please help! BRAINLIEST to right answer

The given question is not complete, the complete question is:

A chemistry student needs 5.00 g of thiophene for an experiment. She has available 0.50 kg of a 28.7% w/w solution of thiophene in benzene, Calculate the mass of solution the student should use. If there's not enough solution, press the "No solution" button Be sure your answer has the correct number of significant digits. X

Answer:

The correct answer is 17.4 grams.

Explanation:

As mentioned in the given question, 28.7 percent w/w solution thiophene in benzene shows that,  

(wt. of thiophene / wt. of thiopene + benzene) * 100 = 28.7

0.50 kg of the solution indicates that it is 500 grams of the solution.  

Therefore, the amount of thiophene found in the 500 grams of the solution is,  

500 g * 28.7 / 100 = 143.5 gm

Thus, 143.5 grams of thiophene is found 500 grams of the solution.  

Now, 1 gram of thiophene will be in 500/143.5 of solution.  

Therefore, 5 grams of thiophene will be in 500/143.5 * 5 g of the solution = 17.42 grams of the solution.  

Hence, the mass of the solution to be used by the student in the given case will be 17.4 grams.  

Answer:

Dissociated state is the predominant one

Explanation:

When a molecule with pKa of 4.52 is in an aqueous solution at pH = 4.0, follows the H-H equation, thus:

pH = pKa + log₁₀ [A⁻] / [HA]

Where [A⁻] is the dissociated state and [HA] represents the protonated state

Replacing:

4.0 = 5.2 + log₁₀ [A⁻] / [HA]

-1.2 = log₁₀ [A⁻] / [HA]

0.063 =  [A⁻] / [HA]

[HA]  = 16 [A⁻]

That means you have 16 times more [HA] than [A⁻] and the dissociated state is the predominant one

Answer:

1/2 of the Pi

Explanation:

PV = nRT

we are going to assume the only things changing are pressure and number of mols, so we change the formula and substitute the variables to make it what we are looking for

[tex]\frac{Pi}{ni} = \frac{Pf}{nf}[/tex]

then we will assume Pi as 1 as it is not given, so we can state it easier

[tex]\frac{1atm}{10mol} = \frac{xatm}{5mol}[/tex]

then either cross multiply or just work it out to be

[tex]\frac{1}{2}[/tex] which we can say as "half of the initial pressure" as no number is given for initial pressure

Answer:

1.3×10⁻³ M

Explanation:

Hello,

In this case, given the dissociation reaction of acetic acid:

[tex]CH_3CO_2H(aq) + H_2O(l) \rightleftharpoons H_3O^+(aq) + CH_3CO_2^-(aq)[/tex]

We can write the law of mass action for it:

[tex]Ka=\frac{[H_3O^+][CH_3CO_2^-]}{[CH_3CO_2H]}[/tex]

Of course, excluding the water as heterogeneous substances are not included. Then, in terms of the change [tex]x[/tex] due to the dissociation extent, we are able to rewrite it as shown below:

[tex]1.8x10^{-5}=\frac{x*x}{0.100-x}[/tex]

Thus, via the quadratic equation or solve, we obtain the following solutions:

[tex]x_1=-0.00135M\\x_2=0.00133M[/tex]

Obviously, the solution is 0.00133M which match with the hydronium concentration, thus, answer is: 1.3×10⁻³ M in scientific notation.

Regards.

Answer:

1.3×10^-3 M

Explanation:

Step 1:

Data obtained from the question:

Equilibrium constant (Ka) = 1.8×10^-5

Concentration of acetic acid, [CH3COOH] = 0.100 M

Concentration of hydronium ion, [H3O+] =..?

Step 2:

The balanced equation for the reaction.

CH3CO2H(aq) + H2O(l) ⇌ H3O+(aq) + CH3CO2-(aq)

Step 3:

Determination of concentration of hydronium ion, [H3O+].

This can be obtained as follow:

Ka = [H3O+] [CH3CO2-] / [CH3CO2H]

Initial concentration:

[CH3COOH] = 0.100 M

[H3O+] = 0

[CH3CO2-] = 0

During reaction

[CH3COOH] = – y

[H3O+] = +y

[CH3CO2-] = +y

Equilibrium:

[CH3COOH] = 0.1 – y

[H3O+] = y

[CH3CO2-] = y

Ka = [H3O+] [CH3CO2-] / [CH3CO2H]

1.8×10^-5 = y × y / 0.1

Cross multiply

y^2 = 1.8×10^-5 x 0.1

Take the square root of both side

y = √(1.8×10^-5 x 0.1)

y = 1.3×10^-3 M

[H3O+] = y = 1.3×10^-3 M

Therefore, the concentration of the hydronium ion, [H3O+] is 1.3×10^-3 M

Answer: come on lets link can do what i do

Answer:

Explanation:

Mg + 2HCl = Mg Cl₂ + H₂

.594 g = .594 / 24.3

= .02444 mole

Heat evolved = msΔ T , m is mass of water ( solvant ) , s is specific heat of water , Δ T is rise in temperature

= 100 x 4.2 x ( 41.83 - 25 )

= 7068.6 J

.02444 mole  of Mg evolves 7068.6 J of heat

1 mole of Mg evolves 7068.6 /.02444 J

= 289222.6 J

= 289 kJ .

Molar heat enthalpy = 289 kJ .

Answer:

See explaination

Explanation:

1. The addition of group 3A elements to group 4A semiconductors decreases the conductivity of the group 4A semiconductors: Wrong

The addition of 3A group elements inreases the conductivity and make them extrinsic semiconductors( p-type)

2. The conductivity of semiconductors can be increased by the doping process.: Correct

3.As the temperature increases, the conductivity of semiconductors decreases.. wrong

As the temperature increases, the conductivity of semiconductors increases.

4. The addition of group 5A elements to group 4A semiconductors increases the conductivity of the group 4A semiconductors: Correct : They will create n-type semicoductor.

5.Holes are charge carriers in p-type semiconductors: Correct

6. Electrons are charge carriers in n-type semiconductors: Correct

Answer:

Specific heat capacity of iron (C) = 0.3 J/GK

Explanation:

Given:

Mass of sample (m) = 125 gram

Change in heat (ΔT) = 20°C - 0°C = 20°C

Absorbed energy (ΔE) = 750 J

Find:

Specific heat capacity of iron (C) = ?

Computation:

⇒ Specific heat capacity of iron (C) = ΔE / [mΔT]

⇒ Specific heat capacity of iron (C) = 750 / [125 × 20]

⇒ Specific heat capacity of iron (C) = 750 / [2,500]

⇒ Specific heat capacity of iron (C) = 0.3 J/GK

Answer:

Specific heat capacity of iron (C) [tex]= 0.3[/tex] J/g°C

Explanation:

As we know that

Specific heat capacity of iron (C) [tex]=\frac{\delta E}{ [m* \delta T]}[/tex]

Where [tex]\delta E[/tex] represents the change in the energy

m represents the mass of the sample and

[tex]\delta T[/tex] represents the change in temperature.

Given:

Mass of sample (m) [tex]= 125[/tex] gram

Change in heat ([tex]\delta T[/tex] ) [tex]20 - 0 = 20[/tex]

Absorbed energy ([tex]\delta E[/tex])[tex]= 750[/tex] J

Substituting the given values in above equation, we get -

Specific heat capacity of iron (C)

[tex]= \frac{750}{125*20}[/tex]

Specific heat capacity of iron (C) [tex]= 0.3[/tex] J/g°C

Answer:

the claim is that when people avoid storms they hide in any secret place in there house

Explanation:

when people do that they don't even have to worry about a single thing that will happen to them

Answer:

C

Explanation:

The reflection if sunlight on the water makes the water look silver,gray,white

Answer:

[tex]M_2=0.51M[/tex]

Explanation:

Hello,

In this case, for this dilution process, we understand that the moles of the solute (potassium nitrate) remain unchanged upon the addition of diluting water. However, the resulting or final volume includes the added water as shown below:

[tex]V_2=300mL+50mL=350mL[/tex]

In such a way, we are able to relate the solution before and after the dilution by:

[tex]V_1M_1=V_2M_2[/tex]

Hence, we solve for the final molarity as:

[tex]M_2=\frac{M_1V_1}{V_2}=\frac{0.6M*300mL}{350mL}[/tex]

Best regards.

[tex]M_2=0.51M[/tex]

Answer:

0.001 M

Explanation:

The pH scale is used to determine the acidity or basicity of a solution.

The pH is related to the concentration of hydrogen ions through the following expression.

pH = -log [H⁺]

[H⁺] = antilog -pH = antilog - 3 = 0.001 M

Answer:

A. The Swallowing reflex

Explanation:

Dysphagia Is a a condition that makes swallowing difficult.

Answer:

The absorption and strength of the H-beta lines change with the temperature of the stellar surface, and because of this, one can find the temperature of the star from their absorption lines and strength. To better comprehend, let us look into the concept of the atom's atomic structure.  

Atoms possess distinct energy levels and these levels of energy are constant, that is, the temperature has no influence on it. However, temperature possesses an influence on the electron numbers found within these levels of energy. Therefore, to generate an absorption line of hydrogen in the electromagnetic spectrum's visible band, the electrons are required to be present in the second energy level, that is when it captivates a photon.  

Therefore, after captivating the photons the electrons jump from level 2 to level 4, which shows that there is an increase in the stellar surface temperature and at the same time one can witness a decline in the strength of the H-beta lines. In case, if the temperature of the surface increases too much, then one will witness no attachment of electron with the hydrogen atom and thus no H lines, and if the temperature of the surface becomes too low, then the electrons will stay in the ground state and no formation of H lines will take place in that condition too.  

Hence, to generate a very robust H line, after captivating photons the majority of the electrons are required to stay in the second energy level.  

Answer:

[tex]M=1.1M[/tex]

Explanation:

Hello,

In this case, since we are mixing two NaOH solutions, the first step is to compute the total moles once the mixing is done, by using the volumes and concentrations of each solutions and subsequently adding them:

[tex]n_T=2.0L*0.60\frac{mol}{L}+495mL*\frac{1L}{1000mL}*3.0\frac{mol}{L}= 2.7molNaOH[/tex]

Next, we compute the total volume by adding the volume of each solution:

[tex]V_T=2.0L+495mL*\frac{1L}{1000mL}= 2.495L[/tex]

Finally, we compute the molarity of the resulting solution by the division between the total moles and the total volume:

[tex]M=\frac{2.7mol}{2.495L}\\ \\M=1.1M[/tex]

Best regards.

hEy!!!

Chlorine(CL) is the symbol for the entity that has 17 protons,20 neutrons and 18 electrons.

Hope it will be helpful to you...

Answer:chlorine

Explanation:

Answer:

the European countries grew together.

Explanation:

Europe saw human inflows from east and southeast.

the Roman Empire came to dominate the entire Mediterranean basin.

European politics from 1947 to 1989 made the European countries grew together.

Answer:

.It is easily synthesized from the reaction of propylene with sulfuric acid, followed by hydrolysis. Isopropyl alcohol (2-propanol) is made by indirect hydration of propylene (CH2CHCH3).… In some cases the hydration of propylene is carried out in one step, using water and a catalyst at high pressure.

Hope it'll help!

stay safe:)

Answer:

The first thing you will need to do is find some information about your element. Go to the Periodic Table of Elements and click on your element. If it makes things easier, you can select your element from an alphabetical listing.

Number of Protons = Atomic Number

Number of Electrons = Number of Protons = Atomic Number

Number of Neutrons = Mass Number - Atomic Number

For krypton:

Number of Protons = Atomic Number = 36

Number of Electrons = Number of Protons = Atomic Number = 36

Number of Neutrons = Mass Number - Atomic Number = 84 - 36 = 48

Explanation:

hope this helps, have a good day :-)

Answer:

Avagadro's Law- Gives the relationship between volume and amount of gas in moles when pressure and temperature are held constant. If the amount of gas in a container is increased, the volume increases. ... This means more impacts on the walls of the container and an increase in the pressure.

Explanation:

Answer:

Explanation:

Hello!

a)

You have an integral membrane protein (Bacteriorhodopsin) that uses solar energy to pump protons out of the cell against its electrochemical gradient.

To calculate the energy needed by the protein to pump one molecule out of the cell you need to apply the free energy difference equation for a charged molecule:

ΔG= 2.303RTlog₁₀[tex](\frac{[H^+]out}{[H^+]in})[/tex]+zFΔV

Where

ΔG= free energy difference per molecule transferred from the inside to the outside

R= gas constant 8.315*10⁻³ kJ/mol

T= Temperature in Kelvin (273.15 + TºC)

z= Valency of the ion (ej Na⁺ is z= +1 and Cl⁻ is z= -1)

F= Faraday constant 96.5 kJ/V*mol

ΔV= membrane potential (Volts)

The information you have is:

Intracellular pH= 9.4

Extracellular pH= 6.4

ΔV= 120 mV

Temperature 27ºC

Using the values of pH you can calculate the intracellular and extracellular proton concentrations:

Remember the pH of a solution is calculated as pH=-log[H⁺] so if you reverse the logarithm, you'll find the concentration of protons:

b= logₐ C ⇒ C= aᵇ

[H⁺]intracelular= 10⁻⁹'⁴

[H⁺]extracelular= 10⁻⁶'⁴

Now you need to match the units of the temperature and electrical gradient to the ones in the equation:

The temperature needs to ve in Kelvin: T= 273.15 + 27ºC= 300.15K

The electrical gradients need to be in Volts: ΔV= 120 mV= 0.12V

Now you can replace the data in the formula and calculate how much energy is needed to pump one proton outside the cell:

ΔG= 2.303RTlog₁₀[tex](\frac{[H^+]out}{[H^+]in})[/tex]+zFΔV= 2.303*( 8.315*10⁻³ kJ/mol)*300.15K*log[tex](\frac{10^{-6.4}}{ 10^{-9.4}} )[/tex]+(+1)*96.5 kJ/V*mol*0.12V= 28.82 kJ/mol

It costs 28.82 kJ/mol to pump one mole of H⁺ outside the cell.

b)

To synthesize one molecule of ATP the ATP synthase uses the electrical gradient produced by the spontaneous pass of protons through the membrane. This process is called the proton-motive force.

The ATP synthase consists of two subunits F₀ and F₁ with a rotational motor mechanism that allows it to produce and release ATP.

F₁ has the subunits α, β, σ, γ, ε in charge of synthesizing ATP

F₀ is a proton pore, made of 3 subunits a, b and c. 6 subunits c make up the transmembrane ring in charge of rotation, this ring is connected to the subunits γ and ε. Each time a proton passes, it makes the ring rotate which makes the subunits γ rotate.

Each time the subunit γ rotates 360º, 3 ATP molecules are synthesized and freed. A full rotation of γ means that the c-ring also made a full rotation (for this you need one proton per subunit)

If the ring has 6 c-subunits and, then each ATP molecule needs 6/3= 2 protons to need to pass for each ATP molecule.

I hope this helps!

Answer:

mdjnibfziedosnninjd.zjcssksskskbsksbivfdlvdxkvfuwhiwhwonsk jsbudwuvsaeigdOhgrauvdslnzarm cxwmvakbxsabxwrifwzpgsdoh

ds

Answer:

(decreasing particle size) C

Explanation: That is one of the answers, if there are more I am sorry.

Answer:

-1

Explanation:

Answer:

density

Explanation:

Density is an important measurement. It has an unit: g/mL or kg/L, ...

Evaporation, freezing, melting are the processes in which the substances change their states. Other processes are: condensation, sublimation, deposition.

...

Hope this answer can help you. Have a nice day!

Answer:

[tex]m_{PbI_2}=18.2gPbI_2[/tex]

Explanation:

Hello,

In this case, we write the reaction again:

[tex]Pb(NO_3)_2(aq) + 2 KI(aq)\rightarrow PbI_2(s) + 2 KNO_3(aq)[/tex]

In such a way, the first thing we do is to compute the reacting moles of lead (II) nitrate and potassium iodide, by using the concentration, volumes, densities and molar masses, 331.2 g/mol and 166.0 g/mol respectively:

[tex]n_{Pb(NO_3)_2}=\frac{0.14gPb(NO_3)_2}{1g\ sln}*\frac{1molPb(NO_3)_2}{331.2gPb(NO_3)_2} *\frac{1.134g\ sln}{1mL\ sln} *96.7mL\ sln\\\\n_{Pb(NO_3)_2}=0.04635molPb(NO_3)_2\\\\n_{KI}=\frac{0.12gKI}{1g\ sln}*\frac{1molKI}{166.0gKI} *\frac{1.093g\ sln}{1mL\ sln} *99.8mL\ sln\\\\n_{KI}=0.07885molKI[/tex]

Next, as lead (II) nitrate and potassium iodide are in a 1:2 molar ratio, 0.04635 mol of lead (II) nitrate will completely react with the following moles of potassium nitrate:

[tex]0.04635molPb(NO_3)_2*\frac{2molKI}{1molPb(NO_3)_2} =0.0927molKI[/tex]

But we only have 0.07885 moles, for that reason KI is the limiting reactant, so we compute the yielded grams of lead (II) iodide, whose molar mass is 461.01 g/mol, by using their 2:1 molar ratio:

[tex]m_{PbI_2}=0.07885molKI*\frac{1molPbI_2}{2molKI} *\frac{461.01gPbI_2}{1molPbI_2} \\\\m_{PbI_2}=18.2gPbI_2[/tex]

Best regards.

Answer:

Power, P = 300 W

Explanation:

We have,

Force acting on the box to take it is 300 N

It is moved to a distance of 10 m in 10 seconds

It is required to find the power required to move the box. The rate at which work is done is called power required by an object. It can be given by the formula as follows :

[tex]P=\dfrac{W}{t}\\\\P=\dfrac{Fd}{t}\\\\P=\dfrac{300\times 10}{10}\\\\P=300\ W[/tex]

So, the power required is 300 W.

Answer:

Liquid A.

Explanation:

Specific heat is defined as the amount of heat required per unit of mass to raise the temperature by one degree celsius.

When two liquids are heated, the liquid with larger specific heat is the one which is hotter. That is because is required more energy to decrease its temperature by 1°C.

Thus, in the problem, liquid A has the larger specific heat

Answer:

Catenation refers to the ability of an atom to link to other atoms of the same kind to form a chain.

Explanation:

Catenation is the binding of an element to itself through covalent bonds to form chain or ring .Catenation can also be defined as the self-linking of atoms of an element to form chains and rings. This definition can be extended to include the formation of layers like two-dimensional catenation and space lattices like three-dimensional catenation. Thus, we can boldly say that, Catenation occurs when atoms of the same element covalently bond to one another to create a chain or ring.

Catenation occurs most readily in carbon, forming covalent bonds to and longer chains and structures with other carbon atoms. This is why the vast number of organic compounds are found in nature. Carbon is best known for its catenation properties, with the analysis of catenated carbon structures in organic chemistry.

Carbon is by no means the only element capable of forming such catenae, however, and several other main group elements are capable of forming a wide range of catenae, including silicon, sulfur, and boron. In group 14, the high bond energy of carbon makes it able to self-link almost indefinitely when compared with other members of the group which form only a few bonds to other atoms of the same element.