Suppose a reaction mixture, when diluted with water, afforded 300 mL of an aqueous solution of 30 g of the reaction product malononitrile [CH2(CN)2], which is to be isolated by extraction with ether. The solubility of malononitrile in ether at room temperature is 20.0 g/100 mL, and in water is 13.3 g/100 mL. What weight of malononitrile would be recovered by extraction with (a) three 100-mL portions of ether and (b) one 300-mL portion of ether

Answer:

1.63 V

Explanation:

Let us state the reaction equation again for the purpose of clarity;

2MnO4^-(aq)+16H+(aq)+5Pb(s)-->2Mn^2+(aq)+8H2O(l)+5Pb^2+(aq)

The reduction potentials for the two half reaction equations are;

MnO 4 - (aq) + 8H + (aq) + 5e - → Mn2+(aq) + 4H2O(l) Eo=1.51 V

Pb2+(aq) + 2e - → Pb(s) Eo= -0.13 V

E°cell = E°red – E°Ox

E°cell = 1.51 - (-0.13)

E°cell = 1.51 + 0.13

E°cell = 1.64 V

But Q= [Mn^2+]^2 [Pb^2+]^5/[MnO4^-]^2 [H^+]^16

Q= [3.23]^2 [6.62]^5/[1.87]^2 [1.37]^16

Q= 10.43 × 12714.22/3.4969 × 154

Q= 132609.3/538.5226

Q= 246.25

From Nernst equation

E= E° - 0.0592/n log Q

Where n=10

E= 1.64- 0.0592/10 log 246.25

E= 1.64-0.0142

E= 1.63 V

Answer:

One of the organelles in eukaryotic cells that carry out digestion and waste removal.

Answer:

It's X

Explanation:

Answer: The molal boiling point elevation constant [tex]k_b[/tex] of X is [tex]2.4^0C/m[/tex]

Explanation:

Formula used for Elevation in boiling point :

[tex]\Delta T_b=k_b\times m[/tex]

or,

[tex]T_b-T^o_b=i\times k_b\times \frac{w_2\times 1000}{M_2\times w_1}[/tex]

where,

[tex]T_b-T^o_b =(125.2-120.7)^0C=4.5^0C[/tex]

[tex]k_b[/tex] = boiling point constant  = ?

m = molality

[tex]w_2[/tex] = mass of solute (urea) = 55.4 g

[tex]w_1[/tex] = mass of solvent  X =  500 g

[tex]M_2[/tex] = molar mass of solute (urea) = 60 g/mol

Now put all the given values in the above formula, we get:

[tex]4.5^oC=k_b\times \frac{55.4g\times 1000}{60\times 500g}[/tex]

[tex]k_b=2.4^0C/m[/tex]

Thus the molal boiling point elevation constant [tex]k_b[/tex] of X is [tex]2.4^0C/m[/tex]

Answer:

The simplest chemical formula of the compound is Cu(C₆H₁₁O₇)₂

Explanation:

Given mass of sample = 1.4 g

mass of copper in the sample = 0.2 g

mass of the gluconate =1.4 - 0.2 = 1.2 g

The mole ratio is determined first using the formula;

mole ratio = reacting mass / atomic mass

atomic mass of copper = 63.55

mass of gluconate, C₆H₁₁O₇ = 12*6 + 1*11 + 16*7 = 195 g/mol

mole ratio ( copper : gluconate) = 0.2/63.55 : 1.4/195

mole ratio ( copper : gluconate) =  0.003 : 0.007

convert to whole number ratios by dividing with the smallest ratio

mole ratio ( copper : gluconate) = 0.003/0.003 : 0.007/0.003

mole ratio ( copper : gluconate) = 1 : 2

Therefore, the simplest chemical formula of the compound is Cu(C₆H₁₁O₇)₂

Answer:

water stored in a dam

Explanation:

when the water is in dam it is ready to move bit is not moving

Answer:

21 mL of NaOH is required.

Explanation:

Balanced reaction: [tex]HBr+NaOH\rightarrow NaBr+H_{2}O[/tex]

Number of moles of HBr in 11.0 mL of 0.30 M HBr solution

= [tex](\frac{0.30}{1000}\times 11.0)[/tex] moles = 0.0033 moles

Let's say V mL of 0.16 M NaOH solution is required to reach equivalence point.

So, number of moles of NaOH in V mL of 0.16 M NaOH solution

= [tex](\frac{0.16}{1000}\times V)[/tex] moles = 0.00016V moles

According to balanced equation-

1 mol of HBr is neutralized by 1 mol of NaOH

So, 0.0033 moles of HBr are neutralized by 0.0033 moles of NaOH

Hence, [tex]0.00016V=0.0033[/tex]

           [tex]\Rightarrow V=\frac{0.0033}{0.00016}=21[/tex]

So, 21 mL of NaOH is required.

Answer:

1. Born Haber cycle is used to calculate enthalpy of formation of an ionic solid

2. Resonance structures are used to represent the bonding in some chemical species.

Explanation:

The Born–Haber cycle is a method popularly known in chemistry used in computing enthalpy. The enthalpy of formation of an ionic solid cannot be measured directly. The lattice enthalpy refers to the enthalpy change involved in the formation of an ionic compound from gaseous ions the process is exothermic process. A Born–Haber cycle works on the principle of Hess's law. It can be used to calculate the lattice enthalpy by comparing the standard enthalpy change of formation of the ionic compound from the elements to the enthalpy required to make gaseous ions from the elements.

Resonance is an idea introduced by Linus Pauling to explain chemical bonding from the valence bond perspective. The idea of resonance affords us the opportunity to describe the bonding in certain molecules by combining several structures called chemical or canonical structures. The real structure of the specie lie somewhere between the structures indicated by the resonance structures. The resonance structures of the nitrate ion are shown in the image attached.

Answer:

Explanation:

a )

m = m₀ [tex]e^{-\lambda t[/tex]

m is mass after time t . original mass is m₀ , λ is disintegration constant

λ = .693 / half life

= .693 / 1590

= .0004358

m = m₀ [tex]e^{- 0.0004358 t}[/tex]

b )

m = 50 x [tex]e^{-.0004358\times 500}[/tex]

= 40.21 mg .

c )

40 = 50 [tex]e^{-.0004358t[/tex]

.8 = [tex]e^{-.0004358t[/tex]

[tex]e^{.0004358t[/tex] = 1.25

.0004358 t = .22314

t = 512 years .

Answer:

polar covalent bonds with partial negative charges on the F atoms.

Explanation:

A covalent bond could be polar or nonpolar depending on the relative electro negativity difference between the two bonding atoms. In this case, the bonding atoms are chlorine and fluorine.

In the Pauling's scale, fluorine has an electro negativity value of 3.98 while chlorine has an electro negativity value of 3.16. The difference in electro negativity between the two atoms is about 0.82. This magnitude of electro negativity difference between the two bonding atoms correspond to the existence of a polar covalent bond in the molecule.

The direction of the dipole depends on the relative electro negativity values of the two bonding atoms. Since fluorine is more electronegative than chlorine, the fluorine atom will be partially negative and the chlorine atom will be partially positive accordingly.

The compound ClF (chlorine monofluoride) contains polar covalent bonds with partial negative charges on the F atoms. Therefore, option D is correct.

In ClF, chlorine (Cl) is more electronegative than fluorine. As a result, the shared electrons in the Cl-F bond are pulled closer to the chlorine atom, creating a partial negative charge on the fluorine atoms and a partial positive charge on the chlorine atom.

This polarity in the Cl-F bond gives the molecule an overall polarity, making it a polar molecule. Thank you for pointing out the error, and I apologize for any confusion caused.

Thus, option D is correct.

To learn more about the polar covalent bonds, follow the link:

https://brainly.com/question/28295508

#SPJ6

Answer:

Explanation:

use gas law eqation

P1 * V1  / T1 = P2 * V2 /T2

600*V1/227 = 300*800/23

V1 = 300*800*227 / 23*600 = ............ can you solve this and get the answer?

Answer: Gas–liquid–solid triple point

The single combination of pressure and temperature at which liquid water, solid ice, and water vapor can coexist in a stable equilibrium occurs at approximately 273.1575 K (0.0075 °C; 32.0135 °F) and a partial vapor pressure of 611.657 pascals (6.11657 mbar; 0.00603659 atm).

Explanation:

It represents the equilibrium between the liquid and gas phases. The point on this curve where the vapor pressure is 1 atm is the normal boiling point of the substance. The vapor-pressure curve ends at the critical point (B), which is at the critical temperature and critical pressure of the substance.

Answer:

Decantation by means of difference in relative densities.

Explanation:

The specific gravity (relative density) of the gold to the soil/sand is the physical property exploited in panning gold. The particles with lower density would float whilst the heavier gold sinks lower to the bottom of the pan by gravity and is decanted off.

I hope this explanation is easy to comprehend.

Answer:

1.The electrode on the right is positive

2. 0.058V

Explanation:

The above cell is a concentration cell.

A concentration cell is an electrolytic cell that is made of two half-cells with the same electrodes, but differs in concentrations of the solutions. A concentration cell functions by diluting the more concentrated solution and concentrating the more dilute solution, creating a voltage as the cell reaches an equilibrium thereby transferring the electrons from the cell with the lower concentration to the cell with the higher concentration.

In the above cell, electrons flow from the left electrode (less concentrated) to the right electrode (more concentrated). Therefore, the right electrode is the positive electrode (cathode).

Part 2: Please, see the attachment below for the calculations.

Answer:  a.CCl4 aka carbon tetrachloride

Explanation:

ionic compounds and polar molecules can be dissolved in water which is a polar solvent.

choice d (KF) is a salt (an ionic compound) and can be dissolved in water /(K+ and F- ions would be formed in water).

choice c (NH3 or ammonia) is a very polar molecule and thus can be dissolved in water(Hydrogen bonding).

choice b (CH3Cl) is slightly polar because the atoms surrounding the central carbon atom are different(3 H atoms and 1 chlorine atom) and can be dissolved in water(Dipole-dipole interaction).

choice a is nonpolar and cannot be dissolved in water.

Answer:

N2H4

Explanation:

A hydride is a binary compound of hydrogen and another element. Binary compounds contain only two atoms. We have to x-ray the hydrides of nitrogen given in the question in order to make our choice. Remember that we were told that that the hydride contains its own volume of nitrogen and twice its volume of hydrogen.

Now consider the hydride N2H4.

N2H4(g) -----> N2(g) + 2H2(g)

The volume ration of nitrogen gas to hydrogen gas in N2H4 is 1:2.

The molecular mass of the compound is;

N2H4= 2(14) + 4(1)= 28+4= 32

Since

molecular mass= 2 vapour density

Vapour density= molecular mass/2

Vapour density= 32/2

Vapour density = 16

Therefore the hydride of nitrogen referred to in the question is N2H4

Answer: From your question,

One could be exothermic which means that the final enthalpy will be less than the initial enthalpy. H= Hf-Hi(Hf<Hi).

In Endothermic reaction, the entropy is lowered by absorbing energy in the surronding. By so doing, the surronding losses energy and the reaction is not spontaneous.

H is positive and S (entropy) is positive.

Explanation:

Exothermic reaction is the reaction where heat is released In the surronding which lead to increase in the surronding Temperature.

Endothermic reaction is the reaction that absorb heat from the surronding and decrease the surronding Temperature.

Answer:

[tex]_1^{1} {P}[/tex] is symbol for proton emission in the nucleus.

[tex]_2^{4} {He}[/tex] symbolises alpha emission, equivalent to helium atom emission of a radioactive particle

[tex]+_1^{0} {e}[/tex] is the radiation symbol for positiron particle. which occurs when beta + radioactive decay occurs

Answer:

D) Evaluating it with experimentation and argument.

Explanation:

If you don't have enough observational evidence, then you can't really strengthen your scientific knowledge, because you haven't collected enough information to answer the questions you're asking.

If you only have a few scientists working on a question, it will take longer to find an answer. With more people working on a concept, it can be solved in more time.

It can be good to create new hypotheses, but only if you've already tested your original hypothesis (with experimentation and argument), and it turned out to be wrong. Once you've rejected your first hypothesis, only then should you make a new one.

Answer:

D

Explanation:

Answer:

FOR EVERY 10 DEGREE CELSIUS INCREASE IN TEMPERATURE, THE ACTIVATION ENERGY THAT SHOWS THIS IS 52.4 KJ/MOL

Explanation:

From Arrhenius equation, the relationship between the rate constant and the temperature is as shown below:

k = Ae^ -Ea/RT

At initial temperature T1, the initial rate constant is (k1)

At final temperature T2, the final rate constant is k2

For the reaction rate to be doubled, we must double the rate constant which shows that the ratio of k2 / k1 must be equal to 2.

That is, k2 / k1 = 2 (rate is doubled)

Equating this into the Arrhenius equation, we have:

k2 / k1 = Ae^ (-Ea / R ) (1/ T2 - 1/T1)

2 = e^ (-Ea / R) (1 / T2 = 1 / T1)

Taking the natural logarithm of both sides:

ln 2 = - (Ea / R) (1 / T2 - 1 / T1)

Making Ea the subject of the formula, we obtain:

Ea = - (ln 2 R / (1 / T2- 1 / T1))

Let T1 = 25 C = 25 + 273 K = 298 K

T2 = 35 C = 35 + 273 K = 308 K

R = 8.314

So,

Ea = - (ln 2 * 8.314 / ( 1/308 - 1 / 298))

Ea = - (0.693 * 8.314 / 0.00324 - 0.00335)

Ea = - 5.7616 / -0.00011

Ea = 52 378,18 J / mol

So therefore, the activation energy Ea is 52.4 kJ/mol.

Answer: the exciation of molecules is brount by absorption of energy  in spectroscpy

Explanation:

Answer:

E. The ratio of [HNO2] / [NO2-] will increase

D. The pH will decrease.

Explanation:

Nitrous acid ( HNO₂ ) is a weak acid and NaNO₂ is its salt . The mixture makes a buffer solution .

pH = pka + log [ salt] / [ Acid ]

= 3.4 + log .32 / .42

= 3.4 - .118

= 3.282 .

Now .16 moles of nitric acid is added which will react with salt to form acid

HNO₃ + NaNO₂ = HNO₂ + NaNO₃

concentration of nitrous acid will be increased and concentration of sodium nitrite ( salt will decrease )

concentration of nitrous acid = .42 + .16 = .58 M

concentration of salt = .32 - .16 = .16 M

ratio of [HNO₂ ] / NO₂⁻]

= .42 / .32 = 1.3125

ratio of [HNO₂ ] / NO₂⁻] after reaction

= .42 + .16 / .32 - .16

= 58 / 16

= 3.625 .

ratio will increase.

Option E is the answer .

pH after reaction

= 3.4 + log .16 / .58

= 2.84

pH will decrease.

Answer:

P is the limiting reagent

Explanation:

P = phosphorus  = 30.97g/mol

Cl2 = Chlorine = 70.91g/mol

PCl3 = Phosphorus Trichloride = 137.33g/mol

P + Cl2 = PCl3

Left Side

P = 1

Cl = 2

Right Side

P = 1

Cl = 3

So equation needs to be balanced first

2P + 3Cl = 2PCl3

Left Side

P = 2

Cl = 6

Right Side

P = 2

Cl = 6

That's better.

Ok so we have 12.39g of P so we have 0.4 moles of it

We then have 52.54g of Cl so we have 0.74 moles of it

For every P we need 1.5 Cl so we have an excess of Cl

Answer:

C) Steam condensing on a mirror

Explanation:

This was just a change in the physical state.

Answer:

A .    [tex]\mathbf{W = 7133.2 \dfrac{ft. lb_f}{min} }[/tex]

B.   [tex]\mathbf{W = 4245.24 \dfrac{ft. lb_f}{min} }[/tex]

C.  The system is at steady state but not at equilibrium

Explanation:

Given that:

The volumetric flow rate of the water = 15 gallons per minute

The diameter of the pipe that leaves the pump is 1 inch.

A. The objective here is  to determine how much work flow is done by the water as it leaves the pump and enters the pipe

The work flow that is said to be done can  be expressed by the relation :

W = P × V

where;

P = pressure

V = volume

Also the given outlet pressure is the gauge pressure

The pressure in the pump P  is can now be expressed by the relation:

[tex]P_{absolute} = P_{guage} + P_{atmospheric}[/tex]

[tex]P_{absolute}[/tex] =  10 psig + 14.7 psig

[tex]P_{absolute}[/tex] =  24.7 psig

W =  P × V

W =  24.7 psig  ×  15 gal/min

[tex]W = (24.7 \ psig * \dfrac{\frac{lb_f}{in^2}}{psig}) * ( 15 \frac{gal}{min}* \dfrac{0.1337 \ ft^3}{1 \ gal }* \dfrac{144 \ in^2}{1 \ ft^2})[/tex]

[tex]\mathbf{W = 7133.2 \dfrac{ft. lb_f}{min} }[/tex]

Thus ; the rate of flow of work is said to be done by the water at [tex]\mathbf{W = 7133.2 \dfrac{ft. lb_f}{min} }[/tex]

B.

Given that :

The water returns to the pool through an opening that is 1.5 inches in diameter.

where the pressure is 1 atm.

Then ; the rate of work done  by the water as it leaves the pipe and enter the pool is as follows:

W =  P × V

W = 1 atm  ×  15 gal/min

[tex]W = 1 \ atm * ( 15 \frac{gal}{min}* \dfrac{0.1337 \ ft^3}{1 \ gal }* \dfrac{144 \ in^2}{1 \ ft^2})[/tex]

[tex]\mathbf{W = 4245.24 \dfrac{ft. lb_f}{min} }[/tex]

Thus ; the rate of flow of work done by the water leaving the pipe and enters into the pool is  at [tex]\mathbf{W = 4245.24 \dfrac{ft. lb_f}{min} }[/tex]

C.

We can consider the system to be at steady state due to the fact that; the data given for the flow rate and pressure doesn't reflect upon the change in time in the space between the pump and the pool.

On the other-hand the integral factor why the system is not at equilibrium is that :

the pressure leaving the pipe is different from that of the water at the surface of the pool as stated in the question.

Answer:

The balanced equation is given below:

SiO2 + 4HF —> SiF4 + 2H2O

The coefficients are 1, 4, 1, 2

Explanation:

The equation for the reaction is given below:

SiO2 + HF —> SiF4 + H2O

The above equation can be balance by as follow:

There are 4 atoms of F on the right side and 1 atom on the left side. It can be balance by putting 4 in front of HF as shown below:

SiO2 + 4HF —> SiF4 + H2O

Therefore are 4 atoms of H on the left side and 2 atoms on the right side. It can be balance by putting 2 in front of H2O as shown below:

SiO2 + 4HF —> SiF4 + 2H2O

Now the equation is balanced.

Answer: Positive environmental changes.

Explanation: Without many humans around, the environment has been getting better as more sea life have been spotted in places they haven't been for decades, as well as clearer waters and less rubbish about. Pollution levels have dropped as there are barley any planes in the sky and not many cars about.

Answer:

honestly,i can say that socially being away from people reduces stress

Explanation:

Answer:

a) Can be cut into tiny pieces - Physical Change

b) Fizzling occurs when placed water -Chemical Change

c) Light is emitted when burned -Chemical Change

d) Turns to ash -Chemical Change

Explanation:

Answer:

Exothermic reaction.

Explanation: