I need help with the practice question at the bottom. Thank you.

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:be careful and relax

Explanation:

Answer:

Hahaha be careful and relax

Explanation:

here is your answer. Hope it helps

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:

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:

(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

Answer:

A. the Law of Multiple Properties

Answer:

A. the law of multiple proportions

Answer: 178mph

Explanation:

From the question given, we are informed that the speed limit on parts of the German autobahn was once set at 286 kilometers per hour (km/h). Based on the information, the speed limit in miles per hour will then be:

= 286km/h × 1000m/1km × 1mi/1609m

= 178miles per hour

Therefore, the speed limit is 178mph.

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:

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:

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

[tex] {\bold{\red{\huge{\mathbb{QUESTION}}}}} [/tex]

Draw the structural model for methanal (using C and H and O).

[tex] \huge\mathbb{\red A \pink{N}\purple{S} \blue{W} \orange{ER}}[/tex]

First place the C and then make a double bonded O atom with it then fill H to complete all valence spaces

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:

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%

Explanation:

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.

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

Answer:

1.02 Hz

Explanation:

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

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:

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. Na+ is pH neutral

b. Ni2+ = weak acid

c. NH4+ = Weak acid

Explanation:

To know the nature of the cation we need to find the nature of its conjugate base.

If the conjugate base of the ion is a strong base, the ion is neutral.

If the conjugate base is a weak base, the ion is a weak acid:

a. Conjugate base Na+ = NaOH

Sodium hydroxide is a strong base:

Na+ is pH neutral

b. Conjugate base Ni²⁺: Ni(OH)2 is a weak base because is not completely soluble in water. That means:

Ni2+ = weak acid

c. Conjugate base NH4+: NH4OH. Weak base:

NH4+ = Weak acid

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

Answer:

sodium ions and chloride ions

chloride ion

sodium ion

Explanation:

Ionic substances are composed of ions. When you dissolve an Ionic substance in water, the ions that compose the substance together with water molecules are present in solution.

Hence, when sodium chloride is dissolved in water, sodium ions and chloride ions are released in solution.

Water has a dipole moment. Hence, the chloride ions are attracted to hydrogen (the positive end of the dipole) while sodium ions are attracted to oxygen (the negative end of the dipole).

This is how the solid is dissolved in water.

When sodium chloride, NaCl , dissolves in water, the solution contains sodium and chloride ions in addition to the water solvent. The partial charges in water help dissolve the compound as the hydrogen end of water is attracted to the chloride ions and the oxygen end is attracted to the sodium ions.

Those molecules in which positive ion as well as negative ion is present, will show solubility in water.

Sodium chloride (NaCl) is an ionic compound, which dissociates into sodium ion and chloride ion in the water. As in the water H⁺ ions are present which get attracted towards the chloride ions (Cl⁻) and hydroxide ion (OH⁻ ion) get attracted towards the sodium ions (Na⁺) and show complete dissolution.

Hence correct answers are sodium and chloride ions, chloride ion and sodium ion.

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Based on the calculations, the Gibbs's free energy for this chemical reaction is equal to -1,680.906 kJ/mol.

Given the following data:

Gibbs's free energy simply refers to the quantity of energy that is associated with a particular chemical reaction.

Mathematically, the Gibbs's free energy for this chemical reaction can be calculated by using this formula:

ΔG° = ΔH° - ΔS°

Substituting the given parameters into the formula, we have;

ΔG° = -1652 × 10³ - (298 × 0.097)

ΔG° = -1652 × 10³ - 28.906

ΔG° = -1,680.906 kJ/mol.

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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:

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:

d

Explanation:

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:

Hope it is helpful to you