A sample of pure water has a hydronium concentration of 1.0 × 10-7 M. What is the pH of the water?

Final answer:

Diluting 80.00 mL of 9.13×10⁻² M NaOH to a concentration of 1.60×10⁻² M would result in 456.25 mL of the solution, calculated using the dilution formula M1V1 = M2V2.

Explanation:

The question asks about diluting a solution of NaOH from an initial concentration to a lower concentration while preserving the number of moles of solute. This is a classic chemistry problem involving the concept of molarity and dilution. The formula used to solve such problems is M1V1 = M2V2, where M1 and V1 are the molarity and volume of the initial solution, respectively, and M2 and V2 are the molarity and volume of the final solution, respectively.

Given: M1 = 9.13×10⁻² M, V1 = 80.00 mL, M2 = 1.60×10⁻² M. We need to find V2.

Using the formula:

Therefore, diluting 80.00 mL of 9.13×10⁻² M NaOH to a concentration of 1.60×10⁻² M would result in a volume of 456.25 mL of the solution.

The face-centered cubic unit cell of nickel has an edge length of 352.4 pm. The density of nickel is 8.9 gcm⁻³.

The mass of a material per unit of volume is its density. Density is most frequently represented by the symbol, however the Latin letter D may also be used. Density is calculated mathematically by dividing mass by volume.

Because it enables us to predict which compounds will float and which will sink in a liquid, density is a crucial notion. As long as an object's density is lower than the liquid's density, it will often float.

Four atoms altogether make up a face-centered cubic unit cell. As a result, a face-centered cubic unit cell has a density of 4 x M / A3 x Na. There are two types of density, absolute and relative density.

Thus, The density of nickel is 8.9 gcm⁻³.

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Final answer:

Nickel does not crystallize in a simple cubic structure because the calculated density for a simple cubic arrangement is much lower than the actual density of nickel. The actual density of nickel (8.90 g/cm³) indicates that nickel has a denser crystal structure, specifically a face-centered cubic lattice, which contains more atoms per unit cell.

Explanation:

No, nickel does not crystallize in a simple cubic structure. If nickel were to crystallize in a simple cubic structure, we would calculate its density based on the volume occupied by one atom in the unit cell. To find the volume of the unit cell, we would cube the edge length of the unit cell, which is given as 0.3524 nm (convert to cm: 3.524 x 10−8 cm). The volume of the unit cell would then be (3.524 x 10−9 cm)3 = 4.376 x 10−23 cm3.

Knowing that there is one atom per unit cell in a simple cubic structure and using the molar mass of nickel (58.6934 g/mol) along with Avogadro's number (6.022 x 1023 atoms/mol), we can determine the mass of one atom of nickel. The mass of one mole of nickel atoms divided by Avogadro's number gives the mass of a single atom to be 9.746 x 10−23 g. Therefore, the density of nickel in a simple cubic structure would be the mass of one atom divided by the volume of the unit cell, equating to 2.23 g/cm3.

However, the actual density of Ni is 8.90 g/cm3, which is significantly higher than what we would expect for a simple cubic structure. This implies that nickel crystallizes in a denser structure, such as a face-centered cubic (fcc) lattice, where more atoms are present per unit cell compared to a simple cubic structure. In an fcc lattice, there are effectively 4 atoms per unit cell.

A gallon of water with a mass of 3.79 kg is equal to 208.76 mol of water.

To find out how many moles of water (H2O) are in a gallon, we need to use the molar mass of water as a conversion factor.

The molar mass of water is 18.02 g/mol. To convert the mass of water from kg to g, we can multiply the number of kg by 1000.

Therefore, a gallon of water with a mass of 3.79 kg is equal to 208.76 mol of water.

Mg^2+ + EDTA^4-   ->   MgETDA^2-

number µmoles of EDTA used = 21.3 µl x 1 x 10^-2 M = 21.3 µl x 1 x 10^-2 µm/µl = 21.3 x 10^-2 = 0.213 µmoles EDTA

µmoles Mg^+2 present = 0.213 µmoles because the stoichiometry ratio of the above equation is 1:1

[Mg^+2] = 0.213 µmol / 25 µl = 0.00852 µmol/µl = 0.00852 M = 8.52 x 10^-3 M

The answer is 8.52 x 10^-3 M

Answer:

Extrusive igneous rock

Explanation:

The igneous rocks that are crystallized on the earth's surface are commonly known as the extrusive igneous rock. These rocks are characterized by the presence of fine-grained crystals which is due to the rapid cooling of the magma, as it does not get enough time for the crystals to form. These are also sometimes comprised of volcanic glasses.which are formed on the surface due to the eruption of volcanoes.

When the hot intruding magma crystallizes below the earth's surface, then it is called intrusive igneous rocks. For example, granite, diorite and gabbro.

On the other hand, when the hot uprising magma crystallizes on or near the earth's surface, then it is known as extrusive igneous rocks. For example, basalt, rhyolite and andesite.

Final answer:

Buffers maintain a steady pH in a solution but not necessarily a neutral pH of 7. They can maintain acidic, neutral, or basic pH levels depending on their composition and are essential for processes requiring stable pH conditions, such as in human blood.

Explanation:

The question about whether a buffer is supposed to keep the pH of a solution at 7 (neutral) reflects a common misconception. Buffers do not necessarily maintain a pH of 7. They are solutions that consist of a weak acid and its conjugate base and function to moderate pH changes when an acid or base is added. This helps maintain a steady pH, but the specific pH maintained by a buffer depends on the properties of the acid-base pair it is made from. For example, the pH of a buffer can be acidic, neutral, or basic, depending on its composition. The crucial function of a buffer is its capacity to absorb excess H⁺ ions or OH⁻ ions, thus preventing significant shifts in pH.

It's important to understand that the pH scale ranges from 0 to 14, with 7 being neutral. Solutions with a pH lower than 7 are considered acidic, and those with a pH higher than 7 are basic. Buffers can be designed to maintain any pH within this range, depending on the needs of the environment or process they are used in. For instance, human blood has a buffer system that maintains its pH around 7.35 to 7.45, slightly alkaline, which is crucial for physiological functions.

Final answer:

The balanced chemical equation for the reaction between NaOH and HCl is NaOH (aq) + HCl (aq) → NaCl (aq) + H₂O (l). It is a neutralization reaction with a one-to-one molar ratio.

Explanation:

The balanced chemical equation to show the reaction of NaOH with the monoprotic acid HCl is as follows:

NaOH (aq) + HCl (aq) → NaCl (aq) + H₂O (l)

This reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl) is a typical acid-base reaction where NaOH is the base and HCl is the acid. When NaOH and HCl react together, they form sodium chloride (NaCl) and water (H₂O). This reaction is also called a neutralization reaction and in this case, occurs in a one-to-one molar ratio where one mole of NaOH reacts with one mole of HCl to produce one mole of NaCl and one mole of water.

The answer is 4 valence electrons

The percentage of morphine in the white powder at the crime scene is 81%.

The goal here is to find the percentage of morphine in the white powder. To do this, we first need to know the amount of morphine in moles. Since morphine is a weak base similar to ammonia, it reacts with HCl (hydrochloric acid), with one mole of morphine reacting with one mole of HCl.

The molar concentration of HCl (0.0100 M) multiplied by its volume (2.84 ml or 0.00284 L) will give us the number of moles of HCl used, which also equals the number of moles of morphine in the mixture. Therefore, number of moles of morphine = 0.0100 M x 0.00284 L = 0.0000284 moles.

Morphine's molecular weight is 285.34 g/mol, so the weight of morphine in the mixture = moles x molecular weight = 0.0000284 moles x 285.34 g/mol = 0.0081 grams or 8.1 mg. As the initial weight of the powder was 10.00 mg, the percentage of morphine in the sample is (8.1/10.00)*100 = 81%. Therefore, 81% of the mysterious white powder is morphine.

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The electrostatic potential energy between an electron and a proton can be calculated using the equation PE = k(q1q2)/r, where k is the Coulomb constant, q1 and q2 are the charges of the electron and proton respectively, and r is the separation between them. Plugging in the given values, the electrostatic potential energy can be calculated.

The electrostatic potential energy between an electron and a proton can be calculated using the equation PE = k(q1q2)/r, where k is the Coulomb constant, q1 and q2 are the charges of the electron and proton respectively, and r is the separation between them.

In this case, the charge of an electron is -1.6 x 10-19 C and the charge of a proton is +1.6 x 10-19 C. The separation between them is 54 pm, which is equal to 54 x 10-12 m.

Plugging in these values, we get:
PE = (9 x 109 N m2/C2)((-1.6 x 10-19 C)(1.6 x 10-19 C))/(54 x 10-12 m)

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The electrostatic potential energy (in joules) between an electron and a proton that are separated by 54 pm is approximately [tex]- 4.25 \times 10^{-18} J[/tex].

To calculate the electrostatic potential energy between an electron and a proton that are separated by a distance of 54 picometers (pm), we can use the formula for the electrostatic potential energy [tex]E_{pot}[/tex]​ of two point charges:

[tex]E_{pot} = - \frac{k_e \cdot q_1 \cdot q_2}{r}[/tex]

Where:

1. Convert 54 pm to meters: 54pm = 54 × 10⁻¹² m

2. Substituting values into the equation: Since the charges of the proton and electron are equal and opposite, we have:

Therefore, substituting these values:

3. Calculating the potential energy:

The negative sign indicates that the potential energy is attractive, which is characteristic of opposite charges (the electron and proton).

The reaction SO3 (g) + H2O (l) → H2SO4 (aq) is classified as an acid-base reaction, specifically demonstrating the behavior of sulfur trioxide (an acid) reacting with water (a base) to produce sulfuric acid. Also, this reaction can be considered a type of synthesis reaction.

The equation provided, SO3 (g) + H2O (l) → H2SO4 (aq), is an example of an acid-base or a synthesis reaction. In acid-base reactions, an acid (SO3 in this case) combines with a base (H2O here) to form water and an ionic compound (H2SO4 here, a strong acid). In a more general sense, this is also a synthesis reaction because two or more simple substances (SO3 and H2O) combine to create a more complex one (H2SO4).

Moreover, taking into consideration the

acid-base behavior

of substances and their reactions, an acid would donate a proton and a base would accept it, thus, in our reaction, H2O acts as a base accepting a proton from SO3.

Additionally, the process of synthesizing sulfuric acid from sulfur dioxide and water is an important industrial method in the production of this widely used chemical.

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The reaction [tex]SO_3 (g) + H_2O (l) \rightarrow H_2SO_4(aq)[/tex] is classified as a synthesis reaction. It involves the combination of sulfur trioxide and water to form sulfuric acid. Sulfuric acid in water acts as a dibasic acid, forming bisulfate and sulfate anions.

The classification for the reaction [tex]SO_3 (g) + H_2O (l) \rightarrow H_2SO_4(aq)[/tex] is a synthesis reaction. This type of reaction occurs when two or more simple substances (in this case, sulfur trioxide and water) combine to form a more complex substance (sulfuric acid). Sulfuric acid is a strong protic acid and in water, it acts as a dibasic acid, forming bisulfate ([tex]HSO_4^-[/tex]) and sulfate ([tex]SO_4^{2-[/tex]) anions.

First Ionization:

[tex]H_2SO_4 (aq) + H_2O (l) \rightarrow H_3O^+ (aq) + HSO_4^- (aq)[/tex]

Second Ionization:

[tex]HSO_4^- (aq) + H_2O (l) \rightarrow H_3O^+ (aq) + SO_4^{2- (aq)[/tex]

In conclusion, the reaction of [tex]SO_3[/tex] with [tex]H_2O[/tex] forming [tex]H_2SO_4[/tex] is a classic example of a synthesis reaction in chemistry.

The reaction between 67.0 g of silicon dioxide (SiO2) and hydrofluoric acid (HF) will produce roughly 40.16 g of water (H2O).

The question is related to a chemical reaction between silicon dioxide (SiO2) and hydrofluoric acid (HF) which produces silicon tetrafluoride (SiF4) and water (H2O). From the balanced equation, we can see that for each mole of SiO2 reacted, 2 moles of H2O are produced. To find out the mass of water produced from 67.0 g of SiO2, we first need to determine the number of moles of SiO2 in 67.0 g. Using the molar mass of SiO2 (60.08 g/mol), we find that 67.0 g corresponds to 1.115 moles. As the reaction produces 2 moles of water for each mole of SiO2, this means we have 2 * 1.115 = 2.23 moles of water. The molar mass of water is 18.015 g/mol, so this equates to approximately 40.16 g of water.

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Answer:

F⃗ mag  =

−cosθj^ + sinθi^

Explanation:

use cross product

Final answer:

The magnetic force acting on a positive charge moving in the xy plane with a velocity vector can be determined using the right-hand rule and the cross-product formula.

Explanation:

The direction of the magnetic force acting on a positive charge moving in the xy plane with velocity v⃗ =vcos(θ)i^+vsin(θ)j^, when the local magnetic field is in the +z direction, can be determined using the right-hand rule. First, join the tails of the velocity vector and the magnetic field vector. Then, curl your right fingers from the velocity vector to the magnetic field vector. The direction in which your right thumb points is the direction of the force. In this case, the magnetic force would be directed into the page.

If the velocity and magnetic field are parallel to each other, there is no orientation of the hand that will result in a force direction. Therefore, the force on the charge is zero.

If the velocity vector is given as v = (2.0î – 3.0ĵ + 1.0k) × 10^2 m/s, the force can be calculated using the cross-product formula.

The number of moles of hydrogen gas in 345 mL volume at 752 torr and 29 ∘C, after accounting for the vapor pressure of water, is calculated using the Ideal Gas law equation and is approximately 0.014 moles.

To determine the number of moles of hydrogen gas in a given volume, we use the Ideal Gas Law (PV = nRT). Here, P is pressure (752 torr), V is the volume (345 mL, which is 0.345 L), T is the absolute temperature (29 + 273 = 302 K) and R is the gas constant (0.08206 L⋅atm/(mol⋅K)).

Convert the pressure from torr to atm, 752 torr is roughly equivalent to 0.9901 atm. We need to subtract this from the total pressure to account for the vapor pressure of water (approximately 25.2 torr at 26°C, or 0.0331 atm). So, the final pressure value we will use is 0.9901 atm - 0.0331 atm = 0.957 atm.

Now we substitute the values into the Ideal Gas Law: (0.957 atm) * (0.345 L) = n * (0.08206 L⋅atm/(mol⋅K)) * (302 K). Calculating the number of moles, n, we get approximately 0.014 moles of hydrogen gas present in 345 ml at the given conditions.

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