A 0.630 g sample of the ore is completely dissolved in concentrated hno3(aq). the mixture is diluted with water to a final volume of 50.00 ml. assume that all the cobalt in the ore sample is converted to co2+(aq).
(a) what is the [co2+] in the solution if the absorbance of the sample of the solution is 0.74?
(b) calculate the number of moles of co2+(aq) in the 50.00 ml solution.
(c) calculate the mass percent of co in the 0.630 g sample of the ore.

According to the balanced chemical equation, 2 moles of C2H2 produce 4 moles of CO2. Therefore, 1 mole of C2H2 produces 2 moles of CO2.

At STP, 1 mole of any gas occupies 22.4 L.

So, to produce 8 L of CO2, we need (8/22.4) = 0.3571 moles of CO2.

Since 1 mole of C2H2 produces 2 moles of CO2, we need (0.3571/2) = 0.1786 moles of C2H2.

Finally, using the ideal gas law, we can calculate the volume of C2H2 required at STP:

V = nRT/P = (0.1786 mol)(0.0821 L·atm/mol·K)(273 K)/(1 atm) = 3.87 L

Therefore, 3.87 L of C2H2 are required to produce 8 L of CO2 at STP.

In the hydroboration-oxidation reaction, the nucleophile is borane (BH3), and the reaction is regioselective due to the preference for adding to the less substituted carbon atom of the alkene.

In the given experiment, the nucleophile is the compound or species that donates a pair of electrons to form a new covalent bond with another atom or molecule.

In the context of hydroboration-oxidation, the nucleophile is the boron atom (B) in the reagent BH3 (borane). BH3 acts as a Lewis acid and forms a coordinate covalent bond with the nucleophile, which is typically an alkene.

The reaction is considered regioselective because it exhibits selectivity in the formation of a specific regioisomer. In hydroboration-oxidation reactions, the regioselectivity arises from the nature of the reaction mechanism.

During hydroboration, the boron atom adds to the alkene's least substituted carbon atom, resulting in the formation of an organoborane compound. Subsequent oxidation converts the organoborane to an alcohol.

The regioselectivity is primarily attributed to the preference of the boron atom to add to the carbon atom with fewer alkyl groups attached. This preference is due to the electronic and steric factors involved in the reaction mechanism.

The boron atom acts as an electron-deficient species and is attracted to the electron-rich double bond. However, the steric hindrance caused by the alkyl groups around the double bond influences the selectivity, favoring the addition to the less hindered carbon atom.

Overall, the regioselectivity of the hydroboration-oxidation reaction ensures the formation of the desired regioisomer by selectively adding the boron atom to the less substituted carbon atom of the alkene, leading to the synthesis of the target compound.

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a) Before NaOH: pH ≈ 3.64, After NaOH: Since NaOH is a strong base, it reacts with formic acid to form sodium formate and water; b) Before HCl: pH ≈ 3.64, After HCl: Since HCl is a strong acid, it reacts with sodium formate to form formic acid and water.

To calculate the pH of the formic acid and sodium formate buffer before and after the addition of NaOH and HCl, we can use the Henderson-Hasselbalch equation.

a. Before the addition of NaOH:
The pKa of formic acid is 3.75. Using the Henderson-Hasselbalch equation, the pH before adding NaOH is calculated as:
pH = pKa + log ([salt] / [acid])
pH = 3.75 + log (0.30 / 0.36)
pH ≈ 3.75 - 0.11
pH ≈ 3.64

After the addition of NaOH:
Since NaOH is a strong base, it reacts with formic acid to form sodium formate and water. The moles of formic acid and sodium formate remain the same, but the concentrations change. The concentration of formic acid decreases, while the concentration of sodium formate increases.

b. Before the addition of HCl:
Using the Henderson-Hasselbalch equation, the pH before adding HCl is calculated as:
pH = pKa + log ([salt] / [acid])
pH = 3.75 + log (0.30 / 0.36)
pH ≈ 3.75 - 0.11
pH ≈ 3.64

After the addition of HCl:
Since HCl is a strong acid, it reacts with sodium formate to form formic acid and water. The moles of sodium formate and formic acid remain the same, but the concentrations change. The concentration of sodium formate decreases, while the concentration of formic acid increases.

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The number of atoms in 0.0082g of gold is 2.50 x 10^19 atoms.

What is a molar mass in chemistry?

Molar mass is the mass of one mole of a substance, usually expressed in grams per mole (g/mol). It is a fundamental concept in chemistry that allows us to relate the mass of a substance to the number of atoms or molecules present.

The molar mass of gold (Au) is approximately 197 g/mol. To find the number of atoms in 0.0082 g of gold, we first need to calculate the number of moles of gold present:

moles of gold = mass of gold / molar mass of gold moles of gold = 0.0082 g / 197 g/mol moles of gold = 4.16 x 10^-5 mol

Next, we can use Avogadro's number (6.022 x 10^23 atoms/mol) to convert the number of moles to the number of atoms:

number of atoms = moles of gold x Avogadro's number number of atoms = 4.16 x 10^-5 mol x 6.022 x 10^23 atoms/mol number of atoms = 2.50 x 10^19 atoms

Therefore, there are approximately 2.50 x 10^19 atoms in 0.0082 g of gold.

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In the neutralization reaction, the Brønsted-Lowry conjugate acid-base pairs are the acid HCl and the base OH- as well as the acid H₂O and the base Cl-.

The neutralization reaction involves the formation of two Brønsted-Lowry conjugate acid-base pairs. The acid-base pairs are HCl (acid) and OH⁻ (base), as well as H₂O (acid) and Cl⁻ (base). In this reaction, the acid donates a proton (H+) to the base, resulting in the formation of water and a salt. HCl donates a proton to OH- to form water, while H₂O donates a proton to Cl⁻ to form hydrochloric acid (HCl). The transfer of protons between the acid and base creates the conjugate acid-base pairs.

Brønsted-Lowry acid-base theory describes the transfer of protons (H+) between acids and bases. Acids are proton donors, while bases are proton acceptors. In a neutralization reaction, an acid reacts with a base to form a salt and water.

The acid donates a proton to the base, forming a conjugate base, while the base accepts the proton, forming a conjugate acid. In the given neutralization reaction, HCl is the acid and OH- is the base, forming water. Simultaneously, H₂O acts as an acid, donating a proton to Cl⁻, which acts as a base, forming HCl. Understanding conjugate acid-base pairs is essential in comprehending acid-base reactions and their equilibrium.

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Answer:

The main difference between flowering and nonflowering plants is their method of reproduction. Flowering plants rely on pollination for reproduction, where as nonflowering plants rely on dispersion to continue their life cycle.

The new volume of the nitrogen gas is 88 ml. The correct answer is not listed in the options given, so it is possible that there is a typo in the question or answer choices.

To solve this problem, we can use the ideal gas law equation, PV = nRT. We know the initial pressure (P1 = 2.0 atm), initial temperature (T1 = 45 degrees c = 318 K), and initial volume (V1 = 25 ml) of the nitrogen gas. We can assume the number of moles of nitrogen gas (n) and the gas constant (R) are constant.
First, we need to convert the initial temperature to Kelvin:
T1 = 45 + 273 = 318 K
Next, we can use the ideal gas law to solve for the number of moles of nitrogen gas:
n = (P1V1) / (RT1)
We can then use the same equation to solve for the final volume (V2) at the new conditions:
V2 = (nRT2) / P2
We know the final pressure (P2 = 1.5 atm) and the final temperature (T2 = -10 degrees c = 263 K).
Plugging in the values:
n = (2.0 atm * 25 ml) / (0.0821 L*atm/mol*K * 318 K) = 0.001988 mol
V2 = (0.001988 mol * 0.0821 L*atm/mol*K * 263 K) / 1.5 atm = 0.088 L = 88 ml
Therefore, the new volume of the nitrogen gas is 88 ml. The correct answer is not listed in the options given, so it is possible that there is a typo in the question or answer choices.

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Answer:

Endothermic reactions are chemical reactions in which the reactants absorb heat energy from the surroundings to form products.

Answer:

Chemical reactions that absorb (or use) energy overall are called endothermic. In endothermic reactions, more energy is absorbed when the bonds in the reactants are broken than is released when new bonds are formed in the products.

Answer:

The earth is split into four major layers: the crust, the mantle, the outer core and the inner core

Explanation:

Answer:

Boiling, melting

Explanation:

Physical changes affect the form of a chemical substance.

The solubility of potassium chloride at 90 degrees Celsius is 1.93 M when 144g of KCl is dissolved in 1 dm^3 of water.

To calculate the solubility of potassium chloride (KCl) at 90 degrees Celsius, we need to consider the amount of KCl dissolved in 1 dm^3 (cubic decimeter) of water. Given that we have 144g of KCl, we can convert it to moles by dividing the mass by the molar mass of KCl. The molar mass of KCl is the sum of the atomic masses of potassium (K) and chlorine (Cl), which is 39 + 35.5 = 74.5 g/mol.

Number of moles of KCl = mass / molar mass
Number of moles of KCl = 144g / 74.5 g/mol = 1.93 mol

Now, we know the number of moles of KCl dissolved in 1 dm^3 of water. This is also known as the molarity (M).

Molarity (M) = number of moles / volume in dm^3
Molarity (M) = 1.93 mol / 1 dm^3 = 1.93 M

Therefore, the solubility of potassium chloride at 90 degrees Celsius is 1.93 M when 144g of KCl is dissolved in 1 dm^3 of water.

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Answer:

\({ \tt{kelvin = 273 + celcius \: degree}} \\ { \boxed{ \bf{celcius = kelvin - 273}}}\)

Answer:

To convert Kelvins into Celsius degrees, the formula is K − 273.15 = °C

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The internal temperature rises slowly when the material is isolated from one another, however it rises quickly when the material is bonded because conduction is used for heat transfer.

The mechanical processes known as thermal conduction ask to fall into one of three categories. Conduction. When there is no displacement of matter, the molecules' agitation acts as a carrier for the energy. Convection. When moving material, liquids and gases play a crucial role.

Radiation. when there is no physical contact and energy is delivered by electromagnetic wave radiation. The exterior body may be at a very high temperature while the inner body may be cold because radiation heating is the least effective when the two layers are initially not touching. Thermal conduction, which is how energy is transferred when materials come into contact, causes a large rise in internal temperature.

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The final temperature of the iron chunk would be approximately 69.07 ˚C.

To determine the final temperature of the iron chunk, we can use the equation:

q = m * C * ΔT

where:

q = energy transferred (in joules)

m = mass of the iron chunk (in grams)

C = heat capacity of solid iron (in J/g˚C)

ΔT = change in temperature (in ˚C)

We can rearrange the equation to solve for ΔT:

ΔT = q / (m * C)

Substituting the given values:

q = 70,548 J

m = 384.67 g

C = 0.447 J/g˚C

ΔT = 70,548 J / (384.67 g * 0.447 J/g˚C)

ΔT ≈ 43.25 ˚C

To find the final temperature, we add ΔT to the initial temperature:

Final temperature = Initial temperature + ΔT

Final temperature = 25.82 ˚C + 43.25 ˚C

Final temperature ≈ 69.07 ˚C

Therefore, the final temperature of the iron chunk would be approximately 69.07 ˚C.

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The answer is (e) 70 milliliters.

Let's assume that x milliliters of the 35% saline solution were used.

The total amount of saline in the solution can be calculated as follows:

Saline in 35% solution = 0.35 * x

Saline in 75% solution = 0.75 * 10 (since 10 milliliters of the 75% solution were used)

The total amount of saline in the resulting 40% solution can be calculated as:

Saline in 40% solution = 0.40 * (x + 10)

Since the saline is being mixed, the total saline in the resulting solution is equal to the sum of the saline in the individual solutions:

0.35 * x + 0.75 * 10 = 0.40 * (x + 10)

Simplifying the equation:

0.35x + 7.5 = 0.40x + 4

Subtracting 0.35x and 4 from both sides:

7.5 - 4 = 0.40x - 0.35x

3.5 = 0.05x

Dividing both sides by 0.05:

x = 3.5 / 0.05

x = 70

Therefore, 70 milliliters of the 35% saline solution were used. The answer is (e) 70 milliliters.

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Answer:

1.5 mol of Oxygen will react with 2 mol of Aluminium

The stoichiometry of a chemical reaction, is the relationship between the quantities of reactants and products before, during, and following chemical reactions. This is represented as a ratio of reactants to products.

Consider the following reaction: aA + bB ⇄ cC + dD.

The stoichiometry for this reaction, is the ratio of coefficients:

a : b : c : d. When attempting mole calculations and other quantitative chemistry problems, we are required to follow the stoichiometry always, unless stated otherwise. (This situation would occur in the presence of an excess/limiting reagent).

For the following reaction:

\(\boxed{\rm 4Al_{\,(s)}+3O_{2\,(g)} \rightarrow 2Al_2O_{3\,(s)}}\)

The stoichiometry is 4 : 3 : 2.

∴ moles of O₂ = 3/4 × moles of Al = 3/4 × 2 = 1.5 mol

∴ 1.5 mol of Oxygen will react with 2 mol of Aluminium

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Answer:

C. Electricity

Explanation:

Nuclear fission:

A nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy. 

In nuclear power stations, nuclear fission reactions occur producing heat energy which is used to heat water and produce steam.

The steam is used to spin large turbines that generate electricity.

 Therefore, nuclear power plants use heat produced during nuclear fission reactions to heat water, and the steam generated is used to spin turbines which in turn generate electrical energy through a generator.

Answer:

2AlPO4(aq) + 3Mg(s) -------> Mg3(PO4)2(aq) + 2Al(s)

Explanation:

The principle of writing balanced chemical reaction equations states that; the number of atoms of each element on the right hand side of the reaction equation must be equal to the number of atoms of the same element on the left hand side of the reaction equation.

The reaction is between aqueous aluminum phosphate reacts and solid magnesium to produce solid aluminum and aqueous magnesium phosphate. The equation is represented as follows;

2AlPO4(aq) + 3Mg(s) -------> Mg3(PO4)2(aq) + 2Al(s)

The chemical formula of water is H2O. This means that each water molecule contains 2 hydrogen atoms.

To calculate the mass of hydrogen in 7.92*10^23 molecules of water, we need to first determine the total number of hydrogen atoms in those molecules.

Since each water molecule contains 2 hydrogen atoms, the total number of hydrogen atoms in 7.92*10^23 molecules of water is:

2 hydrogen atoms/molecule x 7.9210^23 molecules = 1.58410^24 hydrogen atoms

Next, we can calculate the mass of hydrogen in those atoms using the atomic mass of hydrogen, which is approximately 1.008 g/mol.

Mass of hydrogen = number of hydrogen atoms x atomic mass of hydrogen

Mass of hydrogen = 1.584*10^24 x 1.008 g/mol

Mass of hydrogen = 1.596672*10^24 g

Therefore, the mass of hydrogen in 7.9210^23 molecules of water is approximately 1.59667210^24 g.

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0.25 moles of O2 is needed to produce 14.2 grams of P4O10 from P.

In order to calculate the number of moles of O2 needed to produce 14.2 grams of P4O10 from P, we need to use the equation for the reaction:

P + 5O2 → P4O10

We can calculate the number of moles of O2 needed by using the molar mass of P4O10, which is 284 g/mol. First, we need to calculate the number of moles of P4O10 present in 14.2 grams:

14.2 g/ 284 g/mol

= 0.05 mol.

Now, we can use the mole ratio between P and O2 to calculate the number of moles of O2 needed. The mole ratio is 5:1, meaning that for every 5 moles of O2, 1 mole of P is needed. Therefore, to get 0.05 moles of P4O10 from P, we need 0.05 x 5 = 0.25 moles of O2.

In conclusion, 0.25 moles of O2 is needed to produce 14.2 grams of P4O10 from P.

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Balanced equation:-

\(\\ \sf\longmapsto C+O_2\longrightarrow CO_2\)

Hence

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

\(n = \frac{N}{L} \\ \)

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

\(n = \frac{4.23 \times {10}^{25} }{6.02 \times {10}^{23} } \\ = 70.265780...\)

We have the final answer as

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Answer:

The concentration of the solution is 5.8168 × \(10^{-4}\) mol.\(dm^{-3}\)

Explanation:

Here, we want to calculate the concentration of the solution.

The unit of this is mol/dm^3

So the first thing to do here is to calculate the number of moles of the solute present, which is the number of moles of AlCO3

The number of moles = mass/molar mass

molar mass of AlCO3 = 27 + 12 + 3(16)  = 27 + 12 + 48 = 87g/mol

Number of moles = 33.4/87 = 0.384 moles

This 0.384 moles is present in 660 L

x moles will be present in 1 dm^3

Recall 1 dm^3 = 1L

x * 660 = 0.384 * 1

x = 0.384/660 = 0.00058168 = 5.8168 * 10^-4 mol/dm^3

For presenting the polar covalent bond, the correct option is A.

It existed at the time when atoms with distinct electronegativities share electrons should be in a covalent bond. The presenting of the polar covalent bond represent the two atoms electronegativities that it is two atoms should not be equal.

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The statements that are concerning gas pressure is/are correct :

1) Gas pressure arises from collisions of gas molecules with the walls of the container holding the gas.
2) Increasing the number of gas molecules within a container increases the number of collisions with the walls of the container, thereby increasing the gas pressure.
3) As the temperature of a gas increases, gas molecules exert more force on the walls of their container.

Your answer: All three statements are correct.

Explanation:
1) Gas pressure is a result of gas molecules colliding with the walls of their container, transferring their momentum and creating force.
2) When you increase the number of gas molecules in a container, the number of collisions with the walls also increases, which in turn increases the gas pressure.
3) As the temperature of a gas increases, the kinetic energy of the gas molecules increases, leading to more forceful collisions with the walls of the container and a higher gas pressure.

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Answer: There are \(3.011 \times 10^{23}\) atoms present in 0.500 mol of \(CO_{2}\).

Explanation:

According to the mole concept, there are \(6.022 \times 10^{23}\) atoms present in 1 mole of a substance.

In a molecule of \(CO_{2}\) there is only one carbon atom present. Therefore, number of carbon atoms present in 0.500 mol of \(CO_{2}\) are as follows.

\(1 \times 0.500 \times 6.022 \times 10^{23}\\= 3.011 \times 10^{23}\)

Thus, we can conclude that there are \(3.011 \times 10^{23}\) atoms present in 0.500 mol of \(CO_{2}\).

Based on the description given above, the  student discovers an arachnid with a segmented abdomen long legs and a tail with no stinger called option A: Whip Scorpion

The names "whip scorpion" and "vinegaroon" relate to the creatures' resemblance to real scorpions and the presence of a whip-like tail, respectively. The latter name refers to the creatures' capacity to eject an acrid, vinegar-smelling substance during an attack.

Therefore, onw should know that whip scorpions are arachnids that resemble real scorpions in appearance but lack their poisonous sting. They are not poisonous, but they can spray an acidic mixture that smells like vinegar.

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A student discovers an arachnid with a segmented abdomen, long legs, and a tail with no stinger.

The student uses the dichotomous key below to identify it.

1. a) Abdomen segmented.............go to 2

b) Abdomen not segmented ......go to 4

2. a) Abdomen with tail....................go to 3

b) Abdomen without tail...............go to 5

3. a) Tail with stinger..........................Scorpion

b) Tail without stinger.....................Whip scorpion

4. a) Legs longer than body.............Daddy Long Legs

b) Legs not longer than body……….Wind scorpion

5. a) Covered with spines .......................Mite

b) Few spines.....................................Tick

answer choices

Whip Scorpion

Daddy Long Legs

Mite

Tick

Answer: Raw meat, poultry and seafood. Feces may get onto raw meat and poultry during the butchering process. ...

Raw eggs. ...

Fruits and vegetables.

Explanation: