I just need # 6,8 and 12 pls

The positive value of 571.6 kJwhich is the enthalpy change tells us that it is exothermic

When energy is released into the surrounding area during a chemical reaction, it's considered an exothermic reaction with ΔH < 0. Conversely, endothermic reactions result from heat absorption with ΔH > 0.

The provided equation's positive value of 571.6 kJ reveals that heat is pouring out of the reaction, causing negative changes in enthalpy and firmly placing this chemical event as exothermic in nature.

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Answer:

2.00 L of a gas is collected at 25.0°C and 745.0 mmHg

Explanation:

Answer:

In chemistry, a compound is a substance made up of two or more different chemical elements combined in a fixed ratio. When the elements come together, they react with each other and form chemical bonds that are difficult to break.

Explanation:

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The temperature of the gas can be gotten from the ideal gas equation as 229.7°C.

PV = nRT

where:

P is the pressure of the gas in units of pascals (Pa)

V is the volume of the gas in units of cubic meters (m³)

n is the amount of substance of the gas in units of moles (mol)

R is the ideal gas constant with a value of 8.314 J/(mol·K)

T is the absolute temperature of the gas in units of kelvins (K)

We know that;

PV = nRT

Then;

T = PV/nR

T = ?

P = 125.6 kPa or 1.24 atm

n = 0.453 moles

R = 0.082 atmL/K-1mol-1

Then;

T = 1.24  * 15/0.082 * 0.453

= 18.6/0.037

= 502.7 K or 229.7°C

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The planets, moons, and smaller objects in the solar system have several characteristics are; Size, Composition, Orbits, Atmosphere, and Evolution.

Planets are generally much larger than moons and smaller objects in the solar system. For example, the largest planet in our solar system, Jupiter, has a diameter of about 143,000 kilometers, while the Moon, Earth's natural satellite, has a diameter of about 3,474 kilometers.

Planets are typically made up of a combination of rock and/or gas, while moons and smaller objects can have a variety of compositions. Moons can be rocky, icy, or a mix of both, while smaller objects such as asteroids and comets can also have diverse compositions including rock, metal, ice, and other materials.

Planets and moons have different orbits around the Sun or their respective planets. Planets orbit the Sun in nearly elliptical paths, while moons orbit their parent planet in elliptical or nearly circular orbits.

Planets and some moons can have substantial atmospheres, while smaller objects in the solar system may have little to no atmosphere. For example, Earth has a dense atmosphere composed mainly of nitrogen, oxygen, and trace gases, while the Moon has no significant atmosphere.

Planets, moons, and smaller objects in the solar system have different origins and evolutionary histories. Planets are thought to have formed from the solar nebula, a cloud of gas and dust left over from the formation of the Sun. Moons can form throuugh various mechanisms, such as accretion, capture, or giant impacts. Smaller objects, such as asteroids and comets, are remnants from the early solar system and can provide valuable information about its history and evolution.

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The moles of NaOH used is 0.0008 moles

The molarity of the acid  is 0.008 M

The molarity of the acid is found as follows:

Moles of NaOH used = concentration of NaOH × volume of NaOH used

the average volume of NaOH used = 8.0 mL

moles of NaOH = 0.1 M × 8.0 mL

moles of NaOH = 0.0008 moles

Molarity of acid:

Assuming the acid is monobasic, the mole ratio of acid to base is 1 : 1

The volume of acid used is 100 mL

The molarity of acid = moles of acid / volume of acid in liters

The molarity of acid = 0.0008 moles / 0.1 L

The molarity of acid  = 0.008 M

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(a). Sodium hydroxide: NaOH, aluminum hydroxide: [tex]Al(OH)_3[/tex]

(b). The parentheses are necessary for aluminum hydroxide because the hydroxide polyatomic ion has a subscript of 3, indicating that there are three hydroxide ions for every one aluminum ion.

a) The formula for sodium hydroxide is NaOH, and the formula for aluminum hydroxide is [tex]Al(OH)_3[/tex]

b) Aluminum hydroxide requires brackets because there are three hydroxide ions for every one aluminum ion, according to the hydroxide polyatomic ion's subscript of 3. Without the parentheses, it would be unclear whether the subscript of 3 applies to only the oxygen or to the entire hydroxide ion. By enclosing the entire hydroxide ion in parentheses and placing the subscript outside the parentheses.

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The value of K is given as 2344 thus more products are obtained at equilibrium since the equilibrium constant is very large.

The equilibrium constant ( K ) is equal to the rate constant for the forward reaction divided by the rate constant for the reverse reaction.

The balanced equation is -

CaO(s) + CH₄(g) + 2H₂O(g) —> CaCO₃(s) + 4H₂(g)

K = [CaCO₃] [H₂]⁴ / [CaO] [CH₄] [H₂O]²

Since the value of K = 2344, which is large, more of products will be formed in the reaction.

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Kb for trimethylamine is 1.0 × 10^-2.5.

We can use the relationship between Kb and Ka for a conjugate acid-base pair:

Kb × Ka = Kw

The pKa is related to the pH :

pKa + pKb = 14.00

pKb = 14.00 - pKa

We can calculate the pKa using the relationship:

pH = pKa + log([base]/[acid])

Therefore, [base] = [acid], and we can simplify equation to:

pH = pKa + log(1)

Therefore, the pKa of trimethylammonium ion is 11.5.

Now :

Kb × Ka = Kw

Kb = Kw ÷ Ka

Since we know that Kw = [tex]1.0 * 10^{-14[/tex]and Ka =[tex]10^{-11.5[/tex] (from the pKa value we calculated earlier), we can substitute these values to get:

[tex]Kb = (1.0 * 10^{-14}) / (10^{-11.5}) = 1.0 * 10^{-2.5[/tex]

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The kinetic energy of the particles of a substance affected during a phase change is Kinetic energy does not change, but the potential energy does.

A phase change  can be described as the physical process  whereby the substance can be transformed from one phase to another.

It should be noted that the change do take place in a case whereby  you are adding  as well as removing heat  which can be considered as  melting point or the boiling point of the substance and this can be understood using phase change.

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The heat capacity of a substance or system is defined as the amount of heat required to raise the temperature through 1°C. It is an extensive property and its value depends on the quantity of matter present.

The heat needed to raise the temperature of 1 gram of the substance through 1°C is the specific heat capacity.

Heat required is:

q = mc (T₂ - T₁)

m = V × ρ

q = (130 + 130) × 1.0 × 4.18 ( 30.5 - 21.8) = 9455.16 J

9455.16 J = 9.45516 kJ

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Answer:

Chemical reactions in living things are the chemical processes that occur within living organisms to maintain their biological functions. These reactions are essential for metabolism, growth, reproduction, and response to stimuli. They involve the conversion of one or more substances into new substances with different physical and chemical properties.

Some examples of chemical reactions in living things include:

Cellular respiration: the process by which cells convert nutrients into energy in the form of ATP. This process involves the oxidation of glucose to produce carbon dioxide, water, and ATP.

Photosynthesis: the process by which plants and other organisms convert light energy into chemical energy in the form of glucose. This process involves the conversion of carbon dioxide and water into glucose and oxygen.

Digestion: the process by which food is broken down into simpler substances that can be absorbed and used by the body. This process involves the hydrolysis of complex carbohydrates, proteins, and lipids into simpler molecules such as glucose, amino acids, and fatty acids.

DNA replication: the process by which cells make copies of their DNA before cell division. This process involves the synthesis of new strands of DNA from existing strands.

Chemical reactions in living things are regulated by enzymes, which are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes are specific to particular substrates and are critical for the proper functioning of metabolic pathways. Any disruption in these chemical reactions can lead to metabolic disorders and diseases.

Explanation:

To generate 6106 kJ of heat, 9.5 moles of CH₃OH are required.

The given reaction releases -1280 kJ of heat. We need to find how many moles of CH₃OH are required to release 6106 kJ of heat.

From the given balanced equation, we know that 2 moles of CH₃OH releases 1280 kJ of heat.

Therefore, 1 mole of CH₃OH will release 1280 kJ / 2 = 640 kJ of heat.

To release 6106 kJ of heat, we can use the following proportion:

2 moles CH₃OH / 1280 kJ = x moles CH₃OH / 6106 kJ

Solving for x, we get:

x = (2 moles CH₃OH x 6106 kJ) / 1280 kJ = 9.5 moles CH₃OH

Therefore, 9.5 moles of CH₃OH are required to release 6106 kJ of heat.

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Answer:

Fluorobenzene

Explanation: Fluorobenzene is an organic compound, which is a derivative of benzene. It has a fluorine atom attached to one of the carbon atoms in the benzene ring. It appears as a colorless liquid and has a slightly sweet odor. Fluorobenzene is used as a solvent and catalyst in various chemical reactions. It is also used in the production of agrochemicals and pharmaceuticals. Due to its high solubility in water, it can contaminate groundwater and pose a risk to human health and the environment.

Exoplanets are usually gigantic, fireballs that are close to the sun. Therefore, the correct option is option B.

Any planet outside of our solar system is an exoplanet. The majority of exoplanets orbit other stars, while rogue planets—free-floating exoplanets that are unattached to any star—orbit the galactic centre.

The majority of the exoplanets found so far are in the Milky Way, which is a rather tiny area of our galaxy. The Kepler Space Telescope of NASA has revealed that the galaxy has more planets than stars. Exoplanets are usually gigantic, fireballs that are close to the sun.

Therefore, the correct option is option B.

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The mass percentage is an important method which is used to calculate the concentration of a solution. The amount of water needed to add in order to make 17.85 % NaCl solution is 230.1 g.

The mass percentage of a component in a solution is defined as the mass in grams of that component present per 100 g of the solution. The term mass percentage is denoted as w/w. It is used to calculate the concentration of a binary solution.

Mass percentage = Mass of the component in the solution / Total mass of solution × 100

17.85 = 50.0 / 50.0 + x × 100

0.1785 (50.0 + x) = 50.0

8.925 + 0.1785 x = 50.0

0.1785 x = 41.075

x = 230.1 g

Thus the amount of water added to make the solution is 230.1 g.

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The molar mass of 2.62 mol of iron(III) sulfate is 1050.8 g.

Thus, the molar mass of iron(III) sulfate can be calculated by summing the atomic masses of its constituent atoms. The molar mass of a compound is the sum of the atomic masses of all the atoms present in a chemical formula of the compound which is then multiplied by the number of atoms of each element in the formula.

In iron(III) sulfate, the atomic mass of iron will be 111.70 g/mol. The atomic masses of Sulphur and oxygen will be 96.18 g/mol and 192.0 g/mol, respectively. Adding atomic masses of its constituent atoms will be 400.88 g/mol. Therefore, the molar mass of 2.62 mol of iron(III) sulfate is 1050.8 g.

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The why there are so many carbon-based compounds is that B. Carbon can form up to six bonds with other carbon atoms and atoms of other elements.

Carbon  can be described as the element that posses 4 electrons in its outermost shell,  and it has the asbility to gain or loss 4 electrons to so it can have  nobel gas configuration.

It should be noted that Catenation is one of the  unique ability of carbon  which help it to form bonds with other atoms of carbon  and due to this reason, it have the ability to record a long chains of different types of compounds.

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It is the primary source which helps the students to relate in a personal way to events of the past and promote a deeper understanding of history as a series of human events. The primary source is better, because it contains more charts. The correct option is B.

The sources which are closest to the origin of the information and contain raw information which must be interpreted by the researches are called the primary sources. The secondary sources are closely related to the primary sources and often interpret them.

A direct access to the subject of our research is given by the primary source whereas the secondary source provides only second hand information and comments of other researches.

Thus the correct option is B.

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The magnitude of the net force on the crate is 13 N.

Generally, in science, the word 'force' has a very precise meaning. Force is usually described as a push or a pull.

Generally the magnitude of the force is described as the number which is used to represent the strength of the force. Let's consider an example, suppose the force is equal to 10 N towards the east direction and 'towards east' indicates direction while '10' indicates the magnitude of the force. So we can say that basically, Magnitude is the 'value' or 'amount' of any physical quantity.

Here, assuming that the two forces are acting opposite,

Net force = 53 N - 40 N = 13 N

The given question is incomplete and the complete question is given in the image attached below.

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The rate constant that we have at 381 K will be 2.19 M/s.

The Arrhenius equation suggests that the rate of a reaction increases with temperature, because higher temperatures provide more kinetic energy to the reactant molecules, making them more likely to react.

By the use of the Arrhenius equation, we have that;

ln k2/k1 = -Ea/R(1/T2 - 1/T1)

ln k2/0.178 = -37.8 * 10^3/8.314 (1/381 - 1/280)

ln k2/0.178 = - 4647 * (2.62 - 3.57) * 10^-3

lnK2 = 0.786

k2 =e^0.786

k2 = 2.19 M/s

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The molar concentration of NH₃ is 0.17 M.

The equilibrium constant expression for the given reaction is:

We are given Kc = 1.7 × 10² and the molar concentrations of H₂ and N₂ in the equilibrium mixture as 0.21 M and 0.015 M, respectively. Let x be the molar concentration of NH₃ at equilibrium. Then, we can write:

x = 0.017 M or 0.17 M (since there are two NH₃ molecules produced for every three H₂ molecules consumed, we take the square root of the calculated value to get the molar concentration of NH₃)

Therefore, the molar concentration of NH₃ in the equilibrium mixture is 0.17 M.

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Answer & Explanation:

Scientists can use radiometric dating to reconstruct the geologic history of the area and support or reject their hypothesis of a disappearing and reappearing lake by analyzing the sediments and other geological features present in the area. Radiometric dating, such as carbon-14 dating, can determine the age of the sediments, fossilized remains, and other materials. By analyzing the age and composition of these materials, scientists can track changes in the environment over time, including periods of drought or increased precipitation that could cause a lake to dry up or reform.

To ensure the accuracy of their radiometric dating, scientists can use calibration methods, such as cross-dating with other dating techniques like dendrochronology (tree-ring dating), or comparing their results with well-dated samples from similar or nearby environments. This can help validate the radiometric dating results and provide more confidence in the reconstructed geologic history and any conclusions drawn from it regarding the presence or absence of a lake in the area at different times.

The correct electron configuration for an atom of Magnesium (Mg) is 2, 7.

The distribution of electrons among an atom's or ion's energy levels and sublevels is referred to as electron configuration. It outlines how electrons are grouped in numerous shells and subshells surrounding an atom's nucleus.

The electron configuration is frequently expressed in shell and subshell notation, such as 1s², 2s², 2p⁶, 3s², 3p², where the numbers represent the energy level or shell and the letters s, p, d, and f represent the sublevels or orbitals inside each shell.

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The molar solubility of CuS is 7.8 x 10⁻¹⁹ M.

The solubility product expression for CuS is:

Since CuS dissociates to form one Cu²⁺ ion and one S²⁻ ion, the molar solubility of CuS can be represented as x. Therefore, at equilibrium:

Substituting these values in the Ksp expression:

Solving for x, we get:

Therefore, the molar solubility of CuS is 7.8 x 10⁻¹⁹ M.

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The complete question is:

Calculate the molar solubility, S , of CuS if it has a Ksp value of 6×10⁻³⁷.

Answer:

The correct answer is B

Explanation:

The rate constant and reaction are both increased

105.0 mL of alcohol is dissolved in water and the solution is diluted to a total final volume of 250 mL the final concentration of ethanol in the solution is 0.00722 M.

To calculate the final concentration of ethanol in the solution, we need to know the amount of ethanol present in the solution before and after dilution. We can use the following formula to calculate the final concentration:

Cfinal = Cinitial x (Vinitial / Vfinal)

where Cinitial is the initial concentration of ethanol, Vinitial is the initial volume of the solution, Vfinal is the final volume of the solution, and Cfinal is the final concentration of ethanol.

First, let's find the initial concentration of ethanol in the solution. We know that 105.0 mL of alcohol is dissolved in water, but we don't know the concentration of the alcohol.

Let's assume that the alcohol is pure ethanol (which is not always the case in reality), which has a density of 0.789 g/mL at room temperature. Therefore, the mass of ethanol in 105.0 mL of alcohol is:

mass of ethanol = volume of alcohol x density of ethanol

= 105.0 mL x 0.789 g/mL

= 82.845 g

The molar mass of ethanol is 46.07 g/mol, so the number of moles of ethanol in 82.845 g of ethanol is:

moles of ethanol = mass of ethanol / molar mass of ethanol

= 82.845 g / 46.07 g/mol

= 1.797 mol

The initial volume of the solution is 105.0 mL, so the initial concentration of ethanol is:

Cinitial = moles of ethanol / initial volume of solution

= 1.797 mol / 105.0 mL

= 0.0171 M

Now, let's calculate the final concentration of ethanol. We know that the final volume of the solution is 250 mL. Using the formula above, we get:

Cfinal = Cinitial x (Vinitial / Vfinal)

= 0.0171 M x (105.0 mL / 250 mL)

= 0.00722 M

Therefore, the final concentration of ethanol in the solution is 0.00722 M.

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Around 450 nm is the wavelength of the spectral line for potassium chloride. The distance among identical spots between two succeeding waves is known as the wavelength.

The distance among identical spots between two succeeding waves is known as the wavelength, which is a feature of waves. The wavelength of a wave is the distance across one wave's peak (or trough) and the next. In mathematics, the Greek symbol lambda () is used to denote wavelength. The colour of light is determined by its wavelength, and the pitch of sound is determined by its wavelength. Around 450 nm is the wavelength of the spectral line for potassium chloride.

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