At what temperature is the following reaction feasible: CaCO3 -> CaO + CO2?
Enthalpy data:
CaCO3: -1207 kJ/mol
CaO: -635 kJ/mol
CO2: -394 kJ/mol
Entropy data:
CaCO3: +93 J/K mol
CaO: +40 J/K mol
CO2:+214 J/K mol

Answer:

The gas evolved because of reaction of acid with metal carbonate or metal hydrogen carbonate turns lime water milky. This shows that the gas is carbon dioxide gas. This happens because of formation of white precipitate of calcium carbonate.

Hope it helps you!

The milky substance formed is CO₂ gas.

The gas evolved because of reaction of acid with metal carbonate or metal hydrogen carbonate turns lime water milky. This shows that the gas is carbon dioxide gas.

This happens because of formation of white precipitate of calcium carbonate.

Lime water turns milky when the gas liberated from an acidified carbonate solution is passed into it.

The liberated CO₂ reacts with lime water to give calcium bicarbonate as the precipitate.

Hence, the milky substance formed is CO₂ gas.

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Answer:

Option D.

Explanation:

This compound has in its formula:

- Eight bromines

- Four phosphorous

8 → octa prefix

4 → tetra prefix

Right answer is Octabromine tetraphosphide

It can not be option A, tetraphosphate is P4O7

It can not be B and C, we do not have B (boron)

Answer:

Octabromine tetraphosphide

Explanation:

Answer via Educere/ Founder's Education

Answer:

Check Explanation.

Explanation:

Formation reactions are chemical reactions where one mole of a compound is produced from its constituent elements in their standard states.

NaBr (s)

The Standard formation reaction is

Na (s) + (1/2)Br₂ (g) → NaBr (s)

Using appendix C, the standard heat of formation of NaBr(s) is

ΔH∘f = -359.8 kJ/mol.

SO₃ (g)

The Standard formation reaction is

S (s) + (3/2) O₂ (g) → SO₃ (g)

Using appendix C, the standard heat of formation of SO₃(g) is

ΔH∘f = -395.2 kJ/mol.

Pb(NO₃)₂ (s)

The Standard formation reaction is

Pb (s) + N₂ (g) + 3O₂ (g) → Pb(NO₃)₂ (s)

Using appendix C, the standard heat of formation of Pb(NO₃)₂(s) is

ΔH∘f = -451.9 kJ/mol.

Hope this Helps!!!

Answer:

Explanation:

Formation reactions are chemical reactions where one mole of a compound is produced from its constituent elements in their standard states.

Answer:

Gaseous

Explanation:

Gasses can move freely and do not form the shape of their containers

Liquids are more free than solids, but they conform to the shape of their container

Solids are not free

Answer: The empirical formula is [tex]PbO_2[/tex]

Explanation:

Mass of Pb =  4.33 g

Mass of O = (5.00-4.33) g = 0.67 g

Step 1 : convert given masses into moles

Moles of Pb =[tex]\frac{\text{ given mass of Pb}}{\text{ molar mass of Pb}}= \frac{4.33g}{207g/mole}=0.021moles[/tex]

Moles of O =[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{0.67g}{16g/mole}=0.042moles[/tex]

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For Pb = [tex]\frac{0.021}{0.021}=1[/tex]

For O = [tex]\frac{0.042}{0.021}=2[/tex]

The ratio of Pb O=  1: 2

Hence the empirical formula is [tex]PbO_2[/tex]

Answer:

Oxidation by FAD  

Explanation:

1. Oxidation by NAD⁺

Succinate ⇌ Fumarate + 2H⁺ + 2e⁻;                  E°´ =  -0.031 V  

NAD⁺ + 2H⁺ + 2e⁻ ⇌ NADH + H⁺;                      E°´ = -0.320 V

Succinate + NAD⁺ ⇌ Fumarate  + NADH + H⁺; E°' =  -0.351 V

2. Oxidation by FAD

Succinate ⇌ Fumarate + 2H⁺ + 2e⁻;        E°´ = -0.031 V  

FAD + 2H⁺ + 2e⁻ ⇌ FADH₂;                    E°´  = -0.219 V

Succinate + FADH₂ ⇌ Fumarate + FAD; E°' = -0.250 V

Neither reaction is energetically favourable, but FAD has a more positive half-cell potential.

FAD is the stronger oxidizing agent.

The oxidation by FAD has a more positive cell potential, so it is more favourable energetically.  

Answer:

Answer:

Joseph Henry.

Explanation:

Hello,

In this case, we define the accuracy based on the degree of deviation a measure has regarding the the true or expected value. In this case, the lower the difference, the more accurate the procedure. In such a way, for the two students, we compute the difference between the expected value and the obtained value:

[tex]Mary=2.300g/mL-2.226g/mL=0.074g/mL[/tex][tex]Joseph=2.335g/mL-2.300mL=0.035g/mL[/tex]

In such a way, since the difference is lower in Joseph's measure, we can say he is the most accurate.

Best regards.

Answer:

Formula: H2O Formula Weight: 18.02 CAS No.: 7732-18-5 Density: 1.000 g/mL at 3.98 °C(lit.)

Explanation:

Answer:

Pb(NO3)2(aq) + 2NaCl(aq) —> PbCl2(s) + 2NaNO3(aq)

Explanation:

When lead (II) nitrate, Pb(NO3)2 undergoes a double displacement reaction with aqueous sodium chloride, NaCl, the following products are obtained:

Pb(NO3)2(aq) + NaCl(aq) —>

Aqueous Pb(NO3)2 will dissociate in solution as follow:

Pb(NO3)2(aq) —> Pb2+(aq) + 2NO3-(aq)

On the other hand, aqueous NaCl will dissociate as follow:

NaCl(aq) —> Na+(aq) + Cl-(aq)

The double displacement reaction will take place as follow:

Pb(NO3)2(aq) + NaCl(aq) —>

Pb2+(aq) + 2NO3-(aq) + Na+(aq) + Cl-(aq) —> Pb2+(aq) Cl-(aq) + Na+(aq) 2NO3-(aq)

Pb(NO3)2(aq) + NaCl(aq) —> PbCl2(s) + NaNO3(aq)

We simply balance the equation by putting 2 in front of NaCl and 2 in front of NaNO3 as shown below:

Pb(NO3)2(aq) + 2NaCl(aq) —> PbCl2(s) + 2NaNO3(aq)

Answer:

D. BCl₃

Explanation:

BCl₃ molecular geometry is trigonal planar and it has a bond angle of 120°.

Hope that helps.

According to the molecular  geometry, BCl₃ has trigonal planar geometry and a bond angle of 120°.

Molecular geometry can be defined as a three -dimensional arrangement of atoms  which constitute the molecule.It includes parameters like bond length,bond angle  and torsional angles.

It influences many properties of molecules like reactivity,polarity color,magnetism .The molecular geometry can be determined by various spectroscopic methods and diffraction methods , some of which are infrared,microwave and Raman spectroscopy.

They provide information about geometry by taking into considerations the vibrational and rotational absorbance of a substance.Neutron and electron diffraction techniques provide information  about the distance between nuclei and electron density.

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Answer:

First, write a balanced equation of the reaction.

A hydrocarbon reacting with oxygen usually gives out carbon dioxide and water (combustion)

2C2H6 + 7O2 ---> 4CO2 + 6H2O

From the equation, we can see the mole ratio of ethane : oxygen is 2:7, meaning 2 moles of ethane reacts with 7 moles of oxygen.

If there's 1 mole of ethane gas, we need y moles of oxygen gas for complete reaction.

[tex]\frac{2}{7} =\frac{1}{y}[/tex]

y= 3.5 moles

Since 5 moles of oxygen is more than the required 3.5 moles, we can deduce oxygen gas is in excess, meaning ethane is limiting.

(You can get the same results too if you take y as ethane gas required).

The no. of moles of product produced ALWAYS depend on the no. of moles of the limiting reactant, since they are the ones which reacts completely.

So, from the equation, since the mole ratio of ethane : water = 2:6,

hence, (take the no. of moles of water produced as z),

[tex]\frac{2}{6} =\frac{1}{z} \\z= 3[/tex]

Therefore, 3 moles of water is produced.

Ethane is the limiting reagent in the given reaction. The number of moles of water produced from the reaction is 3 moles.

A limiting reagent can be defined as that reactant in the chemical reaction which is consumed first among the other reactants during the completion of a chemical reaction.

The limiting reagent is the reactant which decides the yield of the product when the quantity of the reactants is not taken in stoichiometry.

Given, chemical reaction of ethane and oxygen is:

[tex]C_2H_6 + \frac{7}{2} O_2 \longrightarrow 2CO_2 +3H_2O[/tex]

Given, the number of moles of ethane = 1 mol

The number of moles of oxygen = 5 mol

One more of ethane reacts with moles of oxygen = 3.5 mol

Therefore, ethane is the limiting reagent in this reaction as the oxygen is given in excess.

From the balanced equation, one mole of ethane produces moles of water equal to 3 moles.

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Answer:

HgO ⇒ Hg + 0.5 O₂

Explanation:

Let's consider the following equation corresponding to the decomposition of mercury (II) oxide.

mercury (II) oxide ⇒ mercury + oxygen

The corresponding compounds are:

The balanced chemical equation is:

HgO ⇒ Hg + 0.5 O₂

Answer:

The effective nuclear charge in a cesium atom is greatest in the 1s orbital

Explanation:

Effective nuclear charge (Zeff) is the positive nuclear charge that is experienced by an electron in an atom. It is affected by the shielding effect and penetration of electrons of the atoms.

The shielding effect is the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell. Innermost electrons shield the outermost electrons from the positive charge of the nucleus. The more electron shells there are, the greater the shielding effect experienced by the outermost electrons. and the more electron shielding an electron has, the lower the Zeff value.

Penetration is the ability of an electron to approach the nucleus. The closer the electron is to the nucleus, the higher the penetration. Electrons with higher penetration will shield outer electrons from the nucleus more effectively. The s orbital being closest to the nucleus has the highest penetration while the f orbital has the lowest penetration.

Cesium has an atomic number of 55 as well as nuclear charge of +55. It has 54 electrons in its filled 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s¹ shells and an outermost 6s electron. Based on the explanation above, the effective nuclear charge is greatest in the innermost 1s orbital and least in the outermost 6s orbital.

The electron in a cesium atom experience should be considered as the 1st orbital.

It is considered to be the positive nuclear charge i.e. experienced via the electron in an atom. It should be impacted via the effect of shielding and the penetration of the electron with respect to the atoms.

The electronic configuration of cesium should be like

[tex]1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^6 4d^10 5s^2 5p^6 6s^1[/tex]

Now

the electron which is in the innermost subshell will experience the highest effective nuclear charge and it should be 1s.

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Answer:

pH = 12.61

Explanation:

First of all, we determine, the milimoles of base:

0.120 M = mmoles / 300 mL

mmoles = 300 mL . 0120 M = 36 mmoles

Now, we determine the milimoles of acid:

0.200 M = mmoles / 100 mL

mmoles = 100 mL . 0.200M = 20 mmoles

This is the neutralization:

HCOOH    +     OH⁻         ⇄        HCOO⁻     +    H₂O

20 mmol       36 mmol             20 mmol

                    16 mmol

We have an excess of OH⁻, the ones from the NaOH and the ones that formed the salt NaHCOO, because this salt has this hydrolisis:

NaHCOO  →  Na⁺  +  HCOO⁻

HCOO⁻  +  H₂O  ⇄   HCOOH  +  OH⁻   Kb →  Kw / Ka = 5.55×10⁻¹¹

These contribution of OH⁻ to the solution is insignificant because the Kb is very small

So:  [OH⁻] =  16 mmol / 400 mL →  0.04 M

- log  [OH⁻]  = pOH →  1.39

pH = 14 - pOH → 12.61

Answer:

if a mixture of a given percentage or ratio strength is diluted to twice its original quantity, its active ingredient will be contained in twice as many parts of the whole, and its strength therefore will be reduced by one-half

Answer:

The ratio of the mass of an adult rhino to the mass of a small egret is

(1400 kg)/(0.76 kg) = 1842.11

The ratio of the mass of a proton to the mass of an electron is

1836.15

The two ratios are very similar, the ratio of the masses of the proton to the electron being slightly smaller.

Answer:

The pressure on Planet Venus is 88 times more that the pressure on earth at sea level.

Explanation:

Hello,

The pressure on the surface of planet Venus = 88.8atm.

The pressure at sea level on earth is 14.7psi.

To solve this question, we need to first convert the value of the pressure on the surface of Venus from atm to psi.

1 atm = 14.7psi

88atm = x psi

x = 1293.6psi

The pressure on the surface of planet Venus is 1293.6psi.

However the pressure on earth at sea level on earth is 14.7psi

The pressure on the surface of planet venus is 88 times more than the pressure on earth at sea level.

Answer:

1661μL of a 6M HCl you need to add

Explanation:

pH is defined as -log[H⁺] ([H⁺] =10^{-pH}), the initial and final concentrations of [H⁺] you need are:

Initial [H⁺] = 10^{-3.5} = 3.16x10⁻⁴M H⁺

Final [H⁺] = 10^{-1} = 0.1M H⁺

In moles, knowing volume of the solution is 0.1L:

Initial [H⁺] = 0.1L ₓ (3.16x10⁻⁴mol H⁺ / L) = 3.16x10⁻⁵moles H⁺

Final [H⁺] = 0.1L ₓ (0.1mol H⁺ / L) = 0.01 moles H⁺.

That means, moles of H⁺ you need to add to the solution is:

0.01mol - 3.16x10⁻⁵moles = 9.9684x10⁻³ moles of H⁺.

A solution of HCl dissociates in H⁺ and Cl⁻ ions, that means moles of HCl added are equal to moles of H⁺. As you need to add 9.9684x10⁻³ moles of H⁺ = 9.9684x10⁻³ moles of HCl:

9.9684x10⁻³ moles of HCl ₓ (1L / 6mol) = 1.6614x10⁻³L

In μL:

1.661x10⁻³L × (1x10⁶μL / 1L) =

Answer:

NaH(s) + H₂O(aq) ⇒ NaOH (aq) + H₂ (g)

Al(s) + Cl₂(g) ⇒ AlCl₃(s)

Explanation:

NaH - sodium hydride

H₂O - water

NaOH - sodium hydroxide

Al - aluminium

Cl₂ - Chlorine

AlCl₃ - aluminium chloride

Answer:

14.6 g

Explanation:

Fe₂O₃  +  3 C  →  2 Fe  +  3 CO₃

First, convert grams of Fe₂O₃ to moles.  The molar mass is 159.69 g/mol.

(64.6 g)/(159.69 g/mol) = 0.4045 mol

Now, use stoichiometry to convert moles of Fe₂O₃ to moles of C.  By looking at the chemical equation, you can see that for every 1 mole of Fe₂O₃, you need 3 moles of C.  Use this relationship.

(0.4045 mol Fe₂O₃) × (3 mol C/1 mol Fe₂O₃) = 1.214 mol C

Now, convert moles of C to grams.  The molar mass is 12.01 g/mol.

(1.214 mol C) × (12.01 g/mol) = 14.58 g

You need to use significant figures.

14.58 g ≈ 14.6 g

Answer:

2AlCl3 + 3Ca(OH)2 --> 2Al(OH)3 + 3CaCl2

Explanation:

aluminum chloride + calcium hydroxide --> aluminum hydroxide + calcium chloride

AlCl3 + Ca(OH)2 --> Al(OH)3 + CaCl2

Note: Al forms an ion of charge +3, Cl forms ion of charge -1, OH forms ion of -1, and Ca forms ions of charge +2. So when you combine 2 of these into ions, (must be one positive, one negative for ionic compounds), make sure the net charge at the end =0.

For example, Al ions have a charge of +3, so it needs 3 Cl- ions to eliminate the negative charge, so aluminium chloride is AlCl3.

Now balance the equation. make sure both sides have the equal no. of ions.

start with Cl. the reactant side has 3 Cl ions, while the product side has 2. So, the lowest common multiple is 6. Multiply AlCl3 by 2, and CaCl2 by 3 to get 6 Cl ions on each side.

2AlCl3 + Ca(OH)2 --> Al(OH)3 + 3CaCl2

Now the reactant side has 2 Al ions. So, multiply the Al(OH)3 on the product side by 2 to balance out Al ions.

2AlCl3 + Ca(OH)2 --> 2Al(OH)3 + 3CaCl2

Finally, the product side has 6 OH- ions, so multiply 3 on Ca(OH)2 from the reactant side to balance out the OH- ions.

2AlCl3 + 3Ca(OH)2 --> 2Al(OH)3 + 3CaCl2

Recount the ions to make sure it is correctly balanced! :)

Answer:

See explanation

Explanation:

a) Benzamide from benzene

For this synthesis, we have to start with the Friedel-Crafts reaction to produce Toluene. Then with a strong oxidant, we can produce benzoic acid. In the next step, we can use an esterification reaction to produce the methyl benzoate. Finally, we can use an acyl substitution reaction using ammonia to produce the benzamide.

b) From bromocyclohexane to cyclohexyl methyl ketone

In this case, we can start with a Grignard reaction. The first step is to produce the Grignard reagent with using magnesium. Then if we add acetaldehyde we can form an alcohol, 1-cyclohexylethan-1-ol. Finally, we can reduce the alcohol to produce cyclohexyl methyl ketone.

See figure 1

I hope it helps!

Answer:

Le Châtelier's principle states that when a chemical system at equilibrium is distributed by a change in  conditions, the equilibrium position will shift in a direction that tends to counteract  the change.

Therefore, when there is a change in pressure, the equilibrium will  counteract  the change by reducing/increasing the pressure through adjusting the no. of moles of gas.

Note: At constant temperature and volume the pressure of a gas is directly proportional to the number of moles of gas.

For example, when there's an increase in total pressure, the equilibrium position will shift to the side with a smaller no. of moles of gas so as to reduce the pressure.

Answer:

The equilibrium would shift to reduce the pressure change

Explanation:

Answer:

BF3

Explanation:

Hybridization can be defined as the mixing of two or more atomic pure orbitals. ( s, p ,  and d) to produce two or more hybrid atomic orbitals that are similar and identical in shape and energy e.g sp,sp²,sp³ ,sp³d, sp³d². Usually , the central atom of a covalent molecules or ion undergoes hybridization.

in BF3; Boron is the central atom. Here, A 2s  electron is excited from the ground state of boron ( 1s²2s²2p¹) to one empty orbitals of 2p.

The 2s orbital is then mixed with two orbitals of 2p to form three sp² hybrid orbitals tat are trigonally arranged in the plane in order to minimize repulsion . Each of the three hybrid orbitals overlaps with p-orbital of fluorine atom to form three bonds of equal strength and with bond angles of 120⁰.

                                  Energy                                                                  

B     ⇵  ║   ⇅  ║    ↑     ----------->    *B    ⇵ ║     ↑  ║     ↑  ║   ↑

       1s      2s         2p                              1s       2s           2p  

    Ground state                                        Excited State

The above shows an illustrative example of how electrons  move from the ground state to the excited state.

Answer:

Hello

you're answer should be E.HOCH2CH2OH

hope this answer is correct

The substance with the highest surface tension - e. HOCH2CH2OH.

Surface tension is the elastic tendency of a fluid, caused by the attraction of particles in the surface which makes it acquire the least surface area.  

Thus, The substance with the highest surface tension - e. HOCH2CH2OH.

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Answer:

density = 5.1g/m³

Explanation:

use ideal gas equation

Pv=nRT

28.26 x 3.51 = m/v x 0.08206 x 237

m/v = (28.26 x3.51)/(237 x 0.08206) = 5.1g/m³

Answer: The lowest possible melting point for engine coolant that is 26.1% ethylene glycol is [tex]-7.83^0C[/tex]

Explanation:

Depression in freezing point or melting point is given by:

[tex]\Delta T_f=i\times K_f\times m[/tex]

[tex]\Delta T_f=T_f^0-T_f=(0-T_f)^0C[/tex] = Depression in freezing point

i= vant hoff factor  = ( 1 for non electrolyte)

[tex]K_f[/tex]  = freezing point constant for water= [tex]1.86^0C/m[/tex]

m= molality

[tex]\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}[/tex]

Given : 26.1 g of ethylene glycol in 100 g of water

Weight of solvent (water)= 100 g = 0.1 kg     (1kg=1000g)

Molar mass of solute (ethylene glycol)  = 62 g/mol

Mass of  solute (ethylene glycol) added = 26.1 g

[tex](0-T_f)^0C=1\times 1.86\times \frac{26.1g}{62g/mol\times 0.1kg}[/tex]

[tex](0-T_f)^0C=7.83[/tex]

[tex]T_f=-7.83^0C[/tex]

Thus  the lowest possible melting point for engine coolant that is 26.1% ethylene glycol is [tex]-7.83^0C[/tex]

Answer:

Ecell = +0.25V

Explanation:

the half-cell reactions for a voltanic cell

cathode(reduction): 2H⁺(aq) + 2e⁻ ------- H₂(g)

anode(oxidation): 2AgCl(s) ------- 2Ag⁺(aq) + 2Cl⁻ + 2e⁻

we have the standard cell potential E⁺cell = 0.18V at 80C respectively

Q = [H⁺]/[Cl⁻]

sub for [H+] = 0.10M and [Cl-] = 1.5M

Q= 0.1M/1.5M

Q = 0.067

Ecell = E⁺cell - [tex]\frac{0.059}{n}[/tex] logQ

= 0.18 - [tex]\frac{0.056}{1}[/tex] log 0.067

0.18- 0.059(-1.174)

Ecell = +0.25V