Water supplies are treated with chlorine to kill pathogens. Chlorine reacts well with many other chemicals and bacterial cells because it is a strong oxidant. However, Legionella pneumophila can sometimes evade killing by residual chlorine. How does it do this

Answer:

The equation which will tell us how much of A that is mis inmthe water layer after partitioning is: 7 = (17 - x) g / 150 mL ÷ x g /100 mL

Explanation:

A partition coefficient is the ratio of the concentration of a substance in one solvent phase to the concentration in a second solvent phase when the two concentrations are at equilibrium. Usually the two phases are an organic phase and an aqueous phase. Thus, the partition coefficient K, of a compound is the ratio of the compound's concentration in the organic layer compared to the aqueous layer.

K = C₁/C₂ at equilibrium

In the compound A given, CH₂Cl₂ is the organic phase while water is the aqueous phase

Amount of A that is partitioned in between dichloromethane, CH₂Cl₂ and water, H₂O is 17.0 g

Let the amount of A that is dissolved in water be x g

Solubility of A in water given in g/mL = (x / 100) g/ml

Amount of A dissolved in dichloromethane, CH₂Cl₂ = (17 - x) g

Solubility of A in dichloromethane, CH₂Cl₂ given in g/mL = (17 - x/150) g/mL

Since the partition coefficient, K of compound A when comparing its solubility in CH₂Cl₂ to water is 7, that is;

K = [solubility of A in g/ml in CH₂Cl₂] / [solubility of A in g/ml in H2O] = 7

The equation for the amount of A in the water layer is given as follows:

7 = (17 - x) g / 150 mL ÷ x g /100 mL

Solving for x

7 = (17 -x) × 100 / 150x

7 × 150x = (17 - x) × 100

1050x = 1700 - 100x

1150x = 1700

x = 1700/1150

x = 1.48 g

Answer:

11) the difference in heat energies between products and reactants

12) enthalpy change

Explanation:

The heat of reaction is defined as that energy released or absorbed as chemical substances participate in a chemical reaction. It is a term used to denote the change in energy as reactants change into products.

Another name of heat of reaction is enthalpy of reaction. It is a state function since it depends on the initial and final states of the system.

Answer:

Loss of protons and electrons in plutonium 240 decay is not an example of an everyday reaction

Answer:

Mass number (A) is the number of nucleons (proton and neutron) present in a atom.

Explanation:

electrons don't cout since they are thousandth's of the mass of protons or neutrons

Answer :

Answer:

Examples of isotones include carbon-12, nitrogen-13 and oxygen-14. These atoms all have six neutrons and six, seven and eight protons respectively. A mnemonic that can be used to differentiate isotones from isotopes and isobars is as follows: same Z (number of protons) = isotopes.

An OH group attached to a hydrocarbon is called an alkyl group whereas hydroxide is a polyatomic ion with a charge of -1.

OH group is also called hydroxyl group. Alcohol is a type of organic compound that is characterized by one or more hydroxyl (―OH) groups attached to a carbon atom of an hydrocarbon chain so we can conclude that an OH group attached to a hydrocarbon is called an alkyl group whereas hydroxide is a polyatomic ion with a charge of -1.

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With the help of hess's law:

ΔHf(MnO)=−248.9 kJ−12(272.0) kJ=−384.9 kJ(per mole) Δ H f ( M n O ) = − 248.9 k J − 1 2 ( 272.0 ) k J = − 384.9 k J ( p e r m o l e )

Hess's law of constant heat summation, also known simply as Hess' law, is a relationship in physical chemistry named after Germain Hess, a Swiss-born Russian chemist and physician who published it in 1840.

Moreover, hess's Law of Constant Heat Summation (or just Hess's Law) states that regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes.

Therefore, hess' law is based on the state function character of enthalpy and the first law of thermodynamics. Energy (enthalpy) of a system (molecule) is a state function.

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Answer:

i thing its b

Explanation:

The acid dissociation constant (Ka) is a measure of the strength of an acid in solution. In HNO₃ (nitric acid), the given Ka value is 4.0 x 10⁴. It represents the equilibrium constant for the dissociation reaction of an acid in water. Therefore, option B is correct.

The dissociation constant often denoted as Kd, is a measure of the strength of the interaction between a ligand and a receptor or between a substrate and an enzyme.

A high Ka value indicates a strong acid, while a low Ka value indicates a weak acid. In this case, the Ka value of 4.0 x 10⁴ for HNO₃ is relatively high.

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Answer:

c.

Explanation:

From the given information:

Critical fracture toughness [tex]K_{IC}[/tex] = 150 MPa.[tex]m ^{1/2}[/tex]

yield strength [tex]\sigma[/tex] = 1500 MPa

surface crack size [tex]a_c[/tex] = ???

The formula for the fracture toughness is can be expressed as:

[tex]K_{IC}= \sigma \sqrt{\pi a_c}[/tex]

replacing our values to solve for the surface crack size, we have:

[tex]150= 1500 \sqrt{\pi a_c}[/tex]

[tex]\dfrac{150}{ 1500} = \sqrt{\pi a_c}[/tex]

[tex]\dfrac{0.1}{1.77} = \sqrt{ a_c}[/tex]

[tex]a_c[/tex] = 0.0564²

[tex]a_c[/tex] = 0.0032 m

[tex]a_c[/tex] = 0.32 cm

Answer:

Ammonium hydroxide, NH₄OH

Magnesium hydroxide, Mg(OH)₂

Sodium hydroxide, NaOH

Lithium hydroxide, LiOH

Explanation:

A base is a substance which neutralizes acids to produce salt and water. Bases are hydroxide or oxides of metals. Bases may be soluble or insoluble in water. Bases generally have a bitter taste and turn red litmus paper or indicator red.

Alkalis are bases which are soluble in water. They form the hydroxide of the alkali metals or alkaline earth metals in solution and they ionize to produce hydroxide ions. They are slippery to touch and turn red litmus blue being bases.

Therefore, all alkalis are bases but not all bases are alkalis. Insoluble bases are not alkalis.

From the given chemical compounds the alkalis present in the list are:

Ammonium hydroxide, NH₄OH; since it is soluble in water and produces hydroxide ions

Magnesium hydroxide, Mg(OH)₂; since it is slightly soluble in water and produces hydroxide ions

Sodium hydroxide, NaOH; since it is soluble in water and produces hydroxide ions

Lithium hydroxide, LiOH; since it is soluble in water and produces hydroxide ions

CuO(copper oxide) is a base but not an alkali as it does not produce hydroxide ions.

Zn(OH)2 (zinc hydroxide) is amphoteric and is insoluble

MgO(magnesium oxide) is a base but not an alkali as it does not produce hydroxide ions.

Na2O(sodium oxide) is a base but not an alkali as it does not produce hydroxide ions.

CoO(cobalt oxide) is a base but not an alkali as it does not produce hydroxide ions.

Answer:

The answer is below

Explanation:

Yes, there are multiple combinations.

Firstly, a solvent or soap combination could be used as a polar solvent with soap. In this way, the nonpolar region of the soap molecules would mix directly with the stain while the solvent would surround the soap-stain micelle.

Secondly, another method or way is to have a combination of a nonpolar solvent with no soap. In this method, however, it is the solvent that would mix directly with the stain.

Answer:

If 7.9 moles of C₅H₁₂ reacts with excess O₂, 39.5 moles of CO₂ will be produced.

Explanation:

The balanced reaction is:

C₅H₁₂ + 8 O₂ → 5 CO₂ + 6 H₂O

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Then you can apply the following rule of three: if by stoichiometry 1 mole of C₅H₁₂ produces 5 moles of CO₂, then 7.9 moles of C₅H₁₂ will produce how many moles of CO₂?

[tex]amount of moles of CO_{2} =\frac{7.9 moles of C_{5}H_{12}*5 moles of CO_{2} }{1 mole of C_{5}H_{12} }[/tex]

amount of moles of CO₂= 39.5 moles

If 7.9 moles of C₅H₁₂ reacts with excess O₂, 39.5 moles of CO₂ will be produced.

Answer: The value for rate constant for a reaction is [tex]4.81\times 10^{-4} s^{-1}[/tex]

Explanation:

The integrated rate law equation for first-order kinetics:

[tex]k=\frac{2.303}{t}\log \frac{a}{a-x}[/tex] ......(1)

Let the initial concentration of reactant be 100 g

Given values:

a = initial concentration of reactant = 100 g

a - x = concentration of reactant left after time 't' = 25 % of a = 25 g

t = time period = 48 min = 2880 s       (Conversion factor: 1 min = 60 s)

Putting values in equation 1:

[tex]k=\frac{2.303}{2880s}\log (\frac{100}{25})\\\\k=4.81\times 10^{-4} s^{-1}[/tex]

Hence, the value for rate constant for a reaction is [tex]4.81\times 10^{-4} s^{-1}[/tex]

Answer:

A chemistry student must write down in her lab notebook the concentration of a solution of sodium thiosulfate. The concentration of a solution equals the mass of what's dissolved divided by the total volume of the solution.

Explanation:

The concentration of a solution can be measured in terms of molarity.

The molarity of a solution can be defined as the number of moles of solute present in the total volume of the solution.

The number of moles of solute is the ratio of mass of solute to molar mass of solute.

Hence,

[tex]Molarity=\frac{mass of solute}{molar mass of solute} * \frac{1}{volume of solution in L.}[/tex]

AAnswer:A

Explanation:

If the salt water is heated, the water turns into steam and the salt remains because the water has a lower boiling point than the salt.

The  following points can be considered:

The process involved when salt water is heated:

Therefore, the answer is water has a lower boiling point than salt.

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Answer:

a, d and e. are true.

Explanation:

The reaction that occurs is:

Na2CO3(aq) + CaCl2(aq) → CaCO3(s) + 2NaCl

In ideal conditions, the percent yield of the reaction must be 100%. All explanations about why the student could not collect all precipitate are right:

a. The combined reactants were not stirred before filtering the precipitate. Not stirring could not promote all the reaction. TRUE.

b. The student did not completely dry the precipitate before weighing it. If the student don't dry the precipitate, the mass of precipitate must be higher producing a percent yield > 100%. FALSE.

c. The precipitate was not washed prior to drying. Produce more mass. FALSE.

d. A rubber policeman was not used to scrape precipitate from the beaker. If the student doesn't collect all the precipitate the percent yield could be < 100%.. TRUE.

e. The filter paper was not wetted with water prior to filtering the precipitate. TRUE. If you don't wet the filter paper you can lose a part of precipitate from the walls of this one.

Formula is (CH3)2CHCH2C(CH3)3 and the name is 2,2,4-trimethylpentane

Answer:

1.62 g

Explanation:

Given that:

Concentration of HCN = 0.119 M

Assuming the ka 4.00 × 10⁻¹⁰

The pKa of  HCN (hydrocyanic acid)  = -log (Ka)

= - log ( 4.00 × 10⁻¹⁰)

= 9.398

pH of buffer = 8.809

Using Henderson Hasselbach equation:

[tex]pH = pKa + log \dfrac{[conjugate\ base ]}{acid}[/tex]

[tex]pH = pKa + log \dfrac{[CN^-]}{[HCN]}[/tex]

[tex]8.809 = 9.398 +log \dfrac{[CN^-]}{[HCN]}[/tex]

[tex]log \dfrac{[CN^-]}{[HCN]}= 8.809 - 9.398[/tex]

[tex]log \dfrac{[CN^-]}{[HCN]}= -0.589[/tex]

[tex]\dfrac{[CN^-]}{[HCN]}= 0.2576[/tex]

[CN^-] = 0.2576[HCN]

[CN^-] = 0.2756 (0.119) L

[CN^-] = 0.033 M

∴

The amount of NaCN (sodium cyanide) is calculated as follows:

[tex]= 1.00 L \times \dfrac{0.033 \ mol \ NacN }{1 \ L } \times \dfrac{49.01 \ g}{1 \ mol \ of \ NacN}[/tex]

= 1.62 g

Answer:

Hello There!!

Explanation:

The atom is still 24Na.

hope this helps,have a great day!!

~Pinky~

Answer:

my define it will be turst me is c

Answer:

[tex]k_1=0.107s^{-1} \\\\k_2=0.711M^{-1}s^{-1}[/tex]

Explanation:

Hello there!

In this case, according to the given information and the attached picture in which we can see the units of the rate constant, it turns out possible for us to realize the two called rate laws are:

[tex]r=k[A]\\\\r=k[A]^2[/tex]

The former is first-order and the latter second-order; in such a way, we solve for the rate constant in both cases to obtain the following:

[tex]k=\frac{r}{[A]}=\frac{1.6x10^{-2}M/s}{0.15M}=0.107s^{-1} \\\\k=\frac{r}{[A]^2}=\frac{1.6x10^{-2}M/s}{(0.15M)^2}=0.711M^{-1}s^{-1}[/tex]

Regards!

Fabric A is likely to be a material that has a moderate tendency to gain electrons when in contact with other materials and is lower in the electrostatic series than ebonite but higher than wood.

The electrostatic series is a list of materials ranked in order of their tendency to gain or lose electrons when in contact with another material.

Materials higher in the series tend to lose electrons more readily and become positively charged, while materials lower in the series tend to gain electrons more readily and become negatively charged.

Ebonite is a synthetic polymer that is known to become negatively charged when rubbed, and it is typically placed near the top of the electrostatic series.

Wood, on the other hand, is a poor conductor of electricity and does not readily become charged when rubbed. Based on these facts, we can infer that Fabric A is lower in the electrostatic series than ebonite, but higher than wood.

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Answer:

For A: The wavelength of the light is [tex]1.052\times 10^4nm[/tex]

For B: The number of photons per joule is [tex]2.063\times 10^{18}[/tex]

For C: The binding energy of a metal is 1.197 eV.

Explanation:

The equation used to calculate the energy of a photon follows:

[tex]E=\frac{hc}{\lambda}[/tex]            ......(1)

where,

E = energy of a photon

h = Planck's constant = [tex]6.626\times 10^{-34}J.s[/tex]

c = speed of light = [tex]3\times 10^{8}m/s[/tex]

[tex]\lambda[/tex] = wavelength

Given values:

E = [tex]1.89\times 10^{-20}J[/tex]

Putting values in equation 1, we get:

[tex]\lambda=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{1.89\times 10^{-20}J}\\\\\lambda=1.052\times 10^{-5}m[/tex]

Converting the wavelength into nanometers, the conversion factor used is:

[tex]1m=10^9nm[/tex]

So, [tex]\lambda=1.052\times 10^{-5}m\times \frac{10^9nm}{1m}=1.052\times 10^4nm[/tex]

Hence, the wavelength of the light is [tex]1.052\times 10^4nm[/tex]

Given values:

[tex]\lambda=410nm=410\times 10^{-9}m[/tex]

Putting values in equation 1, we get:

[tex]E=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{410\times 10^{-9}m}\\\\E=4.848\times 10^{-19}J[/tex]

To calculate the number of photons, we use the equation:

[tex]\text{Number of photons}=\frac{\text{Total energy}}{\text{Energy of a photon}}[/tex]

Total energy = 1 J

Energy of a photon = [tex]4.848\times 10^{-19}J[/tex]

Putting values in the above equation:

[tex]\text{Number of photons}=\frac{1J}{4.848\times 10^{-19}J}\\\\\text{Number of photons}=2.063\times 10^{18}[/tex]

Hence, the number of photons per joule is [tex]2.063\times 10^{18}[/tex]

To calculate the binding energy of a metal, we use the equation:

[tex]E=K+B[/tex]             .....(2)

E = Total energy

K = Kinetic energy of a photon

B = Binding energy of metal

Converting the energy from joules to eV, the conversion factor used is:

[tex]1eV=1.602\times 10^{-19}J[/tex]

Using the above conversion factor:

[tex]K=2.93\times 10^{-19}J=1.829eV\\\\E=4.848\times 10^{-19}J=3.026eV[/tex]

Putting values in equation 2:

[tex]B=(3.026-1.829)eV=1.197eV[/tex]

Hence, the binding energy of a metal is 1.197 eV.

Answer:

b

Explanation:

Answer:

B

Explanation:

Answer:

compounds are elements include an element and a compound

Explanation:

elements in the decomposition reaction is the substance that cannot be separated into simpler substances. Compounds, technically act as a reactant in the decomposition reaction, but since the reaction breakdown one substance into two or more, sometimes it exists in the product

Answer:

c

no need to thank me okay

Answer:

2.42x10⁹ years is the age of the rock

Explanation:

The decay of an isotope follows the equation:

Ln[A] = -kt + Ln[A]₀

Where [A] is amount of isotope after time t, k is decay constant and [A]₀ is the initial amount of the isotope

To find decay constant from half-life:

k = ln2 / half-life

k = ln2 / 1.26x10⁹years

k = 5.501x10⁻¹⁰ years⁻¹

As in the reaction, K-40 produce Ar-40:

[A] = 0.359mmol

[A]₀ = 0.359mmol + 1.000mmol = 1.359mmol

Replacing:

Ln[0.359mmol] = -5.501x10⁻¹⁰ years⁻¹t + Ln[1.359mmol]

-1.3312 = -5.501x10⁻¹⁰ years⁻¹t

t = 2.42x10⁹ years is the age of the rock