Write the complete balanced equation for the following reaction: Na2SO4 + Pb(NO3)2 -->NaNO3 + PbSO4

After three half-lives, 12.5% of the original radioactive parent isotope will remain.

To determine the remaining amount of a radioactive parent isotope after a given number of half-lives, you need to understand the concept of radioactive decay.

A radioactive isotope undergoes decay, reducing its quantity over a set period known as a half-life.

Each half-life represents the time it takes for half of the parent isotope to decay into a daughter isotope.

Explanation and Calculation:

1. Concept of Half-Life:

- A half-life is the time required for half of the radioactive parent isotope to decay.

2. Formula for Remaining Fraction:

- The fraction of the parent isotope remaining after n half-lives can be calculated using the formula:

[tex]\[ \left(\frac{1}{2}\right)^n \][/tex]

- Here, n is the number of half-lives.

3. Calculation for Three Half-Lives:

[tex]\text{After 1 half-life:} \\\\\left(\frac{1}{2}\right)^1 = \frac{1}{2} = 0.5 \text{ (50\% remains)}\\\text{After 2 half-lives:} \\\\\left(\frac{1}{2}\right)^2 = \frac{1}{4} = 0.25 \text{ (25\% remains)}\\\text{After 3 half-lives:} \\\\\left(\frac{1}{2}\right)^3 = \frac{1}{8} = 0.125 \text{ (12.5\% remains)}[/tex]

Conclusion:

Thus, after three half-lives, only 12.5% of the original parent isotope remains. This is calculated using the formula [tex]\(\left(\frac{1}{2}\right)^n\)[/tex], where n is the number of half-lives.

Answer:

protons in the atom

Explanation:

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The number of molecules resulting from a chemical reaction depends on the balanced chemical equation, which is not provided for the ethanol combustion. We would need this to determine the exact quantities of CO2, H2O, and O2 produced from the reaction involving ethanol.

To determine the number of molecules present after a chemical reaction has gone to completion, we use the balanced chemical equations. However, the initial question does not provide a complete balanced equation for the reactions involving CO2, H2O, C2H5OH (ethanol), and O2 (oxygen). We are provided information about the combustion of methane and the reaction of propane but not the specific reaction for ethanol, which is necessary to determine the exact number of molecules produced in its combustion.

Given the example of the propane combustion, which yields 3 moles of CO2 and 4 moles of H2O from 0.75 mol of propane, we can extend this stoichiometric ratio to determine the number of molecules. The number of molecules produced from the combustion of a known quantity of another substance, like ethanol, would depend on its stoichiometry. Without the balanced equation for ethanol combustion, we cannot calculate the exact quantities of CO2, H2O, and O2 produced. Therefore, the student should provide the complete balanced chemical equation or clarify if the question is about a different reaction than the ones provided.

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Answer:

The emission of free carriers or electrons taking place when light falls into a substance is termed as the photoelectric effect. On the basis of the Rutherford model, the light of any energy should possess the tendency to cause the electrons to leave the atom and get emitted.  

The energy obtained from the emitted electrons should be associated with the intensity of the light. However, the energy of the electron is in the real sense only associated with the energy of the light.  

Answer: Option (c) is the correct answer.

Explanation:

It is necessary to take precautions while performing an experiment in a laboratory. This is because safety measures in the laboratory can prevent any serious injury.

For example, when accidentally an acid spills on Celia's hand then it is important to inform the teacher about it while Celia washes her arm with soap and water.

Also, when doing an experiment or dealing with acids the we should be wearing lab coat, safety goggles, closed shoes and safety gloves.

Thus, we can conclude that out of the given options, Lee should tell the teacher while Celia washes her arm with soap and water, this should be done next.

When reporting the mass of the NaCl sample, consider the number of significant figures. The precision of the measurement equipment determines the appropriate number of significant figures to report.

When reporting the measurement of the mass of the NaCl sample, you should consider the significant figures. Significant figures are the digits in a number that carry meaning and contribute to its precision. In general, you should report your measurement to the same number of significant figures as the least precise measurement involved in the calculation.

In the given question, there is no specific information provided about the NaCl sample and the precision of the measurement. Therefore, it is not possible to determine the accurate number of significant figures to report. However, it is important to determine the precision of the equipment used to measure the mass and report the measurement accordingly.

Jon and Katarina use the same method for completing a lab report because they are both using scientific inquiry to conduct their experiments.

Jon and Katarina use the same method for completing a lab report because they are both using scientific inquiry to conduct their experiments. The scientific method is a process that scientists follow to gather information, form hypotheses, test their hypotheses through experiments, and draw conclusions based on their results. It is a systematic and organized approach that can be applied to various scientific disciplines, including chemistry and geology.

The solution with a higher concentration of hydroxide ions (oh-) than hydrogen ions (h+) are base solutions or solutions which are the basic  option B is correct.

A solution which is basic in nature in  aqueous solution  they contain   more OH - ions concentration than that of H + ions concentration. that is they are, in  aqueous solution with a pH greater than 7.

Basic solutions contain ions, with some  conducted  electricity, and it turn red litmus paper blue, and slippery while touching.

They are mostly used in the manufacturing of soaps, toothpaste, paper and rayon as they do not react with skin due to basic in nature.

Basic substances react to aqueous solutions by accepting or gaining of  protons, giving away or releasing the  electrons, or releasing and make free hydroxide ions.

Therefore, they are basic solutions. option B is correct

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The given question is incomplete therefore, the complete question is

a solution with a higher concentration of hydroxide ions (oh-) than hydrogen ions (h+)

A.acid

B. base

C.neutral

Final answer:

A polar covalent bond is a type of covalent bond with unequal sharing of electrons due to a difference in electronegativity between the bonded atoms, leading to a partial negative and positive charge on the atoms.

Explanation:

The best definition of a polar covalent bond is a type of covalent bond in which the electrons are shared unequally between the bonded atoms. This disparity in sharing occurs because the atoms involved have different electronegativities - a measure of how strongly an atom attracts electrons in a bond.

When the difference in electronegativities between the two atoms falls between 0.4 and 1.7, the electrons are not shared equally, leading to a polar bond. One atom attracts the shared electrons more strongly, giving it a partial negative charge, while the other atom acquires a partial positive charge, creating a dipole.

In contrast, a nonpolar covalent bond occurs when the electronegativity difference is less than 0.4, resulting in equal sharing of electrons and no dipole. On the opposite end of the spectrum, if the difference in electronegativity is greater than 1.7, it may lead to an ionic bond, where electrons are transferred rather than shared.

A polar covalent bond is a type of covalent bond where the electrons are shared unequally between the bonded atoms.

This happens because the atoms involved have different electronegativities, meaning one atom attracts the shared electrons more strongly than the other. Typically, if the difference in electronegativity between the atoms is between 0.4 and 1.7, the bond is considered polar covalent.

Due to this unequal sharing, the molecule has regions with partial positive and partial negative charges, leading to an imbalance in electron distribution. These partial charges create a dipole moment within the molecule, making it polar.

Answer : The correct option is, [tex]6.0\times 10^{-5}M[/tex]

Explanation :  Given,

pOH = 4.22

pOH : It is defined as the negative logarithm of hydroxide ion concentration.

Now we have to calculate the [tex]OH^-[/tex] concentration.

Formula used :

[tex]pOH=-\log [OH^-][/tex]

Now put all the given values in this formula, we get the concentration of hydroxide ion.

[tex]4.22=-\log [OH^-][/tex]

[tex][OH^-]=6.0\times 10^{-5}M[/tex]

Therefore, the [tex]OH^-[/tex] concentration is, [tex]6.0\times 10^{-5}M[/tex]

Hydrochloric acid (HCl) is a strong acid that fully dissociates in an aqueous solution, meaning it releases all of its hydrogen ions, making the solution highly acidic. Unlike weak acids, it does not create a buffered solution when reacted with a strong base. Adding HCl to a solution typically lowers the pH level due to the increase in hydrogen ion concentration.

A strong acid like HCl (hydrochloric acid) fully dissociates in an aqueous solution. This essentially means that virtually every HCl molecule that dissolves in water will undergo a reaction; donating H* (hydrogen ions) and becoming highly acidic. Acids that react completely in this way are known as strong acids.

Conversely, a weak acid does not fully dissociate in solution and some of its hydrogen ions remain bonded within the compound. For instance, acetic acid, the main component in vinegar is a weak acid.

When HCl reacts with a strong base, it can produce a salt and water, but it does not create a buffered solution. It's also important to note that adding a strong acid to an aqueous solution usually lowers (not raises) the pH due to the increase in hydrogen ion concentration.

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Answer:

522.2kJ

Explanation:

Hello,

In this case, based on the given conversion data, we apply the following proportional factor to obtain the corresponding energy in kJ:

[tex]125cal*\frac{4.18kJ}{1cal}=522.2kJ[/tex]

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The volume of solid ice is greater than the volume of water. In winter in the absence of heat water in the pipe freezes, as ice takes greater space to fit in than water, the pipe burst in winter in the absence of heating.

Freezing of water is an exothermic process (heat is released by the system into the surrounding) where as melting of ice is an endothermic process (heat is absorbed by the system from the surrounding). If the heat was on it would prevent ice formation in the pipes.

The water pipes burst due to the expansion of water in them.

Water behaves in an anomalous manner. While most substances expand when heated and contract when cooled, water begins to expand at 4°C.

As a result of this, solid water is less dense than liquid water because it has more volume than liquid water.

Since solid water has more volume compared to liquid water, the pipes may no longer be able to contain the expanding water which has turned to ice leading to the bursting of the water pipes.

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Answer: The molar mass of the gas is 2.02 grams.

Explanation:

We are given:

Density of gas = 0.0902 g/L

At STP conditions:

1 mole of gas occupies 22.4 L of volume

And 1 mole of a substance is known as the molecular mass or molar mass of that substance.

To calculate the mass of gas, we use the equation:

[tex]\text{Density of gas}=\frac{\text{Mass of gas}}{\text{Volume of gas}}[/tex]

Putting values in above equation, we get:

[tex]0.0902g/L=\frac{\text{Mass of gas}}{22.4L}\\\\\text{Mass of gas}=2.02g[/tex]

Hence, the molar mass of the gas is 2.02 grams.

The molar mass of an ideal gas can be calculated by multiplying its density (given as 0.0902 g/L) by the molar volume of gas at STP (which is 22.4 L/mol). This gives us a molar mass of approximately 2.02 g/mol.

For an ideal gas at Standard Temperature and Pressure (STP), which is 0°C (273.15K) and 1 atm, one mole of the gas occupies a volume of 22.4 L. This is a well-known fact. Now, molar mass is the mass of one mole of a substance. You're given the density of the gas (0.0902 g/L).

We can use this known volume of a mole of gas at STP and the given density to find the molar mass. The formula to do that would be: Molar mass = Density x Molar volume.

Substitute the values into this equation:

Molar mass = 0.0902 g/L x 22.4 L/mol

Molar mass = 2.02 g/mol

Therefore, the molar mass of the gas is approximately 2.02 g/mol.

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There are [tex]6.12 \times 10^{23}[/tex] atoms of oxygen in 30.5 grams of glucose. There is a little over one mole of oxygen in the given mass of glucose, therefore the number of O atoms should be a little over Avogadro's number.

FURTHER EXPLANATION

To get the number of atoms present in 30.5 g of glucose the following steps must be done:

STEP 1: Convert 30.5 g glucose to moles by dividing the given mass by the formula mass (molar mass).

The molar mass of glucose is 180.156 g/mol obtained as follows:

[tex]formula \ mass \ C_6H_{12}O_6 \ = (6)(12.011) \ + \ (12)(1.008) \ + \ (6)(15.999)\\\boxed {formula \ mass \ C_6H_{12}O_6 \ = 180.156}[/tex]

The mass of 1 mol of glucose is equal t its formula mass in g.

Next, set up the equation below to convert the mass of glucose to moles of glucose.

[tex]moles \ C_6H_{12}O_6 \ = 30.5 \ g (\frac{1 \ mol}{180.156 \ g})\\\\\boxed { moles \ C_6H_{12}O_6 \ = 0.1693 \ mol}[/tex]

STEP 2: Determine how many  moles of oxygen are in the given moles of glucose. The subscripts of the elements in the chemical formula will give the mole ratio: 1 mole of glucose has 6 moles of oxygen atoms.

[tex]moles \ of \ O \ = 0.1693 \ mol \ C_6H_{12}O_6 \ (\frac{6 \ mol \ O}{1 \ mol \ C_6H_{12}O_6})\\\boxed {moles \ of \ O \ = 1.0158 \ mol}[/tex]

STEP 3: Use Avogadro's number to calculate the number of atoms of O

1 mol of O has [tex]6.022 \times 10^{23}[/tex] O atoms

[tex]no. \ of \ O \ atoms \ = 1.0158 \ mol \ O \ \times \frac{6.022 \times 10^{23} \ atoms \ O}{1 \ mol \ O} \\\boxed {no. \ of \ O \ \ atoms \ = 6.117 \times 10^{23} \ atoms}[/tex]

Since the given, 30.5 g has 3 significant figures, the final answer must also have 3 significant figures. Therefore,

[tex]\boxed {atoms \ of \ O \ = 6.12 \times 10^{23} \ atoms}}[/tex]

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Keywords: moles, Avogadro's number

Answer:508

Explanation:

I saw from another post or actually 507.8

Answer:

B) Nitrogen monoxide gas plus hydrogen gas yields ammonia gas plus water vapor

Explanation:

The given reaction is:

[tex]2NO(g) + 5H_{2}(g)\rightarrow 2NH_{3}(g)+ 2H_{2}O(g)[/tex]

Here the chemical names of the reactants are:

NO = nitric oxide or nitrogen monoxide in gas phase

H2 = hydrogen gas

NH3 = ammonia in gas phase

H2O = water in gas phase i.e. vapor

Therefore the reaction can be expressed in words as:

Nitrogen monoxide gas plus hydrogen gas yields ammonia gas plus water vapor

To solve this problem, first we assume the volume is purely additive. The density of the mixture can then be calculated by the summation of mass fraction of each component divided by its individual density:

1 / ρ mixture = (x NH3 / ρ NH3) + (x H2O / ρ H2O)                        ---> 1

Calculating for mass fraction of NH3:

x NH3 = 15 g / (15 g + 250 g)

x NH3 = 0.0566

Therefore the mass fraction of water is:

x H2O = 1 – x NH3 = 1 – 0.0566

x H2O = 0.9434

Assuming that the density of water is 1 g / mL and substituting the known values back to equation 1:

1 / 0.974 g / mL = [0.0566 / (ρ NH3)] + [0.9434 / (1 g / mL)]

ρ NH3 = 0.680 g / mL

Given the density of NH3, now we can calculate for the volume of NH3:

V NH3 = 15 g / 0.680 g / mL

V NH3 = 22.07 mL

The number of moles NH3 is: (molar mass NH3 is 17.03 g / mol)

n NH3 = 15 g / 17.03 g / mol

n NH3 = 0.881 mol

Therefore the molarity of NH3 in the solution is:

Molarity = 0.881 mol / [(22.07 mL  + 250 mL) * (1L / 1000 mL)

M = 3.238 mol/L = 3.24 M

To find the molarity of the NH3 solution, divide the moles of NH3 by the volume of the solution in liters.

To find the molarity of the NH3 solution, we need to first calculate the moles of NH3. We can do this by dividing the mass of NH3 (15.0 g) by its molar mass (17.03 g/mol) to get 0.881 mol. Next, we need to calculate the volume of the solution. Because density is mass divided by volume, we can rearrange the equation to solve for volume, which is mass divided by density. Substituting in the given values, we get 250.0 g / 0.974 g/ml = 256.62 ml. Since 1 ml is equal to 0.001 L, the volume of the solution is 0.25662 L. Finally, we can calculate the molarity by dividing the number of moles of solute (NH3) by the volume of the solution in liters. Substituting the values, we get 0.881 mol / 0.25662 L = 3.43 M.

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We balance the given redox reaction using the half-reaction method. First, we write the half-reactions, balance atoms other than H and O, balance O by adding H2O, balance H by adding H+ ions, and ensure electrical neutrality by adding electrons. The result is the balanced reaction: 2Ag + clo2- + 2H2O → 2Ag + clo4- + 4H+.

The task is to balance a redox reaction wherein clo2– is oxidized to clo4– and Ag is reduced to Ag in an acidic solution. We do this by employing a method known as the half-reaction method which involves the following steps:

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