What is the wavelength (in nm) of a photon required to excite an electron from n = 2 to n = 6 in a He⁺ ion? Submit an answer to three significant figures.

Answer:

Number of moles of hydrogen gas produced when 15.3 g of sodium reacts with water = 0.333 moles of hydrogen gas

Explanation:

The reaction between sodium metal and water is given by the chemical equation below:

2Na(s) + 2H₂O(l) ------> 2NaOH(aq) + H₂(g)

From the equation of reaction above, 2 moles of sodium reacts with 1 mole of water to produce 2 moles of sodium hydroxide and 1 mole of hydrogen  gas.

mole ratio of sodium and hydrogen gas is 2:1

molar mass of sodium =23 g/mol:

number of moles of sodium present in 15.3 g = mass/molar mass

number of moles of sodium present in 15.3 g = 15.3 g/ 23 g/mol = 0.665 moles

number of moles of hydrogen gas produced = 0.665 * 1/2 = 0.333 moles

Therefore, number of moles of hydrogen gas produced when 15.3 g of sodium reacts with water is 0.333 moles

Answer:B

Explanation:

The metal spoon is a better thermal conductor. Hence, option B is correct.

A thermal conductor is a material that allows the energy in the form of heat, to be transferred within the material, without any movement of the material itself.

Metals are good conductors. Laying on the metal handle of the metal cooking pot. It appears that the pot is sitting on top of a campfire.

Since metal is a good conductor of energy, the spoon gets hot because heat is transferred through the metal pot to its handle, and then to the metal spoon.

Hence, option B is correct.

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When electrons in an atom transition from a lower energy state to a higher energy state it has to absorb some energy in order to transition to the higher energy state.

When properly stimulated, the electrons in these materials move from lower energy levels to higher energy levels and occupy different orbits. Then, at some point, these high-energy electrons emit "extra" energy in the form of photons and return to their original energy levels.

Electrons jump to higher energy levels when excited by external energy gains such as B. Large heating, the presence of an electric field, or collision with another electron.

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Answer: D. 10,000 km = Exosphere; 690 km = Thermosphere; 85 km Mesosphere; 50 km = Stratosphere; 20 km = Troposphere

2. True

3. True

4. True

5. True

Answer:

Explanation:

If you look at an atom as a whole, it is electrically neutral and possesses no overall charge.  The nucleus consists of Protons and neutrons, Protons have a positive charge and neutrons have no charge on them.

Hence, the nucleus of an atom is positively charged and is generally surrounded by one or more electrons.

The electrons on the other hand have a negative charge on them.  

The sign convention for proton (+1), neutron(0) and electron(-1). The nucleus is very heavy but is very small compared to the overall size of an atom.            

An atom consists of a positively charged nucleus, surrounded by one or more negatively charged particles called electrons. The positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. I hope this helped.

No they are not, as climate is long term conditions for an area while weather is temporary

If you had a solution containing a mixture of magnesium, strontium, and barium, then we could separate these three elements using hydrogen sulphide, chromic acid and sulphuric acid.

To separate three elements from the solution, first we need to remove the magnesium element by adding hydrogen sulphide(H₂S) in the solution. It forms magnesium sulphide(MgS) as a precipitate and remaining ions are used for further separation.

To separate the barium element, we need to add chromic acid in the solution, which precipitate the barium chromate(BaCrO₄) from the solution.

In the remaining solution of strontium, we need to add sulphuric acid, which precipitates out the strontium sulphate(SrSO₄) as a product.

Therefore, to separate magnesium, strontium, and barium, we need to use hydrogen sulphide, chromic acid and sulphuric acid.

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The question requires us to calculate the energy, in joules (J), necessary to heat 83.5g of water from 26.7 °C to 75°C.

The heat energy (Q) can be calculated from the mass of the sample (m), its specific heat capacity of the substance (C) and temperature variation (ΔT), as given by the following equation:

Since the question did not provide a value for the specific heat capacity of water, we'll adopt the value 4.182 J/g.°C. Applying the values provided by the question, we can calculate the heat energy as:

Therefore, the heat energy necessary to heat the amount of water given grom 26.7 to 75°C is 1.69 x 10^4 J (or 16900 J).

Answer:

one is across

Explanation:

Linkage isomers are structural isomers that are formed when two or more ligands are bonded to a central metal atom through a common atom or group of atoms.

In the case of \([PtCl_3(SCN)]_2^-\), there are two possible linkage isomers:

\([PtCl_3(SCN)]_2^-\): In this isomer, the two Cl ligands are bonded to the same Pt center through a common SCN group. This forms a linear molecule with two Cl ligands on opposite ends and a Pt center in the middle.

\([PtCl_3(SCN)]_2^-\): In this isomer, the two Cl ligands are bonded to the same Pt center through a common N atom in the SCN group. This forms a square planar molecule with a central Pt atom and two Cl ligands bonded to it on opposite sides. Both of these linkage isomers have the same overall chemical formula  \([PtCl_3(SCN)]_2^-\), but they have different structural arrangements of the ligands and metal atoms.  

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\( - 34 {}^{15} \)

Answer:

Option 1, Soil erosion

Answer:

Heat = 3138J

Explanation:

In the system, the sample of Copper is releasing heat that produce the increasing in the temperature of water.

Using the equation of calorimeter, we can find the heat released for the sample of copper (The same that is absorbed for the water):

Q = C×m×ΔT

Where Q is heat, C is specific heat (For water: 4.184J/molK), m is the mass of water (50g) and ΔT is change in temperature of water (40°C-25°C = 15°C)

Replacing:

Q = 4.184J/molK×50g×15°C

Q = 3138J is the heat released for the sample of Copper (The same absorbed for the water).

Answer:

heat=3138j

Explanation:

In the system, the sample of Copper is releasing heat that produce the increasing in the temperature of water.

Using the equation of calorimeter, we can find the heat released for the sample of copper (The same that is absorbed for the water):

Q = C×m×ΔT

Where Q is heat, C is specific heat (For water: 4.184J/molK), m is the mass of water (50g) and ΔT is change in temperature of water (40°C-25°C = 15°C)

Replacing:

Q = 4.184J/molK×50g×15°C

Q = 3138J is the heat released for the sample of Copper (The same absorbed for the water).

The molecular mass of the unknown gas is approximately 43.6 g/mol.

To determine the molecular mass of the unknown gas, we can use the ideal gas law equation: PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.

First, let's convert the given mass of the gas to moles. The molar mass (M) of a substance is defined as the mass of one mole of that substance. Therefore, the number of moles (n) can be calculated using the formula n = m/M, where m is the mass of the sample and M is the molecular mass of the gas.

Given that the mass of the sample is 23.3g and the volume is 12.01 L, we can use the ideal gas law to calculate the number of moles:

PV = nRT

n = PV / RT

Plugging in the values:

n = (12.01 L) × (1 atm) / [(0.0821 L·atm/(mol·K)) × (273.15 K)]

Simplifying the equation:

n = (12.01 L) × (1 atm) / (22.41 L·atm/(mol·K))

n = 0.535 mol

Now, we can calculate the molecular mass (M):

M = m / n

M = 23.3g / 0.535 mol

M ≈ 43.6 g/mol

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The statement that is false regarding the chemical grooming of pyruvate is "each pyruvate molecule has a CO2 added and then joins with an NADH.

Pyruvate is the end product of glycolysis that further undergoes chemical grooming in the presence of oxygen to produce ATP. The complete oxidation of glucose produces a total of 36-38 ATPs per molecule.

Pyruvate is oxidized to produce Acetyl-CoA. During this process, the carboxyl group of pyruvate is removed and given off as CO2. This is known as decarboxylation.

The remaining 2-carbon molecule is then oxidized by the removal of electrons by the NAD+ which is reduced to NADH. This is called oxidative decarboxylation, and its purpose is to prepare the substrate for energy production.

The correct statement regarding the chemical grooming of pyruvate is, "Each pyruvate molecule loses a CO2 molecule and then joins with a coenzyme A to form acetyl-CoA, producing an NADH molecule."

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Answer:

D: fussion

Explanation:

The process called nuclear fussion.

for example, four hydrogen atoms combine in a nuclear fussion reaction to form one helium atom.

The density of the gas is 0.639 g/L. The molar mass of the gas is 153.5 g/mol.

Given parameters:Mass of the gas = 1.95 g

Volume of the flask = 3.05 LTemperature of the gas = 57°C = 330 KPressure of the gas = 1.05 atm = 106.625 kPa (1 atm = 101.325 kPa)Let's use the Ideal Gas Law formula:PV = nRT where P = pressure of the gas V = volume of the gas n = number of moles of the gasR = gas constant = 8.314 J/mol.KT = temperature of the gasLet's solve for n:n = (PV)/(RT)n = (106.625 kPa × 3.05 L) / (8.314 J/mol.K × 330 K)n = 0.0127 molThe mass and the number of moles of the gas are given:Mass of the gas = 1.95 gn = 0.0127 mol

Let's solve for the density of the gas using the formula:density = mass / volumedensity = 1.95 g / 3.05 Ldensity = 0.639 g/L (rounded to three significant figures)Let's solve for the molar mass of the gas using the formula:molar mass = mass / number of molesmolar mass = 1.95 g / 0.0127 molmolar mass = 153.5 g/mol (rounded to three significant figures)Answer: The density of the gas is 0.639 g/L. The molar mass of the gas is 153.5 g/mol.

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The change in temperature during a chemical reaction can provide information about whether the reaction is exothermic (releases heat) or endothermic (absorbs heat).

The change in temperature of a chemical reaction is often an important indicator of the energy absorbed or released during the reaction. In this case, we have two different reactions occurring in two separate beakers, with different temperature changes.

In beaker A, the temperature increases from 25 to 40 degrees. This suggests that the reaction in beaker A is exothermic, meaning that it releases heat to the surroundings. The reaction is giving off energy, which is reflected in the temperature increase of the beaker.

In beaker B, the temperature decreases from 25 to 20 degrees. This suggests that the reaction in beaker B is endothermic, meaning that it absorbs heat from the surroundings. The reaction is taking in energy, which is reflected in the temperature decrease of the beaker.

It's worth noting that the temperature change alone is not sufficient to determine the nature of the reaction (i.e. exothermic or endothermic). Other factors, such as the reaction equation and the properties of the reactants and products, must also be considered. However, temperature change can be a useful clue in identifying the energy changes that occur during a chemical reaction.

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If 250 mL of methane (CH4) effuses through a small hole in 48 s, the time required for the same volume of helium to pass through the hole is approximately 96 s.

The effusion rate of a gas is inversely proportional to the square root of its molar mass, according to Graham's law of effusion. In this case, we need to compare the effusion rates of methane and helium.

Since the volume is constant, we can use the ratio of their times of effusion.

Let's assume the molar mass of methane (CH4) is M1 and the molar mass of helium (He) is M2. According to Graham's law, the ratio of the effusion times is given by:

(time for methane) / (time for helium) = √(M2 / M1)

Given that the time for methane is 48 s, we need to find the time for helium. Rearranging the equation, we have:

(time for helium) = (time for methane) / √(M2 / M1)

By substituting the molar masses of methane (16.04 g/mol) and helium (4.00 g/mol), we can calculate:

(time for helium) = 48 s / √(4.00 g/mol / 16.04 g/mol)

(time for helium) = 48 s / √(0.25)

(time for helium) = 48 s / 0.5

(time for helium) = 96 s

Therefore, the time required for the same volume of helium to pass through the hole is approximately 96 seconds.

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Answer:

A

Explanation:

Answer:

It is A!

Explanation:

Answer:

Potential energy to kinectic energy

Explanation:

To determine the exact value of pK2 in this case, we can use the relationship between pH and pK, which states that the pH of a solution is equal to the pK of the acid with the lowest concentration when the acid and its conjugate base are in equilibrium.

Here, we know that the pH of the solution dropped from 8.00 to 3.20 after the addition of HCl. We can assume that the second group is now in the acid form since we know that the first ionizable group has a pK of 3.8, and the second group (pK2) is between 7 and 10, we can assume that the second group is now in the acid form.

We can use the relationship between pH and pK to calculate the exact value of pK2:

pH = pK2 = pKw / [H+] = 14.00 - log([H+])

3.20 = 14.00 - log([H+])

Solving for [H+], we find that [H+] = 1.0 x 10^-3.2

Now we can find the value of pK2 as:

pK2 = 14.00 - log(1.0 x 10^-3.2) = 14.00 - (-3.2) = 14.00 + 3.2 = 17.2

Therefore, the exact value of pK2 is 17.2.

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Answer:

THANKSSSS

Explanation:

Answer:

Your A Literal Life Saver Thx

Explanation:

According to the equation for the reaction, if the number of moles of reactants is halved, the number of moles of H₂O (l) produced in the reaction is halved as well.

A titration is a procedure in volumetric analysis in which a given volume of a solution of a known concentration is added to a given volume of a solution of an unknown concentration to determine the unknown concentration.

The moles of the substances that reacted as given in the equation of the reaction are used to determine the unknown concentration.

The equation of the given reaction is given below:

HCl + NaOH ---> NaCl + H₂O

1 mole of HCl reacts with 1 mole of NaOH to form 1 mole of water.

Hence, halving the moles of reactants would halve the mole of water formed.

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The energy needed is the energy that changes. The electron in a hydrogen atom is initially assumed to be in the ground state with n=1. The energy of the electron in its ground state is therefore 13.6 eV.

As a result, 12.75eV of the energy is needed to transfer electrons from the ground state to the third excited state. The 4th and 5th ionisation the energies differ significantly from one another. The fourth electron is attracted to the nucleus atom considerably less strongly than the fifth electron because it is in an inner main shell that is closer to the nucleus.

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Answer

47.73 g CuO

Explanation

Given:

Chemical equation: 3CuO+ 2H3PO4 = Cu3(PO4)2 + 3H20

mass of orthophosphate acid (Cu3(PO4)2) = 39.2 g

Required: The mass of CuO

Solution:

Second method:

Step 1: Find the moles of H3PO4

n = m/M where m is the mass and M is the molar mass of H3PO4

n = 39.2g/97.994g.mol^-1

n = 0.400 mol

Step 2: Use the stoichiometry to find the moles of CuO

The molar ratio between CuO and H3PO4 is 3:2

Therefore the moles of CuO = 0.400 mol x (3/2) = 0.600 mol

Step 3: Find the mass of CuO, now that we have moles

m = n x M m is the mass, n is the moles and M is the molar mass

m = 0.600 mol x 79,545 g/mol

m = 47.73 g

Answer:

C₂H6

Explanation:

Among the given options, the formula A) C₂H6 represents a hydrocarbon (specifically, ethane). Option A

A hydrocarbon is a compound that consists of only carbon and hydrogen atoms. It is important to identify the formula that represents a hydrocarbon among the given options:

A) C₂H6: This formula represents ethane, which is a hydrocarbon. Ethane consists of two carbon atoms bonded together with single bonds and six hydrogen atoms.

B) C₂H5OH: This formula represents ethanol, which is not a hydrocarbon. Ethanol contains a hydroxyl group (-OH), indicating the presence of oxygen in addition to carbon and hydrogen atoms. It is an alcohol, not a hydrocarbon.

C) C₂H5Cl: This formula represents ethyl chloride, which is not a hydrocarbon. Ethyl chloride contains a chlorine atom (Cl) in addition to carbon and hydrogen atoms. It is a haloalkane, not a hydrocarbon.

D) C₂H6O: This formula represents ethanol, which, as mentioned before, is not a hydrocarbon. Ethanol contains an oxygen atom (O) in addition to carbon and hydrogen atoms. It is an alcohol, not a hydrocarbon.

Among the given options, the formula A) C₂H6 represents a hydrocarbon (specifically, ethane). It consists only of carbon and hydrogen atoms, making it a suitable representation of a hydrocarbon.

In summary, the formula C₂H6 (option A) represents a hydrocarbon, while the other options contain additional elements (oxygen or chlorine) that make them non-hydrocarbon compounds. Option A

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Answer:

if i consider this reaction

Fe2O3+ 3CO---》2Fe+ 3CO2

so let's calculate first moles of Fe2O3 i.e. = 256/159.69= 1.6 moles

So the one moles of Fe2O3 is forming three moles of CO2

hence 1.6 moles will form 4.8 moles of CO2

one mole of CO2 is 44 g so 4.8 moles of Co2 is 44×4.8= 211.2 g

so the conclusion is 211.2 g of CO2 can be produced from 256 g Fe2O3!!

i d k it's right or wrong but i tried my best :)

Answer:

True

Explanation: