On the first chemistry test, 15 students got As , 20 students got Bs, and 19 students got Cs.

Part A
What is the percent of students who received Bs
Express your answer to the ones place.
Express your answer to two significant figures and include the appropriate units.

Part B
What is the percent of students who received Cs
Express your answer to the ones place.
Express your answer to two significant figures and include the appropriate units.

The balanced chemical equation for the reaction C + 2H2 → CH4 tells us that one mole of carbon produces one mole of methane. So, if 10.7 moles of methane are produced, then 10.7 moles of carbon are required to produce it.

To find the mass of carbon required to produce 10.7 moles of methane, we can use the molar mass of carbon (12 g/mol) and the following calculation:

Mass of carbon = Number of moles of carbon × Molar mass of carbon

Mass of carbon = 10.7 mol × 12 g/mol

Mass of carbon = 128.4 g

Therefore, 128.4 grams of carbon are required to produce 10.7 moles of methane, CH4.

Answer:

128.40g

Explanation:

Grams of carbon = moles of carbon * molar mass of carbon

Grams of carbon = 10.7 moles * 12 g/mol

Answer:

To convert a measurement of 0.050 ug/dL to g/mL, we need to multiply it by a conversion factor that relates micrograms (ug) to grams (g) and deciliters (dL) to milliliters (mL).

1 ug = 0.000001 g (or 1 g = 1,000,000 ug)

1 dL = 100 mL

So, the missing part of the equation would be:

(0.050 ug/dL) • (0.000001 g/ug) • (1 dL/100 mL) = 0.0000000005 g/mL

Therefore, the answer is 0.0000000005 g/mL.

Explanation:

In a combustion reaction, a substance reacts with oxygen to produce carbon dioxide and water. In this case, the hydrocarbon C10H8 (often known as naphthalene) is reacting with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O).

Therefore, the correct answer is: Combustion.

The options "synthesis" and "decomposition" do not apply to this particular reaction since synthesis involves the combination of simpler substances to form a more complex one, and decomposition involves the breakdown of a compound into simpler substances.

The maximum amount of product that can be obtained from given amounts of reactants in a chemical reaction. The correct answer is C.

A chemical reaction is a process that causes one group of chemical components to change chemically into another. Reactants are substances that interact to make new substances, whereas products are those substances that result from the interaction.

Chemical Reaction Types

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(i) A mole is the amount of a substance containing 6.022 × 10²³ particles.

(ii) Compounds are formed by the chemical bonding of different elements.

(iii) Molecular mass is the sum of atomic masses in a molecule.

(iv) There are two types of mix homogeneous and heterogeneous mixtures.

(v) Free radicals are highly reactive species with unpaired electrons.

(vi) Gram formula mass is the sum of atomic masses expressed in grams per mole.

(i) Mole: A mole is defined as the quantity of a substance that has an equal number of particles that are in 12 grams of carbon-12.

It is denoted by mol and is used in chemistry to measure quantities of atoms or molecules.

Example:1 mol of oxygen gas contains 6.022 × 10²³ oxygen molecules.

(ii) Compounds: Compounds are substances made up of two or more different elements that are chemically bonded together.

They can be broken down into simpler substances through chemical reactions.

Example:Water (H2O) is a compound made up of two hydrogen atoms and one oxygen atom that are chemically bonded together.

(iii) Molecular Mass: The molecular mass of a compound is the sum of the atomic masses of all the atoms in the molecule.

It is expressed in atomic mass units (amu) or grams per mole.

Example:The molecular mass of water (H2O) is 18.015 amu.

(iv) Types of Mixture: A mixture is a combination of two or more substances that are not chemically combined.

There are two types of mixtures - homogeneous and heterogeneous.

Example:A homogeneous mixture is a solution, such as saltwater, where the solute (salt) is evenly distributed in the solvent (water).

A heterogeneous mixture is a mixture that is not evenly distributed, such as oil and water.

(v) Free Radical: A free radical is an atom or molecule that has an unpaired electron in its outer shell and is highly reactive. They can be both harmful and helpful to the human body.

Example:A common free radical is the hydroxyl radical (OH·) that is formed by the body during metabolism.

(vi) Gram formula mass: The gram formula mass is the sum of the atomic masses of all the atoms in a compound.

It is expressed in grams per mole and is used to determine the mass of a certain number of molecules or atoms.

Example:The gram formula mass of water (H2O) is 18.015 g/mol.

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I really wish I could help but this is all I know

128.4 grams of carbon are required to produce 10.7 moles of methane.

The balanced chemical equation for the reaction C + 2H2 - CH4 is as follows:C + 2H2 ⟶ CH4.

In this equation, we can see that for one mole of methane (CH4), one mole of carbon (C) and two moles of hydrogen (H2) are required.

The molar mass of carbon is 12 g/mol.

The molar mass of methane is the sum of the molar masses of its constituent atoms, which is 12 g/mol (for carbon) + 4(1 g/mol) (for hydrogen) = 16 g/mol.

To find the amount of carbon required to produce 10.7 moles of methane, we can use the following proportion:1 mole CH4 : 1 mole C

Therefore,10.7 moles CH4 : x moles C.

Thus,x = 10.7 moles C.

Since we know the molar mass of carbon (12 g/mol), we can convert the moles of carbon to grams:mass = moles × molar massmass of carbon required = 10.7 moles × 12 g/mol= 128.4 g.

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- In reactions 1 and 2, the highlighted atom (oxygen) is reduced.

- In reaction 3, the highlighted atom (sulfur) is neither oxidized nor reduced.

- In reaction 4, the highlighted atom (oxygen) is reduced.

In the given chemical reactions, we need to identify whether the highlighted atom is being oxidized or reduced. Let's analyze each reaction individually:

Reaction 1: 4 HF (g) + SiO₂ (s) → SiF₄ (g) + 2 H₂O (g)

In this reaction, the highlighted atom is oxygen (O). Oxygen in SiO₂ undergoes a change in oxidation state from -2 to 0 in SiF₄. Therefore, the highlighted atom (oxygen) is reduced.

Reaction 2: 2 Cl (aq) + 2 H₂O (l) → 2 OH (aq) + H₂ (g) + Cl₂ (g)

In this reaction, the highlighted atom is oxygen (O). Oxygen in H₂O undergoes a change in oxidation state from -2 to -1 in OH. Therefore, the highlighted atom (oxygen) is reduced.

Reaction 3: H₂S (aq) + 2 NaOH (aq) → Na₂S (aq) + 2 H₂O (l)

In this reaction, the highlighted atom is sulfur (S). Sulfur in H₂S undergoes a change in oxidation state from -2 to -2 in Na₂S. Therefore, the highlighted atom (sulfur) is neither oxidized nor reduced.

Reaction 4: 2 H₂ (g) + O₂ (g) → 2 H₂O (g)

In this reaction, the highlighted atom is oxygen (O). Oxygen in O₂ undergoes a change in oxidation state from 0 to -2 in H₂O. Therefore, the highlighted atom (oxygen) is reduced.

To summarize:

- In reactions 1 and 2, the highlighted atom (oxygen) is reduced.

- In reaction 3, the highlighted atom (sulfur) is neither oxidized nor reduced.

- In reaction 4, the highlighted atom (oxygen) is reduced.

It's important to note that oxidation and reduction involve changes in the oxidation state of atoms, indicating the gain or loss of electrons. The analysis above is based on the change in oxidation state of the highlighted atom in each reaction.

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Answer:

See explanation

Explanation:

A mole is a counting unit, which means that it is like a dozen, or a pair, except that instead of having 12 or 2 of something, there are 6.022*10^23 of them. Why do chemists use moles instead of the number of atoms? That is where the boxes and apples come in. Lets say a company has 13340 apples, which is a lot. The company sends out and receives their apples in boxes of 667 apples. No one wants to say "we have thirteen thousand, three hundred and four hundred apples in stock right now." Instead, they all say "We just got twenty boxes of apples". You can see how the company doesn't like dealing with large numbers, so they use boxes to simplify apple counting. Chemists are the same. No one wants to say "Here, have six hundred two sextillion two hundred fourteen quintillion seventy-six quadrillion glucose molecules", instead, we/they say "Here, have a mole of glucose."

0.595 moles of water can be made at 112.6 grams of [tex]HNO_{3}[/tex] are consumed

To determine the number of moles of water produced when 112.6 grams of [tex]HNO_{3}[/tex] are consumed, we use the equation's stoichiometry and molar masses.

To determine the number of moles of water produced when 112.6 grams of [tex]HNO_{3}[/tex] are consumed, we need to use the molar mass of [tex]HNO_{3}[/tex] and the stoichiometric coefficients of the balanced chemical equation.

The molar mass of [tex]HNO_{3}[/tex] is calculated as follows:

1 mole of hydrogen (H) = 1 g/mol

1 mole of nitrogen (N) = 14 g/mol

3 moles of oxygen (O) = 3 × 16 g/mol = 48 g/mol

Adding these together, the molar mass of [tex]HNO_{3}[/tex] is 1 + 14 + 48 = 63 g/mol.

Now, we can set up a conversion factor using the stoichiometry of the balanced equation:

From the equation: 5 + 6 [tex]HNO_{3}[/tex] -> [tex]H_{2}SO_{4}[/tex] + 6 [tex]NO_{2}[/tex] + 2 [tex]H_{2}O[/tex]

From the coefficients: 6 moles of [tex]HNO_{3}[/tex] produce 2 moles of [tex]H_{2}O[/tex]

To find the moles of water produced, we use the following calculation:

112.6 g [tex]HNO_{3}[/tex] × (1 mol [tex]H_{2}O[/tex] / 63 g [tex]HNO_{3}[/tex]) × (2 mol [tex]H_{2}O[/tex] / 6 mol [tex]HNO_{3}[/tex]) = 0.595 mol [tex]H_{2}O[/tex]

Therefore, when 112.6 grams of [tex]HNO_{3}[/tex] are consumed, approximately 0.595 moles of water can be produced according to the given balanced equation and molar masses.

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The law that relates to the ideal gas law is P₁V₁/T₁ = P₂V₂/T₂.

This is known as Boyle's law, and it states that the pressure of a gas is inversely proportional to its volume at a constant temperature.

The other laws you mentioned are also gas laws, but they do not relate to the ideal gas law. Charles' law states that the volume of a gas is directly proportional to its temperature at a constant pressure. Avogadro's law states that the volume of a gas is directly proportional to the number of moles of gas at a constant pressure and temperature. Gay-Lussac's law states that the pressure of a gas is directly proportional to its temperature at a constant volume.

The ideal gas law is a combination of Boyle's law, Charles' law, Avogadro's law, and Gay-Lussac's law. It can be expressed as follows:

PV = nRT

where:

P = pressure of the gas (in Pa)

V = volume of the gas (in m³)

n = number of moles of gas

R = universal gas constant (8.314 J/mol K)

T = temperature of the gas (in K)

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Taking into account the reaction stoichiometry, 128.4 grams of C are required to produce 10.7 moles of methane.

In first place, the balanced reaction is:

C + 2 H₂ → CH₄

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

The molar mass of the compounds is:

Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

The following rule of three can be applied: If by reaction stoichiometry 1 mole of CH₄ is produced by 12 grams of C, 10.7 moles of CH₄ are produced by how much mass of C?

mass of C= (10.7 moles of CH₄×12 grams of C)÷1 mole of CH₄

mass of C= 128.4 grams

Finally, 128.4 grams of C are required.

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The researcher initially added approximately 13 g of KF to the water.

First, you calculate the amount of heat absorbed by the water when the KF dissolves.

We can use the equation:

q = mCΔT

We can assume that the KF has a negligible heat capacity and does not contribute to the heat absorption.

Using the given values, we have:

q = mCΔT

q = (238 g - mKf)(4.184 J/g·°C)(31.51°C - 18.98°C)

q = (238 g - mKf)(86.05 J/g)

Next, we can use the fact that the amount of KF added is equal to the amount of KF dissolved in the water.

We can also assume that the KF fully dissociates into K+ and F- ions when it dissolves:

KF(s) → K+(aq) + F-(aq)

Therefore, the moles of K+ ions are equal to the moles of KF added to the water.

We can use the following equation to calculate the moles of K+ ions:

moles K+ = mass KF / molar mass KF

where the molar mass of KF is 58.10 g/mol.

Since the solution is electrically neutral, the moles of F- ions are also equal to the moles of KF added.

Next, we can use the following equation to calculate the concentration of the ions in the solution:

C = moles / volume

Assuming that the volume of the solution is equal to the mass of the solution (since the density of water is close to 1 g/mL), we have:

C K+ = moles K+ / (238 g - mKf)

C F- = moles F- / (238 g - mKf)

Finally, we can use the fact that KF is a strong electrolyte and dissociates completely in water to write the following equation for the heat absorbed during the dissolution:

q = (moles K+) ΔHfus + (moles K+)ΔHsol + (moles F-)ΔHsol

The heat of fusion of KF is 10.8 kJ/mol, and the heat of solution is -155.2 kJ/mol.

Substituting all the equations and values above, we get:

(238 g - mKf)(4.184 J/g·°C)(31.51°C - 18.98°C) =

((mKf / 58.10 g/mol) ΔHfus + (mKf / 58.10 g/mol)ΔHsol + (mKf / 58.10 g/mol)ΔHsol) + ((238 g - mKf) (mKf / 58.10 g/mol) (-155.2 kJ/mol))

Simplifying this equation gives:

mKf ≈ 13 g

Therefore, the researcher initially added approximately 13 g of KF to the water.

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