What is the phase change from solid to gas?
O A. Condensation
O B. Sublimation
O C. Freezing
O D. Vaporization

Answer:

80.8%

Explanation:

Let's consider the following balanced equation.

4 Al(s) + 3 O₂(g) → 2 Al₂O₃(s)

The mass obtained of Al₂O₃ (experimental yield) is 84.0 g. The theoretical yield of Al₂O₃ is 104 g. We can calculate the percent yield of Al₂O₃ using the following expression.

%yield = (experimental yield / theoretical yield) × 100%

%yield = (84.0 g / 104 g) × 100% = 80.8%

Answer:

Percent Yield = 80.8%

Explanation:

We can find the percent yield of a reaction using the equation:

Percent yield = Actual yield (g) / Theoretical Yield (g) * 100

Where Actual yield is the amount of product produced (84.0g)

And theoretical yield is the mass produced assuming a 100% of product (104.0g)

Replacing the computed values:

Percent yield = 84.0g / 104.0g * 100

Percent Yield = 80.8%

Answer:

(A) 1.962x10^-10 M solubility in pure water

(B) 4.0 x 10^-33 M solubility

(C) 4.0 x 10^-27 M solubility

Explanation:

(A) Fe(OH)3 would give (Fe3+) and (3OH-)

Ksp = [Fe^3+][OH-]^3 = 4.0 x 10^-38

Let y = [Fe^3+]

Let 3y = [OH-]

4x10^-38 = (y)(3y)^3

4x10^-38 = 27y^4

y^4 = 4x10^-38 ÷ 27

y^4 = 1.481 x 10^-39

y = 1.962x10^-10 M solubility in pure water

(B) pH = 5.0

5.0 = - log [OH-]

-5.0 = log [OH-]

[OH-] = 10^-5.0 =  1.0 x 10^-5 M

So, Ksp = [Fe^3+][OH-]^3 = 4.0 x 10^-38

[Fe^3+][1.0 x 10^-5] = 4.0 x 10^-38

[Fe^3+] = 4.0 x 10^-38 ÷ 1.0 x 10^-5

= 4.0 x 10^-33 M solubility

(C) pH = 11.0

11.0 = - log [OH-]

-11.0 = log [OH-]

[OH-] = 10^-11.0 =  1.0 x 10^-11 M

So, Ksp = [Fe^3+][OH-]^3 = 4.0 x 10^-38

[Fe^3+][1.0 x 10^-11] = 4.0 x 10^-38

[Fe^3+] = 4.0 x 10^-38 ÷ 1.0 x 10^-11

= 4.0 x 10^-27 M solubility

In a flame test electrons are excited to higher energy levels and their emissions are observed. Therefore, option A is correct.

The flame test is used to visually identify the identity of an unknown metal or metalloid ion based on the properties color the salt turns in the flame of a bunsen burner.

The color of light emitted depends on the energy emitted by an electron returning to its original state.

The flame's heat converts metal ions into atoms, which become excited and emit visible light. In a flame test electrons are excited to higher energy levels and their emissions are observed.

Thus, option A is correct.

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Answer:

(a) The potential near its surface is 45 * 10^6 V.

(b) The distance from which its center is the potential 1.00 MV is 45 m.

(c) Its energy in MeV when the atom is at the distance found in part b is 132 MeV.

Explanation:

Note: This question is not complete. The complete question is therefore provided before answering the question.

A research Van de Graaff generator has a 2.00-m diameter metal sphere with a charge of 5.00 mC on it. (a) What is the potential near its surface?

(b) At what distance from its center is the potential 1.00 MV?

(c) An oxygen atom with three missing electrons is released near the Van de Graaff generator. What is its energy in MeV when the atom is at the distance found in part b?

The explanation of the answer is now provided as follows:

(a) What is the potential near its surface?

Q = Charge on the generator = 5 mC = 5 * 10^(-3)C

r = Sphere radius = 2 / 2 = 1 m

k = Constant of the electric force = 9 * 10^(9) N . m^2 / C^2

Therefore, the electric potential of a point charge can be calculated as follows:

V = kQ / r

V = (9 * 10^9 * 5 * 10^(-3)) / 1 = 45 * 10^6 V

Therefore, the potential near its surface is 45 * 10^6 V.

(b) At what distance from its center is the potential 1.00 MV?

This implies the distance where the potential is 1 MV.

Since the electric potential of a point charge is as follows:

V = kQ / r

Therefore, we can solve for r and estimate it as follows:

R = kQ / V = (9 * 10^9 * 5 * 10^(-3)) / 1 * 10^6 = 45 m

Therefore, the distance from which its center is the potential 1.00 MV is 45 m.

(c) An oxygen atom with three missing electrons is released near the Van de Graaff generator. What is its energy in MeV when the atom is at the distance found in part b?

The link between the potential difference and electrical potential energy can be stated as follows:

ΔV = ΔU / q

Therefore, we have:

ΔU = qΔV = q(Va - Vb) = 3 * (45 – 1) = 132 MeV

Therefore, its energy in MeV when the atom is at the distance found in part b is 132 MeV.

Answer:

a.

[tex]Keq=\frac{[HCO_3^-][OH^-]}{[CO_3^{2-}]}[/tex]

b.

[tex]Keq=[O_2]^3[/tex]

c.

[tex]Keq=\frac{[H_3O^+][F^-]}{[HF]}[/tex]

d.

[tex]Keq=\frac{[NH_4^+][OH^-]}{[NH_3]}[/tex]

Explanation:

Hello there!

In this case, for the attached reactions, it turns out possible for us to write the equilibrium expressions by knowing any liquid or solid would be not-included in the equilibrium expression as shown below, with the general form products/reactants:

a.

[tex]Keq=\frac{[HCO_3^-][OH^-]}{[CO_3^{2-}]}[/tex]

b.

[tex]Keq=[O_2]^3[/tex]

c.

[tex]Keq=\frac{[H_3O^+][F^-]}{[HF]}[/tex]

d.

[tex]Keq=\frac{[NH_4^+][OH^-]}{[NH_3]}[/tex]

Regards!

Answer:

The maximum mass of water that could be produced by the chemical reaction=0.441g

Explanation:

We are given that

Given mass of HBr=5.7 g

Given mass of sodium hydroxide=0.980 g

Molar mass of HBr=80.9 g/ Mole

Molar mass of NaOH=40 g/mole

Molar mass of H2O=18 g/mole

Reaction

[tex]HBr+NaOH\rightarrow H_2O+NaBr[/tex]

Number of moles=[tex]\frac{given\;mass}{molar\;mass}[/tex]

Using the formula

Number of moles of HBr=[tex]\frac{5.7}{80.9}=0.0705 moles[/tex]

Number of moles of NaOH=[tex]\frac{0.980}{40}=0.0245moles[/tex]

Hydrogen bromide is in a great excess and the amount of water produced.

Therefore,

Number of moles of water, n(H2O)=Number of moles of NaOH=0.0245moles

Now,

Mass of water=[tex]n(H_2O)\times Molar\;mass\;of\;water[/tex]

Mass of water=[tex]0.0245moles\times 18=0.441g[/tex]

Hence, the maximum mass of water that could be produced by the chemical reaction=0.441g

The question is incomplete, the complete question is:

A chemist measures the amount of iodine solid produced during an experiment. He finds that 8.31 g of iodine solid is produced. Calculate the number of moles of iodine solid produced. Round your answer to the correct number of significant digits.

Answer: The number of moles of solid iodine produced is 0.0327 moles

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass.  The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

Given mass of solid iodine = 8.31 g

Molar mass of solid iodine = 253.8089 g/mol

Plugging values in equation 1:

[tex]\text{Moles of solid iodine}=\frac{8.31g}{253.8089g/mol}=0.0327mol[/tex]

Hence, the number of moles of solid iodine produced is 0.0327 moles

Answer:

To 318.18 mL would you need to dilute 20.0 mL of a 1.40 M solution of LiCN to make a 0.0880 M solution of LiCN

Explanation:

Dilution is the reduction of the concentration of a chemical in a solution and consists simply of adding more solvent.

In a dilution the amount of solute does not vary. But as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

In a solution it is fulfilled:

Ci* Vi = Cf* Vf

where:

In this case:

Replacing:

1.40 M* 20 mL= 0.088 M* Vf

Solving:

[tex]Vf=\frac{1.40 M* 20 mL}{0.088 M}[/tex]

Vf= 318.18 mL

To 318.18 mL would you need to dilute 20.0 mL of a 1.40 M solution of LiCN to make a 0.0880 M solution of LiCN

Explanation:

Answer:

d

Explanation:

Answer:

The set of quantum numbers is not valid

Explanation:

There are four sets of quantum numbers;

1) Principal quantum number (n) which takes on integer values from n = 1,2,3 .......

2) Azimuthal quantum number (l) which takes on values 1, 2, ....(n - 1)

3) Magnetic quantum numbers (ml) which takes on values from (-l) to (+l)

4) spin quantum number (ms) which takes on values of ±1/2.

From the above, we can see that m can not have a value of 3 when l =2 because m has values between (-l) to (+l). Thus, the sets of quantum numbers is not valid.

Answer:

0.554 kg

Explanation:

We want to find the amount of kilograms of fluorine that will be released into the air over 6 months.

Let's convert to weeks to get;

6 × 4 = 24 weeks

Let's find Mass leak rate of fluorine from the formula;

Mass leak rate = (fluorine mass in freon/molar mass of freon) × leak rate

Molar mass of freon = ((12 × 2) + (1 × 2) + (19 × 3) + (35.5)) = 118.5 g/mol

Thus;

Mass leak rate = ((19 × 3)/(118.5)) × 47.97 = 23.074 g/week

Total fluorine leaked in 6 months = 24 × 23.074 = 553.776 g = 0.554 kg

Answer:

unsaturated fats, which are liquid at room temperature,are different from saturated fat because they contain one or more double bonds and fewer hydrogen atoms on their carbon chain.

Answer:

no reaction occurs .that is no product

Answer:

Tin + silver trioxonitrate V -------->Tin IV nitrate + silver

Explanation:

The term word equation refers to an equation in which the reactants and products are written in words rather than chemical symbols.

Note than tin is above silver in the electrochemical series hence silver will be displaced by tin as follows;

Tin + silver trioxonitrate V -------->Tin IV nitrate + silver

Answer:

the result for the following are (a) P is directly proportional to n

(b) V is directly proportional to T (c) P is directly proportional to T (d) T is inversly proportional to V (e) P is inversely proportional to V

Answer:

A. the Law of Multiple Properties

Answer:

A. the law of multiple proportions

Answer:

63.05% of MgCO3.3H2O by mass

Explanation:

of MgCO3.3H2O in the mixture?

The difference in masses after heating the mixture = Mass of water. With the mass of water we can find its moles and the moles and mass of MgCO3.3H2O to find the mass percent as follows:

Mass water:

3.883g - 2.927g = 0.956g water

Moles water -18.01g/mol-

0.956g water * (1mol/18.01g) = 0.05308 moles H2O.

Moles MgCO3.3H2O:

0.05308 moles H2O * (1mol MgCO3.3H2O / 3mol H2O) =

0.01769 moles MgCO3.3H2O

Mass MgCO3.3H2O -Molar mass: 138.3597g/mol-

0.01769 moles MgCO3.3H2O * (138.3597g/mol) = 2.448g MgCO3.3H2O

Mass percent:

2.448g MgCO3.3H2O / 3.883g Mixture * 100 =

Answer:

a)calculated molarity of NaOH would be lower

b) calculated molarity of NaOH would be lower

c) calculated molarity of NaOH would be lower

d) calculated molarity of NaOH would be unaffected

Explanation:

Let us recall that the reaction of NaOH and HCl is as follows;

NaOH(aq) + HCl(aq) ----> NaCl(aq) + H2O(l)

Since the reaction is 1:1, when the number of moles of HCl reacting with NaOH is low due to dilution, the calculated molarity of NaOH also becomes less than it's accurate value.

When 40mL of water is added to the titration flask rather than 25ml of water, the acid is more dilute hence less number of moles of acid than necessary reacts with the base thereby yielding a less than accurate value of the molarity of NaOH.

If the burette wet with water is not rinsed with NaOH solution, the concentration of the NaOH in the burette decreases due to dilution with water and a less than accuracy value is calculated for the molarity of NaOH.

If five drops of phenolphthalein is used instead of one or two drops, there is no qualms since enough phenolphthalein may be added to ensure that a sharp end point is obtained.

Answer:

1. Its formation requires very strong updrafts = a. Hail

2. Its formation requires falling through a layer of above-freezing air = d. Freezing Rain

3. Precipitation from cumuliform clouds is typically of this nature = c. Shower

4. Precipitation from stratus clouds is typically of this nature = Drizzle

Explanation:

Hail formation requires very strong updrafts, these updrafts are the upward moving air created in a thunderstorm. This period of noticeable thunderstorms creates hails.

Freezing rain requires the presence of warm air, it requires falling through a layer of above-freezing air to the colder air below to produce an ice coating on anything it drops on.

Showers are produced by cumuliform clouds which look like cotton balls. Since cumuliform clouds precipitate too, these clouds can have fluctuating rain in a day in the form of showers.

Drizzle which raises low visibility is considered a type of liquid precipitation since it also falls from a cloud. Drizzle which is obviously smaller in diameter when compared to that of raindrops, however, is common with stratus clouds.

Answer:

The best existing methods of control—artemisinin-based drug treatment and insect control with chemical sprays and treated bednets—can reduce the burden of disease substantially, and can even eliminate the disease in some regions,

hope this will help you more

Answer:

Explanation:

The density of pure water is 1 gram per 1 milliliter or one cubic cm. By knowing the density of water we can use it in dilution equations or to calculate the specific gravity of other solutions.

It can also help us determine what other substances are made of using the water displacement experiment. This is done by observing how much water is displaced when an object is submerged in the water. As long as you know the density of the water, the mass of the object being submerged and the volume of increase you can calculate the density of the object.

This was done by the great Archimedes in discovering what composed the kings crown.

Answer:

A molecular mass is mass on the substance  and mole is a unit of substance such as atoms and electrons.

Explanation:

Molecular mass: A molecule's molecular mass is equal to the sum of all of the atoms' individual atomic masses. It establishes the molecular mass of a single unit.

Example:

Molecular mass of O2 = 32 atomic mass units

Mole: A mole is [tex]6.02214076 x 10^2^3[/tex]of any chemical unit, including atoms, molecules, ions, and others. Due to the large number of atoms, molecules, or other components that make up any material, the mole is a useful measure to utilize. The initial definition of the mole was the number of atoms in 12 grams of carbon-12.

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Answer:

60 q

Explanation:

The conversion factor is 100; so 1 quintal = 100 kilograms. In other words, the value in q multiply by 100 to get a value in kg.

Answer:

2s2 2p5

Rb < Sr< Sn< Te<I

Explanation:

Electron affinity is the ability of an atom to accept electrons to form negative ions.

Electron affinity is a periodic trend that decreases down the group but increases across the period.

This accounts for the trends observed in the answer. The atom having the electronic configuration, 2s2 2p5 must be a halogen and it exhibits the highest value of electron affinity.

Also, since electron affinity increases across the period, the electron affinities of the elements increases. Therefore, the arrangement of atoms as shown in the answer depends on increasing electron affinity.

Answer:

Explanation:

B

Answer:

1.02 Hz

Explanation:

frequency= (1/t) = (1/0.98) = 1.02 hz

Answer:

The produced salt is calcium chloride, CaCl₂, whose cation, Ca²⁺, is the conjugate acid of the base and the anion, Cl⁻ the conjugate base of the acid.

Explanation:

Hello there!

In this case, according to the given information, it turns out firstly necessary for us to set up the chemical equation between calcium hydroxide and hydrochloric acid:

[tex]2HCl+Ca(OH)_2\rightarrow CaCl_2+2H_2O[/tex]

It means that the produced salt is calcium chloride, CaCl₂, whose cation, Ca²⁺, is the conjugate acid of the base and the anion, Cl⁻ the conjugate base of the acid.

Regard"

Answer:

0.518 g

Explanation:

Step 1: Write the balanced equation

3 CaCl₂ + 2 H₃PO₄ ⇒ Ca₃(PO₄)₂ + 6 HCl

Step 2: Calculate the moles corresponding to 0.555 g of CaCl₂

The molar mass of CaCl₂ is 110.98 g/mol.

0.555 g × 1 mol/110.98 g = 5.00 × 10⁻³ mol

Step 3: Calculate the moles of Ca₃(PO₄)₂ produced

5.00 × 10⁻³ mol CaCl₂ × 1 mol Ca₃(PO₄)₂/3 mol CaCl₂ = 1.67 × 10⁻³ mol Ca₃(PO₄)₂

Step 4: Calculate the mass corresponding to 1.67 × 10⁻³ moles of Ca₃(PO₄)₂

The molar mass of Ca₃(PO₄)₂ is 310.18 g/mol.

1.67 × 10⁻³ mol × 310.18 g/mol = 0.518 g

Answer: If a hydrogen atom and a helium atom have the same kinetic energy then the wavelength of the hydrogen atom will be roughly equal to the wavelength of the helium atom.

Explanation:

The relation between energy and wavelength is as follows.

[tex]E = \frac{hc}{\lambda}\\[/tex]

This means that energy is inversely proportional to wavelength.

As it is given that energy of a hydrogen atom and a helium atom is same.

Let us assume that [tex]E_{hydrogen} = E_{helium} = E'[/tex]. Hence, relation between their wavelengths will be calculated as follows.

[tex]E_{hydrogen} = \frac{hc}{\lambda_{hydrogen}}[/tex]    ... (1)

[tex]E_{helium} = \frac{hc}{\lambda_{helium}}[/tex]         ... (2)

Equating the equations (1) and (2) as follows.

[tex]E_{hydrogen} = E_{helium} = E'\\\frac{hc}{\lambda_{hydrogen}} = \frac{hc}{\lambda_{helium}} = E'\\\lambda_{helium} = \lambda_{hydrogen} = E'[/tex]

Thus, we can conclude that if a hydrogen atom and a helium atom have the same kinetic energy then the wavelength of the hydrogen atom will be roughly equal to the wavelength of the helium atom.