat x (Tfinal-Tionitial)

q = -7500. Substitute and solve for Tfinal

Explanation:

Please mark brainliest and have a great day!

What separation technique would most likely be used if a solvent were saved?

Answers

Answer:

Distillation

Explanation:

If the solute is a solid or a liquid with a boiling point at least 30 °C different from that of the solvent, you can use the technique of distillation.

The solvent will boil before the solid or a higher-boiling liquid.

A liquid solute with a lower boiling point than the solvent will boil off first, and then you can distill off the solvent.

Answer:

Distillation

Explanation:

Distillation is a process known long ago and according to some authors was created by the Alchemists at a time where Chemistry was not yet recognized as Science and was closely linked to religious precepts.

Basically the distillation process is a process of physical separation and is used to separate homogeneous mixtures from heating. To separate a solid-liquid type mixture we use simple distillation and to separate liquid-liquid mixtures we use fractional distillation.

What will most likely happen when two bromine atoms bond together?

Answers

They would form a single covalent bond and become Br2.

They would become a covalent bond and become Br2.  

How much energy is generated from freezing 2.5 g water?

Answers

Answer:

Probably, 200 calories.

Explanation:

Answer:

2.5 g x 1 mol/18.02 g x 6.03 kJ/mol

Explanation:

use enthalpy of fusion for both thawing or freezing. The only difference for thawing or freezing would be that when freezing, energy is released (generated) and heat is on the product side, but when thawing , energy is consumed and it is on the reactant side. So for thawing or freezing use 6.03 kJ/mol.

When comparing two solutions with the same volume, you may say that one is dilute and the other is concentrated. What does this mean?

A.
The dilute solution contains more solute than the concentrated solution.
B.
The dilute solution contains less solute than the concentrated solution.
C.
The two solutions are the same.
D.
The concentrated solution contains less solute than the dilute solution.

Answers

Answer:

B. The dilute solution contains less solute than the concentrated solution.

Explanation:

A diluted solution is a solution that has less solute (what is being dissolved) dissolved in the solvent (what is dissolving). A concentrated solution is the opposite, it has more solute than dissolved by the solvent.

A simple example is when you make iced tea (with powder). If you want a strong taste, you add more iced tea powder (solute) to the water (solvent) so it is more concentrated. If you want less, you add more water to dilute it.  

PLEASE HELP WILL GIVE BRAINLIEST TO BEST ANSWER NEED IT FAST! +70 POINTS
A 50.0-mL sample of gas is cooled from 119ºC to 80.0ºC. If the pressure remains constant, what is the final volume of the gas?

Answers

Answer:

45.03 mL.

Explanation:

We can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the gas in atm.

V is the volume of the gas in L.

n is the no. of moles of the gas in mol.

is the general gas constant,

T is the temperature of the gas in K.

If n and P are constant, and have different values of T and V:

(V₁T₂) = (V₂T₁).

V₁ = 50.0 mL, T₁ = 119ºC + 273 = 392 K,

V₂ = ??? mL, ​T₂ = 80ºC + 273 = 353 K.

∴ V₂ = (V₁T₂)/(T₁) = (50.0 mL)(353 K)/(392 K) = 45.03 mL.

To find the final volume of a gas sample when cooled from 119ºC to 80.0ºC at constant pressure, we use Charles's Law, resulting in an approximate final volume of 45.0 mL.

To solve this, we use Charles's Law, which states that for a given mass of gas at constant pressure, the volume is directly proportional to its temperature in Kelvin.

First, convert the temperatures from Celsius to Kelvin:

Final temperature (T₂): 80.0ºC + 273.15 = 353.15 K

Using Charles's Law (V₁/T₁ = V₂/T₂):

Initial volume (V₁) = 50.0 mL

392.15 K / 50.0 mL = 353.15 K / V₂

Rearrange to solve for the final volume (V₂):

V₂ = (50.0 mL × 353.15 K) / 392.15 K

V₂ ≈ 45.0 mL

So, the final volume of the gas is approximately 45.0 mL.

In an AP, sum of four consecutive terms is 28 and their sum of their squares is 276. Find the four numbers.​

Answers

Four Consecutive terms are written as a-3, a-1, a+1,a+3. So

Sum of Terms : 4a=28
a=7

So the terms are 4,6,8,10

Verification : 4^2+6^2+8^2+10^2
= 216

what type of bonding is butane​

Answers

It's worth noting that butane is also referred to as n-butane. ... Based on the diagram, butane is considered to be an alkane. It not only contains single covalent bonds, but also has carbon and hydrogen atoms present in its structure.

what does it mean for something to be dissolved in water

A- it is submerged in water molecules

B-it is stirred in the water molecules

C- it is surrounded by water molecules

D-it has water molecules added to it

Answers

Dissolved in water, has been defined as the solute surrounded by the water molecules. Thus, option C is correct.

Dissolution has been defined as the process of the formation of solution with the addition of solute molecules in the solvent molecules.

What does dissolve in water means?

The dissolution has been achieved with the addition of the solute molecules in the water. The water molecules tend to act the absorbent and surrounds around the solute particles.

There has been a formation of micelle like structure that has been mediated in the dissolution of the compound in water.

Thus, dissolved in water has been defined as the solute surrounded by the water molecules. Thus, option C is correct.

Learn more about dissolution, here:

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Answer:

It is surrounded by water molecules.

Explanation:

Js did it ^v^

a propane torch is lit inside a hot air balloon during preflight preparations to inflate the balloon. which condition of the gas remains constant

Answers

Answer:

The pressure remains constant

Explanation:

this is an example in charles law where as the temperature increases so does the volume.

Answer:

The correct answer is "Pressure".

Explanation:

As the propane torch is ignited inside the hot air balloon, the volume of the gas increases and the temperature of the gas also increases. This causes the density of the gas to decrease, keeping the pressure constant throughout the balloon, regardless of the small amount of gas lost through the balloon hole.

Have a nice day!

A sample of gas is in a rigid cylinder with a movable piston. The pressure of the gas is kept constant. If the Kelvin temperature of the gas is
doubled, the volume of the gas is
O 1.
2
halved
doubled
tripled
unchanged
Submit Retry Answer
Previous

Answers

Answer:

The volume will double, if the temperature of the gas is doubled as temperature and volume are directly proportional.

Answer:

If the Kelvin temperature of the gas is  doubled, the volume of the gas is doubled.

Explanation:

To calculate the final volume of the system, we use the equation given by Charles' Law.

This law states that volume of the gas is directly proportional to the temperature of the gas at constant pressure.

Mathematically,

[tex]\frac{V_1}{T_1}=\frac{V_2}{T_2}[/tex]  (at constnat pressure)

where,

[tex]V_1\text{ and }T_1[/tex] are the initial volume and temperature of the gas.

[tex]V_2\text{ and }T_2[/tex] are the final volume and temperature of the gas.

We are given:

[tex]T_2=2T_1[/tex]

[tex]V_2=?[/tex]

[tex]\frac{V_1}{T_1}=\frac{V_2}{T_2}[/tex]

[tex]\frac{V_1}{T_1}=\frac{V_2}{2T_1}[/tex]

[tex]V_2=2V_1[/tex]

If the Kelvin temperature of the gas is  doubled, the volume of the gas is doubled.

A 20 liter cylinder of helium at a pressure of 150 atm and a temperature of 27°C is used to fill a balloon at 1.00 atm and 37°C. What is the volume of the balloon?
A.
0.14 liters
B.
3000 liters
C.
2900 liters
D.
2400 liters
E.
3100 liters

Answers

Answer:The number of moles will remain the same in the two cases

so we can equate using ideal gas equation which is PV =nRT

V2 = 3100 L

Explanation:

Answer: E.   3100 liters

Explanation:

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is,

[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]

where,

[tex]P_1[/tex] = initial pressure of gas = 150 atm

[tex]P_2[/tex] = final pressure of gas = 1 atm

[tex]V_1[/tex] = initial volume of gas = 20 L

[tex]V_2[/tex] = final volume of gas = ?

[tex]T_1[/tex] = initial temperature of gas = [tex]27^oC=273+27=300K[/tex]

[tex]T_2[/tex] = final temperature of gas = [tex]37^oC=273+37=310K[/tex]

Now put all the given values in the above equation, we get the final pressure of gas.

[tex]\frac{150atm\times 20L}{300K}=\frac{1atm\times V_2}{310K}[/tex]

[tex]V_2=3100L[/tex]

Therefore, the volume of the baloon is 3100 L.

10pt if given the correct answer I will mark you as brainliest
An ordered list of chemical substances is shown.
Chemical Substances

1 Al

2 O2

3 H2O

4 SO2

5 Al2O3



Which substances in the list can be used to write a complete combustion reaction?

A- 1, 2, and 3

B- 1, 4, and 5

C-1, 2, and 5

Answers

Answer:

C

Explanation:

4(Al)+3(O2)==2(Al2O3)

Also, i'm in sixth grade just took a leson on a text book so may be wrong but i'm prety sure it's the correct nswer because x(Al)+y(O2) can not make hydregen for the h2o and for b, al+so2 = al2O3 makes sense but where did the sulfer go?

Answer:

C- 1, 2 and 5

Explanation:

There are many reactions that occur in the world, and one of the more important ones are known as combustion reactions. These reactions always involve the reaction between oxygen and another element/molecule/compound. So automatically, option 2 needs to be correct, so any answer that does not have option 2 in it (B) is incorrect.

Another important factor of combustion reactions is that they give off heat, because they are exothermic reactions, however since there is no indication of energy levels, so the answer in this question cannot be determined through that method.

One important law in all reactions is the conservation of matter, so whatever atoms enter the chemical reaction, have to exit the chemical reaction (no atoms can suddenly appear without having been there originally. For example, if only oxygen and hydrogen enter a reaction, only a product with oxygen and hydrogen can exit the reaction, it is impossible to have a product containing chlorine, if no chlorine was part of the reactants). By this logic, it is impossible to have water (H₂O) as a product, if the reactants are 1 and 2 (Al and O₂), hence option A is incorrect.

The only other option left is option C, and this option is correct because the overall balanced reaction would look like such:

4Al + 3O₂ --> 2Al₂O₃

This reaction obeys the law of conservation of matter, hence, Option C is correct.

What is the correct way to represent 5600 L using scientific notation?

Answers

Answer:

5.6 * 10^3

this is because when thinking about scientific notation you know that you have to include a decimial and how many times you are moving it and whether it is a negative of a positive.

this means that you would take 5600 and you would put the decimal inbetween 5 and 6 because they are significant numbers and then you would have to figure out how many places to the right you need to go inorder to make it 5600

meaning you have to move it three times therefore it becomes

5.6 * 10^3

[tex]5.6*10^{3}[/tex]  is the correct way to represent 5600 L using scientific notation.

What is scientific notation?

In case your decimal quantity is extra than 10, rely on the number of instances of the decimal movements to the left, and upload this variety to the exponent. division: To divide numbers in medical notation, first divide the decimal numbers. Then subtract the exponents of your strength of 10.

How do you change from standard form to clinical notation?

To alternate more than a few from scientific notation to traditional form, circulate the decimal point to the left (if the exponent of ten is a poor variety), or to the right (if the exponent is fine). You must pass the point as often as the exponent indicates. Do no longer write the strength of ten anymore.

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HELP!!!!!!!!!!!!!!!!

Answers

Hyy mate......

Here is your answer ......

➡️⏺️Oxygen⏺️⬅️

1️⃣Name: Oxygen

2️⃣State : non-metal

3️⃣Family:Oxide

4️⃣Protons: 8

Electron:8

Neutron: 8

Hope it will help you...

Thanks for asking....

55. Streptomycin is a derivative of a
a. peptides
b. Carbohydrates
d. Terenes
c.Purines​

Answers

Answer:

I believe it's B.

Explanation:

Hope my answer has helped you!

If the mass of the products measured 120g what would the mass of the reactants
A. 30g
B. 60g
C. 120g
D. 240g

Answers

It has to be 120g because each and every chemical equation has to satisfy the law of conservation of mass, ie sum of mass of products is always equal to the sum of masses of reactants. If reactants=120g, then products=120g

In the following table, all the columns for the element calcium are filled out correctly. Element Electron Structure of Atom Electron Structure of Ion Net Ionic Charge Calcium 1s22s22p63s23p64s2 1s32s22p63s23p64s1 +1 True False

Answers

Answer:

False

Explanation:

Calcium is an element that belongs to the second group on the periodic table. Calcium has a valency of two and would readily loose both electrons in order to achieve stability when forming bonds.

It has 20 electrons.

Calcium would favor ionic bonds when combining with other atoms and by the virtue of this, it would readily transfer its two outermost electrons. This would make its atom mimic that of Argon-18.

The correct information is given below:

Element:                                        Calcium(Ca)

Electron structure of atom:      1S²2S²2P⁶3S²3P⁶4S²

Electron structure of ion:         1S²2S²2P⁶3S²3P⁶

Net ionic charge:                                 +2

Final answer:

The assertion in the table is incorrect. A calcium ion has an electron configuration of 1s22s22p63s23p6 and a net ionic charge of +2, not +1.

Explanation:

The provided electron configuration of the calcium ion is not accurate. The given configuration for the element of calcium (1s22s22p63s23p64s2) represents a neutral calcium atom, not a charged ion. When calcium becomes an ion, it loses two electrons to achieve a stable electron configuration (1s2 2s2 2p6 3s2 3p6), resulting in a net ionic charge of +2 for calcium, not +1. The electron configuration of Calcium ion should therefore be 1s22s22p63s23p6.

So, the assertion that all columns for calcium are filled out correctly in the table is ultimately false. Calcium loses two electrons when it becomes an ion, and therefore has a net ionic charge of +2, not +1.

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which of these best explains the ability of small insects to walk on the surface of still water?

a.) water molecules at the surface experience fewer hydrogen bonds than water molecules within the liquid

b.) the insects’ feet are coated with ionic compounds

c.) water has a very high specific heat

d.) water molecules near the surface produce more buoyant force than water molecules within the liquid

THE ANSWER WAS NOT D.

Answers

Answer:

A.

Explanation:

Smaller insects can walk on water due to surface tension. The force that a smaller insect makes on the water is less than the water and as such the bug will "float."

+if this helped you, please consider marking it the Brainliest in order to help me unlock the next achievement. thank you!

The answer is A!

Apparently there is surface tension between the water and the bugs feet!

What did Bohr’s model of the atom do that Rutherford’s model did not?


It established that electrons move around the nucleus.

It identified the charge of the nucleus.

It established that a large volume of space surrounds the atomic nucleus.

It focused on the location and energy of electrons.

Answers

Answer:

The last option

Explanation:

The Bohr model was an attempt to explain atomic hydrogen's spectrum. This was done by establishing energy levels of separate electron orbits in the atom.Thos model was followed by the Schrödinger model.

Final answer:

Bohr's model built upon Rutherford's by establishing that electrons move around the nucleus in certain paths or 'shells', and focusing more on the location and energy of electrons, a crucial component in understanding atomic structure and behavior.

Explanation:

Bohr’s model added new elements to Rutherford’s model, demonstrating a better understanding of the atom's structure and behavior. One of the key differentiating factors was Bohr's idea that electrons orbit around the nucleus in set paths (or energy levels).

While Rutherford's model did identify the nucleus as positively charged and indicated that a large volume of space surrounds it, it didn't provide a specific path for the electrons' movement. The Bohr model, in contrast, presented the concept of quantized energy levels. According to this model, electrons could occupy specific energy levels and could jump between these levels by absorbing or emitting discrete amounts of energy.

So, to answer your question, Bohr's model, unlike Rutherford’s, established that electrons move around the nucleus in certain paths or 'shells', and it focused more on the location and energy of electrons, which was key to understanding atomic structure and behavior.

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55 L of a gas at 25oC has its temperature increased to 35oC. What is its new volume?

Answers

Answer:

Approximately 56.8 liters.

Assumption: this gas is an ideal gas, and this change in temperature is an isobaric process.

Explanation:

Assume that the gas here acts like an ideal gas. Assume that this process is isobaric (in other words, pressure on the gas stays the same.) By Charles's Law, the volume of an ideal gas is proportional to its absolute temperature when its pressure is constant. In other words

[tex]\displaystyle V_2 = V_1\cdot \frac{T_2}{T_1}[/tex],

where

[tex]V_2[/tex] is the final volume, [tex]V_1[/tex] is the initial volume, [tex]T_2[/tex] is the final temperature in degrees Kelvins.[tex]T_1[/tex] is the initial temperature in degrees Kelvins.

Convert the temperatures to degrees Kelvins:

[tex]T_1 = \rm 25^{\circ}C = (25 + 273.15)\; K = 298.15\; K[/tex].

[tex]T_2 = \rm 35^{\circ}C = (35 + 273.15)\; K = 308.15\; K[/tex].

Apply Charles's Law to find the new volume of this gas:

[tex]\displaystyle V_2 = V_1\cdot \frac{T_2}{T_1} = \rm 55\;L \times \frac{308.15\; K}{298.15\; K} = 56.8\; L[/tex].

What is the formula unit for a compound made from Pb4+ and oxygen?

Answers

Answer : The formula unit of compound will be, [tex]PbO_2[/tex]

Explanation :

As we know that one atom of oxygen contains (2-) charge and one atom of lead contains (4+) charge. So, to balance the of charges of lead, the 2 oxygen atoms combine with the 1 lead atom. Thus, the compound formed will be, [tex]PbO_2[/tex].

That means, when [tex]Pb^{4+}[/tex] combine with oxygen that is, [tex]O^{2-}[/tex], it gives [tex]PbO_2[/tex] by the criss-cross method.

Criss cross method : It is a method of determining the chemical formula.

The formula unit is a shown below.

Answer:

Pb02

Explanation:

guy above was correct i just took my test

Many stereo speaker cables are made of copper wire surrounded by rubber. The electricity travels down the copper portion of the cable while the rubber protects you from being "zapped" by the electricity. Which physical property explains the difference in ability of copper and rubber to transmit electricity?
A.
density
B.
ductility
C.
color
D.
conductivity

Answers

Answer:

d

Explanation:

rubber barely conducts electricity

Answer:

D: Conductivity

Explanation:

Study Island


What is the percentage by mass of silicon (si) in iron aluminum silicate (Fe3Al2(SiO4)3)?

Answers

Answer:

16.93%.

Explanation:

If we have 1.0  mol of Fe₃Al₂(SiO₄)₃:

∴ The mass of 1.0 mol of Fe₃Al₂(SiO₄)₃ = (no. of moles of Fe₃Al₂(SiO₄)₃)(the molecular mass of Fe₃Al₂(SiO₄)₃)

∴ The mass of 1.0 mol of Fe₃Al₂(SiO₄)₃ = (1)(the molecular mass of Fe₃Al₂(SiO₄)₃) = (the molecular mass of Fe₃Al₂(SiO₄)₃).

∴ The mass of 1.0 mol of Fe₃Al₂(SiO₄)₃ = 3(atomic weight of Fe) + 2(atomic weight of Al) + 3(molecular weight of (SiO₄)₃) = 497.7474 g.

The mass of Si in 1.0 mole of Fe₃Al₂(SiO₄)₃ = 3(atomic mass of Si) = 3(28.0855 g/mol) = 84.2565 g.

∵ The mass % of Si = (the mass of Si)/(the mass of Fe₃Al₂(SiO₄)₃) = (84.2565 g)/(497.7474 g) = 16.93%.

Answer:

16.7%

Explanation:


If 10.0 mL of 0.350 M aqueous NaNO3 is mixed with 50.0 mL of 0.170 M aqueous KNO3, what is the molarity of nitrate ion?


A) 0.185 M
B) 0.200 M
C) 0.260 M
D) 0.520 M

Answers

Answer:

0.200 mol/L  

Explanation:

1. Moles of nitrate in first solution

Moles = volume × concentration  

n = 0.0100 L × 0.350 mol/L =0.003 500 mol

2. Moles of nitrate in second solution

n = 0.0500 L × 0.170 mol/L = 0.008 500 mol

3. Total moles of nitrate

n = 0.003 500 + 0.008 500 = 0.012 000 mol

4. Total volume of solution

V = 10.0 + 50.0 = 60.0 mL = 0.0600 L

5. New concentration of nitrate

c = moles/litres

c = 0.012 000 mol/0.0600 L = 0.200 mol/L

The molar concentration of nitrate ion is 0.200 mol/L.

According to Le Chatelier’s principle, what happens when the concentration of reactants is doubled in a chemical reaction that was in equilibrium?
The equilibrium shifts to the right to favor the formation of products.
The equilibrium shifts to the left to favor the formation of reactants.
The equilibrium is unaffected by the increase in concentration.
The equilibrium is lost because the concentrations have been disturbed.

Answers

Answer:

will shift to right

Explanation:

this will result in the formation of more product

According to Le Chatelier’s principle, when the concentration of reactants is doubled the equilibrium shifts to the right to favour the formation of products and the correct option is option 1.

What is Chemical Equilibrium?

Chemical equilibrium refers to the state of a system in which the concentration of the reactant and the concentration of the products do not change with time, and the system does not display any further change in properties.

It is the state of a reversible reaction where the rate of the forward reaction equals the rate of the reverse reaction. While a reaction is in equilibrium the concentration of the reactants and products are constant.

Therefore, According to Le Chatelier’s principle, when the concentration of reactants is doubled the equilibrium shifts to the right to favour the formation of products and the correct option is option 1.

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Which of the following best describes a chain reaction? Select one: a. Neutrons from splitting atoms continue to split other atoms, releasing more neutrons. b. Chemicals released from splitting atoms cause other atoms to split. c. Splitting atoms bump into neighboring atoms, causing them to split. d. A splitting atom causes the atom directly beside it to also split.

Answers

Chain reaction is best described as neutrons from splitting atoms continue to split other atoms, releasing more neutrons.

What is Neutron?

This is referred to as a subatomic particle which has a neutral charge and is produced in preceding fusion of the chain reaction.

The neutron produced initiates the splitting of the atoms which was why option A was chosen in this regard.

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Final answer:

A chain reaction, in the context of nuclear physics, is when neutrons released from a fission event cause other atoms to undergo fission. An example is the fission process of uranium-235, which releases additional neutrons that can trigger further fission, thus leading to an exponentially increasing reaction.

Explanation:

The best description for a chain reaction among the options presented is: 'Neutrons from splitting atoms continue to split other atoms, releasing more neutrons' (Option A). This process refers to a series of nuclear fissions (splitting of a nucleus), where the released neutrons from one fission event cause further fissions. As an example, when undergoing fission, uranium-235 (U-235) produces two medium-sized nuclei and releases two or three neutrons. These neutrons can then cause the fission of other U-235 atoms, which in turn provide more neutrons that can cause more fissions, leading to a nuclear chain reaction.

However, it should be noted that a chain reaction depends on several factors, including how many neutrons are produced in an average fission and how easy it is to induce a particular type of nuclear fission.

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Which pair of elements can be used to determine the age of a fossil that is over one billion years old?

lead, which is radioactive, and uranium, which is stable
carbon, which is radioactive, and nitrogen, which is stable
argon, which is radioactive, and lead, which is stable
potassium, which is radioactive, and argon, which is stable

Answers

Answer: Option (4)

Explanation: The most efficient radioactive method used for the determination of fossil age which is about one billion years old is the Potassium-Argon method (⁴⁰K-⁴⁰Ar).

Potassium-Argon method is generally used to date fossils which are more than 1.2 billion years old as its half life is almost about 1.2 billion years. Potassium is highly radioactive, which converts into Argon and becomes stable.

Uranium and Carbon are also highly radioactive whereas Lead and Nitrogen are stable elements.

¹⁴C-¹⁴N is not an efficient method as it has a half life of only about 5700 years.

Thus the correct answer is option (4).

Answer:

The answer is D) potassium, which is radioactive, and argon, which is stable

Explanation:

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How many grams of oxygen gas are contained in a 15 L sample at 1.02 atm and 28°C? Please show your work.

Answers

Answer:

0.019 g.

Explanation:

Firstly, we need to find the no. of moles of oxygen gas:We can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the gas in atm (P = 1.02 atm).

V is the volume of the gas in L (V = 15.0 L).

n is the no. of moles of the gas in mol (n = ??? mol).

R is the general gas constant (R = 0.0821 L.atm/mol.K),

T is the temperature of the gas in K (T = 28°C + 273 = 301.0 K).

∴ n = PV/RT = (1.02 atm)(15.0 L)/(0.0821 L.atm/mol.K)(301.0 K) = 0.62 mol.

To find the mass of oxygen gas, we have:

no. of moles = mass/molar mass.

∴ mass of oxygen = (no. of moles)(molar mass) = (0.62 mol)(32.0 g/mol) = 0.019 g.

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