Select the correct answer. What affects the efficiency of a heat engine? A. high friction between hot and cold reservoirs B. the heat difference between hot and cold reservoirs C. low friction between hot and cold reservoirs D. the temperature difference between hot and cold reservoirs

Answer:

1. For the central boron atom:

A. The number of lone pairs = 0.

B. The number of single bonds = 3.

C. The number of double bonds = 0.

2. The central boron atom B. Has an incomplete octet.

Explanation:

Hello,

In this case, as shown on the attached picture containing the required Lewis structure of boron chloride, we can see that:

1. For the central boron atom:

A. The number of lone pairs = 0 since all the three valance electrons are bonded with the chlorine atoms.

B. The number of single bonds = 3 as each chlorine atom needs only one bond to obey the octet.

C. The number of double bonds = 0 considering the previous explanation.

2. The central boron atom B. Has an incomplete octet since it reaches six electrons only from its initial three and other three provided by the three chlorine atoms.

Regards.

Answer:

a. True

Explanation:

In this reaction, we will have a hydride transfer to the carbon of the carbonyl group, moving the electrons of the double bond towards the oxygen producing a negative charge. The double bond is then regenerated by removing the chlorine atom from the molecule, producing an aldehyde.

Then, another molecule the LiAlH4 transfers another hydride to the carbon of the carbonyl group, again producing a negative charge on the oxygen. Finally, the hydrogen is protonated producing a primary alcohol.

See figure 1

I hope it helps!

Answer:

37.1 mL

Explanation:

To accurately read the measurement using a cylinder, we read the measurement at the meniscus i.e measurement under the curve as shown in the diagram above.

The meniscus i.e the measurement under the curve as shown above is 37.1 mL.

Therefore, the volume of the liquid as obtained from the cylinder is 37.1 mL

Answer:

37.1 ml

Explanation:

a graduated cylinder's measurement is taken at the bottom of the meniscus

Answer:

B. Colloid

Explanation:

Colloid is a mixture that is made up of very small homogeneous particles, thus can not be separated into fractions. Its particles do not settle as other solution, but are evenly dispersed in the medium. Some examples are: liquid milk, jelly, rubber etc

Since colloid is a solution, thus it is made up of two parts; its particles and dispersing medium.

Answer:

Cu(NO3)2(aq)+Pb(s) ⇌ Pb(NO3)2(aq)+Cu(s)

Explanation:

If we look at the both reactions closely, we will quickly discover that the reaction CuSO4(aq)+Pb(s) ⇌ PbSO4(s)+Cu(s) involves PbSO4.

The compound PbSO4 is insoluble in water and sinks to the bottom of the reaction vessel. When this occurs, the concentration of Pb^2+ becomes low. This will bring about a low voltage in the cell.

On the other hand, Pb(NO3)2 is soluble in water hence the cell voltage in this case is higher than the former.

In the case when we look at both reactions so here we discovered that the reaction of

CuSO4(aq)+Pb(s) ⇌ PbSO4(s)+Cu(s) includes PbSO4.

The compound PbSO4 should be insoluble in water and sinks to the bottom of the reaction vessel. At the time When this occurs, the concentration of Pb^2+ becomes low. This will bring about a low voltage in the cell.

On the other hand, Pb(NO3)2 is soluble in water so the cell voltage in this case is more than the former.

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Answer:

Mass, m = 1.51 grams

Explanation:

It is given that,

The circumference of Aluminium cylinder, C = 13 mm = 1.3 cm

Length of the cylinder, h = 4.2 cm

We know that the density of the Aluminium is 2.7 g/cm³

Circumference, C = 2πr

[tex]r=\dfrac{C}{2\pi}\\\\r=\dfrac{1.3}{2\pi}\\\\r=0.206\ cm[/tex]

Density is equal to mass per unit volume.

[tex]d=\dfrac{m}{V}[/tex]

m is mass of the cylinder

V is the volume of the cylinder

[tex]V=\pi r^2h\\\\V=\dfrac{22}{7}\times0.206^2\times 4.2\\\\V=0.5601\ cm^3[/tex]

So,

[tex]m=d\times V\\\\m=2.7\times 0.5601\\\\m=1.51\ g[/tex]

So, the mass of the cylinder is 1.51 grams.

Answer:

2CH3OH + 3O2 --> 2CO2 + 4H2O

This is called Combustion of Methanol

Explanation:

Count the numbers of atoms on each sides and try to get the same amount of quantity on each sides, so you'll eventually get "balanced".

or

Watch this video: "How to Balance CH3OH + O2 = CO2+ H2O (Combustion of Methanol)"

Good luck with future work! Keep studying chemistry!

- D

Answer:

Nonmetallic elements form ions by gaining valence electrons to complete their outer shell.

The more valence electrons an element has in its outer shell, the easier it is to complete.

The fewer electron shells an element has, the easier it is to fill its outermost shell.

Reactivity in nonmetals increases as you go from left to right in a group, and

decreases as you go from top to bottom.

Explanation:

Nonmetallic elements form ions by gaining valence electrons to complete

their outer shell.

The more valence electrons an element has in its outer shell, the easier it is to complete.

The fewer electron shells an element has, the easier it is to fill its outermost shell.

Reactivity in nonmetals increases as you go from left to right in a group, and decreases as you go from top to bottom.

When there are more valence electrons then it makes it easy for the element

to complete its outermost shell as against if it was less as it would be harder

due to a bigger number of electrons needed.

Non metals are elements which accepts valence electrons to complete its

outermost shell and becomes negatively charged when this happens.

When an element has fewer electron shells then filling the outermost shell

will be easier as the electron shells require a lesser number of electrons and

increases as the number of shells increases.

This is because the tendency to accept electrons increases from left to right

and decreases down the group.

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Answer:

Please find the attachment to this question:

Explanation:

By eliminating the agent produced in the reaction, it will give a structure of the alkene. please find the given attachment.

Answer:

2 g/mL

Explanation:

The following data were obtained from the question:

Mass (m) = 5 g

Volume (V) = 2.5 mL

Density (D) =.?

Density is simply defined as the mass of substance per unit volume of the substance. Mathematically, it is expressed as:

Density (D) = mass (m) /volume (V)

D = m/V

With the above formula, we can obtain the density of the ball as follow:

Mass (m) = 5 g

Volume (V) = 2.5 mL

Density (D) =.?

D = m/V

D = 5/2.5

D = 2 g/mL

Therefore, the density of the ball is 2 g/mL.

Answer:

Hey there!

10000 gallons would be 37.85 cubic meters.

Let me know if this helps :)

Answer: 37.8501 m³

Explanation:

 10000.0 gal × 1 m³/264.2 gal

=37.8501 m³ (significant digits)

Answer:

Environmental science is also referred to as an interdisciplinary field because it incorporates information and ideas from multiple disciplines. Within the natural sciences, such fields as biology, chemistry, and geology are included in environmental science.

Explanation:

Environmental science is an interdisciplinary science because it integrates physics, biology, and geography  to the study of the environment, and the solution of environmental problems.

Environmental science is the field of science that studies the interactions of the physical, chemical, and biological components of the environment and the relationships .

Interdisciplinary science allows you to study according to your professional and academic abilities and goals .

Environmental science is an interdisciplinary science because it integrates physics, biology, and geography  to the study of the environment, and the solution of environmental problems.

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Answer:

(a). The solubility of [tex]BaCO_{3}[/tex] in pure water is [tex]4.4\times10^{-5}\ M[/tex]

(b). The solubility of [tex]BaCO_{3}[/tex] in solution is [tex]6.92\times10^{-9}\ M[/tex]

Explanation:

Given that,

(a). The solubility of [tex]BaCO_{3}[/tex] in pure water

(b). The solubility of [tex]BaCO_{3}[/tex] in a solution

Solubility of [tex]CO_{3}^{-2}[/tex] is 0.289 M

We know that,

The solubility product constant  of  [tex]BaCO_{3}[/tex] is [tex]2\times10^{-9}[/tex]

Let the solubility of [tex]BaCO_{3}[/tex] is s.

We need to calculate the solubility of [tex]BaCO_{3}[/tex] in pure water

Using formula of solubility

[tex]ksp=s\times s[/tex]

[tex]ksp=s^2[/tex]

[tex]s=\sqrt{ksp}[/tex]

Put the value into the formula

[tex]s=\sqrt{2\times10^{-9}}[/tex]

[tex]s=4.4\times10^{-5}\ M[/tex]

(b). We need to calculate the solubility of [tex]BaCO_{3}[/tex] in solution

Using formula of solubility

[tex]ksp=s\times s[/tex]

Put the value into the formula

[tex]2\times10^{-9}=s\times 0.289[/tex]

[tex]s=\dfrac{2\times10^{-9}}{0.289}[/tex]

[tex]s=6.92\times10^{-9}\ M[/tex]

Hence, (a). The solubility of [tex]BaCO_{3}[/tex] in pure water is [tex]4.4\times10^{-5}\ M[/tex]

(b). The solubility of [tex]BaCO_{3}[/tex] in solution is [tex]6.92\times10^{-9}\ M[/tex]

Answer:

Molar solubility of magnesium fluoride (MgF2) = 8.26 × 10⁻¹⁰ M

Explanation:

Given:

Ksp = 5.16 × 10⁻¹¹

NaF = 0.250

Find:

Molar solubility of magnesium fluoride (MgF2)

Computation:

Molar solubility of magnesium fluoride (MgF2) = Ksp / NaF²

Molar solubility of magnesium fluoride (MgF2) = 5.16 × 10⁻¹¹ / (0.250)²

Molar solubility of magnesium fluoride (MgF2) = 8.26 × 10⁻¹⁰ M

The molar solubility of magnesium fluoride (MgF2) is 8.26 × 10⁻¹⁰ M.

Since

Ksp = 5.16 × 10⁻¹¹

NaF = 0.250

Now we know that

Molar solubility of magnesium fluoride (MgF2) = Ksp / NaF²

= 5.16 × 10⁻¹¹ / (0.250)²

= 8.26 × 10⁻¹⁰ M

hence, The molar solubility of magnesium fluoride (MgF2) is 8.26 × 10⁻¹⁰ M.

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Answer:

[tex][Cu]^{remaining}=0.357 M[/tex]

Explanation:

Hello,

In this case, we may use the following equation in order to compute the moles of copper that are processed, considering it goes from Cu⁰ to Cu²⁺, so two electrons are transferred:

[tex]n_{Cu}=\frac{2.68C/s*282s}{96500C/mol*2} =3.9x10^{-3}mol[/tex]

After that, we compute the initial moles of copper in the solution, considering that the concentration of copper (II) equals the concentration of copper:

[tex]n_{Cu,0}=0.366mol/L*0.425L=0.156mol[/tex]

In such a way, we can subtract the process moles to the initial moles to compute the remaining moles of copper:

[tex]n_{Cu}^{remaining}=0.156mol-0.0039mol=0.152mol[/tex]

Finally, the concentration is:

[tex][Cu]^{remaining}=0.152mol/0.425L[/tex]

[tex][Cu]^{remaining}=0.357 M[/tex]

Regards.

Answer:

[tex]V_2=19.23L[/tex]

Explanation:

Hello,

In this case, by using the Avogadro's law which allows us to understand the volume-moles behavior as a directly proportional relationship:

[tex]\frac{V_2}{n_2} =\frac{V_1}{n_1}[/tex]

We can compute the volume of 34.3 g of argon by representing it in mole as shown below:

[tex]n_1=1 mol\\\\n_2=34.3g*\frac{1mol}{39.95g} =0.859mol[/tex]

Thus, we find:

[tex]V_2=\frac{V_1*n_2}{n_1}=\frac{22.4L*0.859mol}{1mol} \\\\V_2=19.23L[/tex]

Best regards.

Answer:

d. sodium t-butoxide + bromomethane

Explanation:

Sodium t-butoxide is a strong base with the chemical formula  (CH3)3CONa and it is a non-nucleophilic base while bromomethane with the chemical formula CH3Br.

They both together gives 2-ethoxypropane (C5H12O).

(CH3)3CONa + CH3Br => C5H12O + NaBr

Hence, the correct option is "d".

Answer:

pH = 12.15

Explanation:

To determine the pH of the HCl and KOH mixture, we need to know that the reaction is  a neutralization type.

HCl  +  KOH  →  H₂O  +  KCl

We need to determine the moles of each compound

M = mmol / V (mL) → 30 mL . 0.10 M = 3 mmoles of HCl

M = mmol / V (mL) → 40 mL . 0.10 M = 4 mmoles of KOH

The base is in excess, so the HCl will completely react and we would produce the same mmoles of KCl

HCl  +  KOH  →  H₂O  +  KCl

3 m       4 m                       -

             1 m                      3 m

As the KCl is a neutral salt, it does not have any effect on the pH, so the pH will be affected, by the strong base.

1 mmol of KOH has 1 mmol of OH⁻, so the [OH⁻] will be 1 mmol / Tot volume

[OH⁻] 1 mmol / 70 mL = 0.014285 M

- log [OH⁻] = 1.85 → pH = 14 - pOH → 14 - 1.85 = 12.15

The pH of the solution is 12.15.

The following equation should be

HCl  +  KOH  →  H₂O  +  KCl

Here we have to measured the moles of each compound i.e.

M = mmol / V (mL) → 30 mL . 0.10 M = 3 mmoles of HCl

M = mmol / V (mL) → 40 mL . 0.10 M = 4 mmoles of KOH

So, it be like

3 m       4 m                       -

           1 m                      3 m

Now the pH should be like

= [OH⁻] 1 mmol / 70 mL

= 0.014285 M

Now

= - log [OH⁻] = 1.85

pH = 14 - pOH

= 14 - 1.85

= 12.15

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Answer:

All non-zero digits are significant

Explanation:

Answer:

Thinking...

o-O

(ﾉ◕ヮ◕)ﾉ*:･ﾟ✧

Answer:

The correct answer is 0.058

Step-by-step explanation:

The mole fraction of KI (X) in the solution is the number of moles of KI divided into the total number of moles of the solution (nt):

X= moles KI/nt

First we have to calculate the molecular weights of the components of the solution: KI and water (H₂O):

Molecular weight (Mw) of KI:

Mw(KI)= 39 g/mol + 127 g/mol = 166 g/mol

Molecular weight of H₂O:

Mw(H₂O)= (1 g/mol x 2) + 16 g/mol = 18 g/mol

Then, we calculate the number of moles there is of each component in the solution by dividing the mass into Mw:

Moles of KI= mass KI/Mw(KI) = 3.4 g/166 g/mol = 0.020 mol KI

Moles of H₂O= mass H₂O/Mw(H₂O)= 5.8 g/18 g/mol = 0.322 mol H₂O

Thus, the total moles of solution will be:

nt= moles KI + moles H₂O= 0.020 mol + 0.322 mol = 0.342 mol

Finally, we divide the moles of KI into the total moles of solution (nt) to obtain the mole fraction (X):

X= moles KI/nt = 0.020 mol/0.342 mol = 0.058

This means a release of free energy from the system corresponds to a negative change in free energy, but to a positive change for the surroundings.

Answer:

[tex]Q=108.55kJ[/tex]

Explanation:

Hello,

In this case, we can compute the required heat by using the following equation:

[tex]Q=mCp(T_2-T_1)[/tex]

Thus, by considering the given mass, specific heat and both initial and final temperature, we obtain:

[tex]Q=500g*1.67\frac{J}{g\°C} *(150.0\°C-20.0\°C)*\frac{1kJ}{1000J} \\\\Q=108.55kJ[/tex]

Regards.

Answer:

a. the anode.

Explanation:

An anode is an electrode through which the conventional current enters into a polarized electrical device. This contrasts with a cathode, an electrode through which conventional current leaves an electrical device

hope it helps :)

please mark it the brainliest!

Answer: the cathode, by convention the components of the cathode are always listed last

Answer:

He studied the way in which the elements combined during chemical reactions

Explanation:

Which method did Dalton use to develop his atomic theory?

D.) He studied the way in which elements combined during chemical reactions.

Answer: It’s D

Explanation:

Answer:

[tex]1.53~moles~CH_2Cl_2[/tex].

Explanation:

We can start with the reaction, if we know the formula for each compound:

-) Methane: [tex]CH_4[/tex]

-) Carbon tetrachloride: [tex]CCl_4[/tex]

-) Dichloromethane: [tex]CH_2Cl_2[/tex]

With this in mind, we can write the reaction:

[tex]CH_4~+~CCl_4~->~CH_2Cl_2[/tex]

Now, we can balance the reaction:

[tex]CH_4~+~CCl_4~->~2CH_2Cl_2[/tex]

After this, we have 2 carbon atoms on each side, 4 hydrogen atom on each side, and 4 chlorine atoms on each side.

If we want to know how many moles of [tex]CH_2Cl_2[/tex] would be produced with .766 moles of [tex]CH_4[/tex], we have to check the balanced reaction and use the molar ratio. In this case, the molar ratio is 1 mol [tex]CH_4[/tex] will produce 2 moles of [tex]CH_2Cl_2[/tex] (1:2). So:

[tex]0.766~moles~CH_4\frac{2~moles~CH_2Cl_2}{1~mol~CH_4}=1.53~moles~CH_2Cl_2[/tex]

We wil have [tex]1.53~moles~CH_2Cl_2[/tex].

I hope it helps!

Answer:

B. a beaker used in an experiment

Explanation:

Answer:

[tex]v_{rms}=866.32m/s[/tex]

Explanation:

Hello,

In this case, since the rms speed of the molecules is computed by:

[tex]v_{rms}=\sqrt{\frac{3RT}{M} }[/tex]

Whereas the absolute temperature is computed from the internal energy (by using the Cp of helium (3.1156 J/g*K) as shown below:

[tex]U=nCvT\\\\T=\frac{U}{nCv}=\frac{15kJ*\frac{1000J}{1kJ} }{10mol*\frac{4.00g}{1mol} *3.1156\frac{J}{g*K} } \\\\T=120.36K[/tex]

Thereby, the rms speed results:

[tex]v_{rms}=\sqrt{\frac{3*8.314\frac{kg*m^2}{s^2*mol*K}*120.36K}{4.00\frac{g}{mol}*\frac{1kg}{1000} } } \\\\v_{rms}=866.32m/s[/tex]

Regards.

Answer:

pH will be increased.

Explanation:

When you mixed sodium acetate and acetic acid,  pH will be maintained and will have slight changes. This constitutes what is known as a buffer solution.

But if you analize the reactions:

First of all, you have a weak acid, acetic:

CH₃COOH   +  H₂O  ⇄  CH₃COO⁻  +   H₃O⁺      Ka

And the salt can be dissociated as:

NaCH₃COO →  CH₃COO⁻  +   Na⁺

As you are adding acetate, this is the conjugate strong base from the weak acid and as every base, it brings hydroxides to medium, so the pH will be increased. Protons from the acid will be neutralized, thouhgh.

CH₃COO⁻  +   H₂O  ⇄  CH₃COOH + OH⁻     Kb

Allene (1,2-propadiene) has point group D2d, itself is achiral because it has two planes of symmetry. ... An allene with substituents on one terminal carbon atom are unlike and substituent on other terminal carbon atoms are same, allene will be achiral. It will have one symmetry plane.

Hope this helped :)