My work gave me 12.3. Please walk me through how you would approach this problem so I can see where I went wrong.

Rutherford's models

There are known as the region where electrons are found especially in the nucleus.

According to the five basic atomic models which have contributed to the structure of the atom itself, the Rutherford's models of the atom include a structure that is mostly made of empty space compared to thomson that proposed the plum pudding model of the atom

An empirical formula is the simplest form of a formula, that is, the subscripts are simplified.

Therefore, the answer is H2O2 because it's not the simplest form.

Answer:

Explanation:

Here, we want to get the number of moles of nitrogen

Mathematically:

3.21 * 10^54 atoms of nitrogen will contain:

The chemical formula of potassium hydroxide is KOH.

The chemical formula of hydrobromic acid is HBr.

The chemical formula of potassium bromide is KBr.

The chemical formula of water is H2O.

The symbolic equation for this reaction is:

It means that the correct answer is the first choice.

Yes, the molarity in both the cases will be different if the indicator is changed from methyl orange to phenolphthalein or from phenolphthalein to methyl orange.

Since molarity is defined as the Molar concentration, also known as molarity, amount concentration, or substance concentration, is a unit used to describe the amount of a substance in a solution expressed as a percentage of the volume of the solution or it is the number of moles of solute divided by volume of solution in liters.

So on changing indicator, the number of moles changes as the molar mass is changing, so the molarity and other observations will get changed too and may increase or decrease.

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Answer:

A. 53.3% N, 46.7% O

Explanation:

1st) It is necessary to add both quantities (10.48g of nitrogen and 11.96g of oxygen) to obtain the total mass of the sample, which represents 100%:

10.48g + 11.96g = 22.44g

22.44g represents the 100% of the sample.

2nd) Now we can calculate the percentage composition of the gas, using a mathematical rule of three and the amount of nitrogen and oxygen:

• Nitrogen:

• Oxygen:

We can also calculate the oxygen percentage by subtracting 100% minus the nitrogen percentage (46.7%):

100% - 4607% = 53.3%

So, the percentage composition is 53.3% N and 46.7% O.

In order to answer this question we will need a few steps

First one will be to set up the properly balanced equation:

2 Na + Cl2 -> 2 NaCl

20 grams of Na

10 grams of Cl2

From this balanced equation we see that the molar ratio between Na and Cl2 is 2:1, that means that for every 2 moles of Na, we will need 1 mol of Cl2 in order to proceed with the reaction

Now we need to identify the limiting and excess reactant, we will do that by checking how many moles of each element we have and how much we should have in order to properly react with the other element, let's check it:

Molar mass for Na is 23g/mol

23g = 1 mol

20g = x moles

x = 0.89 moles of Na in 20 grams

So if we have 0.89 moles of Na, we should have 0.44 moles of Cl2, but we don't know if we have this amount of moles of Cl2 in 10 grams of it, let's check

Molar mass for Cl2 is 71g/mol

71g = 1 mol

10g = x moles

x = 0.14 moles

We have fewer moles than we actually needed, let's do the same step but now focusing on Cl2

Cl2 in 10 grams has 0.14 moles, therefore we will have 0.28 moles of Na, remember the molar ratio 2:1

23g = 1 mol

x grams = 0.28 moles

x = 6.44 grams of Na

If we have 10 grams of Cl2, we would only need 6.44 grams of Na, since we have more available, we can say that Na is in excess and Cl2 is the limiting reactant

To find out the mass of NaCl produced from 10 grams of Cl2 (we have to use the limiting reactant), NaCl has a molar mass of 58.44g/mol and the molar ratio will be again 2:1, one mol of Cl2 and 2 moles of NaCl, if we have 0.14 moles of Cl2, therefore we will have 0.28 moles of NaCl

58.44 g = 1 mol

x grams = 0.28 moles

x = 16.4 grams, the value in the options is a little higher, but not too much higher, that must be due some rounding up

Letter A

In order to properly balance an equation, we need to make sure that the same amount of elements on the reactants side matches the number of elements on the products side, we can do that by increasing the number in front of each molecule, the so called stoichiometric coefficient. In the reaction from the question we can properly balance by adding the following stoichiometric coefficients

For our question, we have:

2 Ag2S -> 4 Ag + S2

The first step is to write the reaction using the molecular formulas of the substances:

Now that the equation is balanced, we have to divide the amount of each reactant by its stoichiometric coefficient, that in this case is 1 for both of them:

The least result will indicate the limiting reagent, which in this case is sulfuric acid. It means that its formula is H2SO4.

Basing our calculations in this reagent, we can find the maximum amount of calcium sulfate that is produced:

It means that the maximum amount of calcium sulfate that can be produced is 0.156 moles.

10L

The formula for calculating the molarity of a solution is expressed as:

Given the following parameters

• Moles of salt = 5 moles

• Molarity of solution = 0.5M

Substitute the given parameters into the formula

Hence the required volume of the solution is 10L

A chemical equation is known to be balanced if the total number of moles of elements at the reactant is equal to that of the product.

For the reaction between sodium chloride (NaCl) and potassium nitrate (KNO₃), the balanced reaction is given as;

You can see that the reactant ions exchange places to form new products (potassium chloride and sodium nitrate). This shows that the equation is a double displacement reaction

Explanations: Atoms are very small to be observed vissually, as a reslt we need the construction of a model to be able to successfully describe an atom.

Answer:

C. If the difference in electronegativity is from 0.6 to 1.7, the bond will be polar and covalent.

Explanation:

Let's see the type of bondings based on the electronegativity differences between atoms:

So based on this, the answer would be C. If the difference in electronegativity is from 0.6 to 1.7, the bond will be polar and covalent.

separate an oxidation-reduction equation into 2 half equations one for oxidation and one for reduction.

cu(s) ⇒ [tex]cu^{2+}[/tex](aq) + 2e-  ........ oxidation

[tex]mg^{2+}[/tex](aq) + 2e- ⇒ mg(s) ...........reduction

as with all chemical equations one must balance mass and charge both.

An oxidizing agent causes another  substance to be oxidized.The oxidizing agent is reduced.in other words to accept their electrons. Common oxidizing agents are oxygen, hydrogen peroxide and the halogens.

A reducing agent causes another substance to be reduced. the reducing agent is oxidised.for example hydrogen carbon hydrogen sulfide and Ammonia are reducing agents

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Answer

x = 2, y = 2

Explanation

The empirical formula is the simplest whole number ration that defines constituent atoms in a species.

The molecular formula is always a multiple of the empirical formula.

Since the empirical formula of the compound i given to be CH, ithen its molecula formula is:

From the periodic table, the molar masses of (H = 1.00784, C = 12.011)

Thus, the molecular formula is

(CH)n = (CH)₂ = C₂H₂

Therefore, CxHy = C₂H₂. The value of x and y is 2 and 2 respectively.

The value of x and y if its empirical formula is CH is x = 2, y = 2

38.95 g of Al is produced on reacting 100 g of Aluminium chloride with Calcium.

We need to write a balanced equation for the reaction. This is illustrated below:

2AlCl₃ + 3Ca —> 3CaCl₂ + 2Al

Molar Mass of AlCl₃

= 27 + (3x35.5)

= 27 + 106.5 = 133.5g/ mol

Mass of AlCl₃ from the balanced equation

= 2 x 133.5g

= 267g

Molar mass of Al= 26  

Mass of Al from balanced equation= 2×26

= 52

Molar Mass of CaCl₂ = 40 + (2 x 35.5)

= 40 + 71 = 111g/mol

Mass of CaCl₂ from the balanced equation

= 3 x 111 = 333g

From the equation,

133.5g of AlCl₃ produced 52g of Al

Therefore, 100g of AlCl₃ will produce

= (100 x 52)/133.5

= 38.95g of Al

So, 38.95 g of Al is produced on reacting 100 g of Aluminium chloride with calcium.

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ANSWER

There are 3.3 moles of Cl2 in 1.1 moles of SeCl6

EXPLANATION

Given that

The number of moles of SeCl6 is 1.1 moles

Firstly, write a balanced equation of the reaction

In the reaction above, 1 mole SeCl6 gives 3 moles Cl2

Let x be the number of moles of Cl2

Therefore, there are 3.3 moles of Cl2 in 1.1 moles of SeCl6

Molarity or molar concentration is a measure of the concentration of a chemical species, of a solute in a solution, using as units, number of moles, and volume in liters. The formula for Molarity is:

M = n/V

Where:

n = number of moles, 0.610 moles

V = volume in Liters, 0.707

Now we add these values into the formula:

M = 0.610/0.707

M = 0.863 M is the molarity

Percent compositions:

The volume of O₂ collected at 22 degrees Celsius and 728 mmHg would be produced by the decomposition of 8.15 grams of KClO₃ is 2.52 L

It is given that the mass of KClO₃ is 8.15g and the temperature is 22°C and the pressure is 728mmHg. The number of moles of KClO₃ is given by,

No of moles of KClO₃ = 8.15/122.55

No of moles of KClO₃ = 0.066 mol

The reaction for decomposition is,

2KClO₃ -----------> 2KCl + 3O2

2 mol of KClO3 gives 3 moles of O₂

Then, 0.66mol of KClO3 gives, 3/2(0.66) mol of O₂ which is 0.0998

The given temperature is 22 + 273 = 295K

The given pressure is 728mmHg which is 728/760 which is 0.958 atm

We know that

PV = nRT

0.958 x V = 0.0998x 0.0821x295

V = 2.52L

Therefore, the volume of Oxygen collected is 2.52L

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The OSHA limit for STEL-TWA is 2ppm and the PEL-STEL value is 4ppm to the exposure to nitric acid.

OSHA refers to Occupational Safety and Health Administration has adopted standard values for the exposure to harmful and hazardous chemicals so that the safety of workers and testing animals could be ensured.

Here, STEL-TWA stands for Short Term Exposure Limit - Time-Weighted average, and PEL-STEL stands for Permissible Exposure Limit- Short Term Exposure Limit.

This is usually set up in industries to ensure the safety of the workers and the maximum exposure short-term time limit is 15min and 2ppm for STEL-TWA and 4 ppm for PEL-STEL.

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The Law of Conservation of Mass can be state in different ways. Essentially, this law states that if we are on a closed system, no mass can be created nor dstroyed. In chemical terms, this means that in a chemical reaction the number of atoms of each element has to be the same in the reactants and the products.

Chlorine (Cl). Option C is correct

For an elements to be stable, it must attain its octet configuration that is the total number of electron in its outermost shell is must be 8 electrons.

For sulphur (atomic number of 16) with an electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^4. This shows that sulphur needs 2 electrons to complete its shell making the first option incorrect.

For hydrogen (atomic number of 1) will need one electron to attain duplet rule making the option B is incorrect.

For chlorine element (atomic number of 17), with electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^5. This shows that chlorine will need 1 more electron to make it stable

A 14.577 g sample of CaCl₂ was added to 12.226 g of K₂CO₃ and mixed in water. A 3.554 g yield of CaCO₃ was obtained then the percent yield of  CaCO₃ is  13.25%

Here given data is

14.577 g CaCl₂ was added to 12.226 g of K₂CO₃ and mixed in water

3.554 g yield of CaCO₃ was obtained

We have to calculate the percent yield of CaCO₃ = ?

Percent yield = actual yield/threotical yield×100

Actual yield = 3.554 g

Theroetical yield = 14.577 g CaCl₂ + 12.226 g of K₂CO₃

Theroetical yield = 26.803g

Now Percent yield = actual yield/threotical yield×100

Percent yield = 3.554 g /26.803g×100

Percent yield = 13.25%

The percent yield of  CaCO₃ is  13.25%

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The Croatian seismologist, Andrija Mohorovicic, discovered a boundary change in the Earth's layers  because he noticed that P-waves were refracted at the boundary.

Seismologists are described as Earth scientists, specialized in geophysics, who study the genesis and the propagation of seismic waves in geological materials.

Andrija Mohorovicic realized that as one crosses the boundary the predominant mineral composition of the rock changes, and the minerals on the mantle side enable seismic waves to travel faster.

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Answer:

a. N3-

b. Ca

c. As

d. Al

Explanation:

a. N or N3-

In this case, the largest species is N3- because it has 3 additional electrons in contrast to the neutral atom.

b. Ca or Ca2+

In this case, the largest species is Ca, because Ca2+ has 2 fewer electrons than the neutral atom of Ca.

c. Si or As

To analyze these elements, is is necessary to look for them in the Periodic Table of elements:

Since the atomic radius increases from top to bottom and from right to left, the largest is As.

d. Al or B

In this case, we also have to look for the elements in the Periodic table, and following the atomic radius increase, the largest is Al.

Answer

c. both

explanation

both structures have a triple bond on the second carbon and the have 6 carbons in the carbon chain

Calculations:

Balanced Reaction :

• 2 moles of Fe : 2 moles of iron (iii) oxide

• then 13.5 moles Fe : x

X = 13.5 *2 /2 = 13.5 moles of Fe

• This means that 13.5 mole of Fe2O3 will be produce.

No. of molecules = Moles * Avogardo Number

• This means that there are 8.1297 x10^24molecules of Fe2O3 from 13.5 moles Fe.

Answer: the combination "sugar and water" will form a solution.

Explanation:

The question requires us to determine which of the combinations given will form a solution.

To solve this question, let's consider this definition of solution: a homogenous mixture of two or more substances in relative amounts. This means that, to be considered a solution, two mixed substances must form a homogeneous mixture, i.e., without separation of phases.

Considering the options given by the question, we can say:

- oil and water do not mix (because they have different polarities), and separate in different phases when are put together;

- sand and water do not form a homogeneous mixture: sand is deposited at the bottom of the vessel and forms a separated phase of solid;

- sugar and water can form a homogeneous mixture, therefore they form a solution;

- sand and sugar form visible separated phases when mixed together (we can see the particles of sugar and sand separated).

Therefore, considering the points above, we can say that only sugar and water form a solution.

Answer:

3.73 g of Li.

Explanation:

What is given?

Volume of hydrogen gas, H2 (V) = 6.00 L.

Pressure (P) = 1.10 atm.

Temperature (T) = 25.0°C + 273 = 298 K.

R = 0.082 L*atm/mol*K.

Step-by-step solution:

First, we have to find the number of moles of hydrogen gas (H2) using the ideal gas formula:

where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant and T is the temperature on Kelvin scale. So let's solve for 'n' and replace the given values:

Based on this, we have 0.270 moles of H2.

You can see in the chemical equation that 2 moles of Li reacted produce 1 mol of H2, so we have to state a rule of three:

The calculation will look like this:

The final step is to convert 0.540 moles of Li to grams using its molar mass that can be found in the periodic table, which is 6.9 g/mol:

The answer is that we must use 3.73 g of Li to produce 6.00 L of H2 at 1.10 atm and 25.0 °C.