The hydroxyl end groups of a sample (2. 00 g) of linear poly(ethylene oxide) were acetylated by reaction with an excess of acetic anhydride (2. 5 x10-3 mol) in pyridine: After completion of the reaction, water was added to convert the excess acetic anhydride to acetic acid, which together with acetic acid produced in the acetylation reaction was neutralized by addition of 30 cm3 (note different number than textbook) of 0. 100 mol/dm3 solution of sodium hydroxide. Calculate the number average molar mass for the sample of poly(ethylene oxide) given that each molecule has two hydroxyl end groups. Poly(ethylene oxide):

Answer:

Magnesium, strontium, and barium belong to group 2A of the periodic table.

A change that produce matter with a different composition is a chemical change.

The average atomic mass of carbon is 12.09 amu.

The atomic mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope. (Atomic mass is also referred to as atomic weight, but the term "mass" is more accurate.)

Atomic mass = Mass of protons + Mass of neutrons + Mass of electrons.

To calculate the number of atoms in a sample, divide its weight in grams by the amu atomic mass from the periodic table, then multiply the result by Avogadro's number: 6.02 x 10^23.

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Answer:12.011

Explanation:

this is 100% right

During the cell cycle, compounds called cyclins increase and decrease in a regular pattern. They regulate the stages of cell division and growth.

Cell cycle development is regulated in element by way of the sequential pastime of various cyclins. The cyclins are regulatory subunits that bind, prompt and provide substrate specificity for their catalytic companion serine-threonine kinases, collectively called cyclin-established kinases.

Cyclins are a family of proteins that don't have any enzymatic interest of their personal however spark off CDKs through binding to them.

S cyclins are involved inside the induction of DNA replication and early stages of mitosis. Their stages upward push at the beginning of S phase and fall in early mitosis.

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Balanced molecular equation-

Sometimes a balanced equation will suffice to refer to a molecular equation.

NiCl₂ (aq) + Na₂S (aq) -----> NiS (s) + 2NaCl (aq)

Complete ionic equation-

A chemical equation known as an ionic equation expresses the electrolytes in aqueous solution as dissociated ions.

Ni²⁺ + 2Cl⁻ + 2Na⁺ + S²⁻------> NiS + 2Na⁺ + 2Cl⁻

Net ionic equation

Ni²⁺ + 2Cl⁻ + 2Na⁺ + S²⁻------> NiS + 2Na⁺ + 2Cl⁻

or

Ni²⁺ (aq) + S²⁻ (aq)-----> NiS (s)

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Answer:

Aquatic plants that live underwater have leaves with large air pockets inside that allow the plant to absorb oxygen from the water.

Answer:

. Plant adaptations are changes that help a plant species survive in its environment. Aquatic plants that live underwater have leaves with large air pockets inside that allow the plant to absorb oxygen from the water. The leaves of aquatic plants are also very soft to allow the plant to move with the wave.

Explanation:

Answer:

The molecular structure affects solubility mainly biased on its polarity or bonded ions.

Explanation:

Polar molecules will better interact with the water molecules and will dissolve easier. Nonpolar molecules can dissolve if they are small enough, however they don't interact well with the polar molecules. Bonded ions, such as NaCl split into a cation Na and an anion Cl which the positive charge on the Na will be attracted to the oxygen, and the negatively charged Cl will be attracted to the positive Hydrogen.

**Remember this rule, like dissolves like, meaning nonpolar dissolves nonpolar and polar dissolves polar.

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Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickly. The ethanol version is the most widely used due to the low cost and relatively low hazard posed by the liquid in case of breakage.

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Answer:

1-There Must be some displacement in the direction of force.                                                  2-Angle between force and displacement is 0°.                                                                            

Answer:

equal to - it's opposite but equal energy is the third law

In 0.75 moles of caffeine, there are a total of 6 carbon atoms, 7.5 hydrogen atoms, 3 nitrogen atoms, and 1.5 oxygen atoms.

To determine the total number of atoms in 0.75 moles of caffeine, we need to consider the molecular formula of caffeine, which is C8H10N4O2. The molecular formula provides the ratios of each element present in the compound. By multiplying the number of atoms in each element by the corresponding coefficient in the molecular formula, we can calculate the total number of atoms. In this case, there are 8 carbon (C) atoms, 10 hydrogen (H) atoms, 4 nitrogen (N) atoms, and 2 oxygen (O) atoms in each molecule of caffeine. Multiplying these values by 0.75 moles will give us the total number of atoms in 0.75 moles of caffeine.

The molecular formula of caffeine, C8H10N4O2, provides the number of atoms for each element present in one molecule of caffeine. In this case, there are 8 carbon (C) atoms, 10 hydrogen (H) atoms, 4 nitrogen (N) atoms, and 2 oxygen (O) atoms.

To calculate the total number of atoms in 0.75 moles of caffeine, we need to multiply the number of atoms for each element by the coefficient in the molecular formula, and then multiply that by the number of moles (0.75 moles).

For carbon (C): 8 atoms x 0.75 moles = 6 atoms (since there are 8 carbon atoms in one molecule of caffeine).

For hydrogen (H): 10 atoms x 0.75 moles = 7.5 atoms (since there are 10 hydrogen atoms in one molecule of caffeine).

For nitrogen (N): 4 atoms x 0.75 moles = 3 atoms (since there are 4 nitrogen atoms in one molecule of caffeine).

For oxygen (O): 2 atoms x 0.75 moles = 1.5 atoms (since there are 2 oxygen atoms in one molecule of caffeine).

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The overall reaction between aqueous ammonia and solid copper(II) phosphate can be represented as follows: \($\mathrm{Cu_3(PO_4)_2 (s) + 4NH_3 (aq) \rightleftharpoons [Cu(NH_3)_4]^{2+} (aq) + 2PO_4^{3-} (aq)}$\)

Let's start by writing the reactions corresponding to Ksp and Kf:

Reaction for the formation of the insoluble copper(II) phosphate:

\($\mathrm{Cu^{2+} (aq) + PO_4^{3-} (aq) \rightarrow Cu_3(PO_4)_2 (s)}$\)

Reaction for the formation of the complex ion \($\mathrm{[Cu(NH_3)_4]^{2+}}$\):

\($\mathrm{Cu^{2+} (aq) + 4NH_3 (aq) \rightleftharpoons [Cu(NH_3)_4]^{2+} (aq)}$\)

To derive the overall reaction between copper(II) ion and aqueous ammonia, we can combine these reactions. Since the complex formation with ammonia occurs in the presence of the copper(II) ion, we can use the fact that the copper(II) ion is in equilibrium with the small amount of free copper(II) ions:

\($\mathrm{Cu^{2+} (aq) \rightleftharpoons Cu^{2+} (aq)}$\)

By combining the two reactions, we can cancel out the common species \($\mathrm{Cu^{2+}}$\):

\($\mathrm{Cu_3(PO_4)_2 :(s) + 4NH_3 :(aq) \rightleftharpoons [Cu(NH_3)_4]^{2+} :(aq) + 2PO_4^{3-} :(aq)}$\)

This is the overall chemical reaction that occurs between aqueous ammonia and solid copper(II) phosphate.

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Answer:

cation - electron loss hence positive charge

anion - electron gain hence negative charge

The given terms are correctly paired thus: anion is to electron gain while cation is to electron loss.

Ionic bond formation is defined as the formation of an ionic bond during a chemical reaction whereby an atom losses electrons while another gains electrons through transfer of these electrons.

For example in the formation of the compound NaCl. Sodium is the element that donates an electron from its outermost shell to chloride. Therefore, the sodium atom is the cation.

Also the chloride element would accept electron from the sodium, therefore, it is called the anion.

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Answer:

because battery have it's own voltage in it's composition

The type of radioactive decay that results in no change in the mass number or the atomic number of the decaying nuclide is known as gamma decay.

Gamma decay occurs when an excited nucleus emits a gamma ray, which is a high-energy photon, in order to release excess energy and return to a lower energy state. Unlike alpha and beta decay, which involve the emission of particles that alter the atomic and/or mass number of the nuclide, gamma decay does not involve the emission of particles but rather the emission of energy in the form of a gamma ray.

As a result, the atomic number and mass number of the decaying nuclide remain the same after gamma decay. Gamma decay is an important process in nuclear medicine, as it is used in imaging techniques such as PET scans to detect the presence and location of radioactive isotopes in the body.

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The initial investment is $300 million, and the project is planned to operate for A0 years with an estimated salvage value of $20 million.

To calculate whether the city can recover the capital cost and other operating costs for the water-desalination plant, you can follow these step-by-step calculations:

Step 1: Calculate the annual revenue from selling water:

First, convert the water production from gallons to acre-feet:

Water production per day = 50 million gallons

Water production per year = 50 million gallons * 365 days = 18.25 billion gallons

Water production in acre-feet = 18.25 billion gallons / 325,851 gallons per acre-foot

Calculate the annual revenue from selling water:

Annual revenue = Water production in acre-feet * Price per acre-foot

Step 2: Calculate the annual operating and maintenance costs (excluding energy cost):

Operating and maintenance costs in the first year = $15 million

Calculate the annual operating and maintenance costs for subsequent years:

Operating and maintenance costs in year n = Operating and maintenance costs in year n-1 * (1 + Growth rate)

Step 3: Calculate the annual energy cost:

Energy cost per 10,000 gallons = $0.90

Calculate the annual energy cost:

Annual energy cost = Water production in gallons / 10,000 gallons * Energy cost per 10,000 gallons

Step 4: Calculate the annual cash flow:

Annual cash flow = Annual revenue - Annual operating and maintenance costs - Annual energy cost

Step 5: Calculate the present value of cash flows:

Use the present value formula to calculate the present value of cash flows over the A0 years:

PV = Annual cash flow / (1 + Interest rate)^Year

Step 6: Calculate the net present value (NPV):

NPV = PV - Initial investment

Step 7: Determine if the project is financially feasible:

If the NPV is greater than or equal to zero, the project is financially feasible and can recover the capital cost and other operating costs. If the NPV is negative, the project may not be able to recover the costs.

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Answer:

copper cathodes are normally referred to when talking about copper. Cathode is the purest form of copper and is the feedstock used to produce copper wire, cable, sheet, strip, tube, etc.

Explanation:

Answer:

300 mL

Explanation:

the unit formula of calcium phosphate is Ca3(PO4)2

molar mass of Ca3(PO4)2 = (3×40 + 2×31 + 8×16) g/mol = 310 g/mol

n = m/M = 35 g/(310 g/mol)

c = n/V

V = n/c = [35 g/(310 g/mol)]/0.375 mol/L

V = 0.30 L = 300 mL

The statement "The -ide ending in nitrogen dioxide tells you that this is an ionic compound" is false. Nitrogen dioxide is actually a covalent compound, meaning it is composed of molecules held together by shared electrons.

The -ide ending typically indicates a binary compound consisting of two elements, but nitrogen dioxide (NO2) is a covalent compound, not an ionic compound.

In an ionic compound, electrons are transferred between atoms, whereas in a covalent compound like nitrogen dioxide, electrons are shared between the nitrogen and oxygen atoms.

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Answer:

they end up bouncing against each other instead of merging together

Explanation:

Answer:

Clearing Land for a highway

Explanation:

The other examples are that of naturally occurring disasters and most life in that region have ways to regrow and repopulate in the case of those disasters. While a highway is a manmade object and interrupts the environment to the point that the new animals will not know how to deal with it. That is also why there are a lot of dead deer are found on the side of the road when a new highway is built.

Clearing land for a highway would most likely cause an ecosystem to have the lowest biodiversity and population sizes 3 years later. Therefore, option D is correct.

Biodiversity refers to the variety of life that can be found in a given area, including animals, plants, fungi, and even microorganisms such as bacteria. Each of these species and organisms collaborate in ecosystems to maintain balance and support life, much like an intricate web.

Every one of these exists in delicate balance and lives and works together in ecosystems to sustain and support life on Earth.

Typically, three levels of biodiversity are discussed: genetic diversity, species diversity, and ecosystem diversity. Genetic diversity refers to the various genes found in all plants, animals, fungi, and microorganisms. It can occur both within and between species.

Thus, option D is correct.

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some regions of a polypeptide may coil or fold back on themselves. this is called secondary structure , and the coils or folds are held in place by hydrogen bonds

After translation, primary structure is just the arrangement of amino acids. The interactions between the carbonyl, amino, and side groups of the amino acid polymer backbone inside the chain result in the secondary structure of proteins. These interactions are primarily fueled by hydrogen bonds, which result in the formation of alpha helices and beta sheets, which are the primary features of proteins' secondary structures.

To create a useful three-dimensional structure, tertiary structure requires more interactions within the protein chain. Disulfide bonds between cysteines, hydrophobic contacts, ionic bonding, and dipole-dipole interactions are a few of these interactions. To create a useful, three-dimensional protein structure, several protein chains interact in quaternary structure.

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Avogadro's number is approximately 6.022 × 10^23 formula units per mole.

Given that there are 3.0 × 10^23 formula units of KI, we can calculate the number of moles of KI by dividing the number of formula units by Avogadro's number:

Number of moles = (3.0 × 10^23 formula units) / (6.022 × 10^23 formula units/mol)

Number of moles ≈ 0.498 mol

To find the mass of KI, we can use the molar mass of KI:

Mass of KI = Number of moles × Molar mass

Mass of KI = 0.498 mol × 166 g/mol

Mass of KI ≈ 82.668 g

Therefore, there are approximately 82.668 grams of KI in the sample.

The literature value range of 185-186oc falls within the melting point range of 180-195oc obtained from the experiment. Therefore, it can be concluded that the purified compound is most likely the desired compound. However, it is important to note that the melting point alone cannot confirm the identity of a compound.

Other analytical techniques such as spectroscopy should also be used to verify the identity of the compound. The value of a compound refers to its worth or usefulness in a particular application. In this case, the value of the compound is based on its identity and purity, which can be determined through various analytical techniques.

Overall, the experiment was successful in purifying the compound and obtaining a melting point range that suggests the compound is the desired one.

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Answer:

HOPE I HELPED!

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Matter is composed of tiny particles called _Atoms and molecules_.

What is the difference between states of matter and phases of matter? -The difference between  states of matter and phases of matter is that the state of matter is the state of a particular compound in a physical system whereas phase is a set of states within such a system.

Solid: The solid state is one of the fundamental states of matter. Solids differ from liquids and gases by the characteristic of rigidity.

Liquid: The molecules in a liquid are closely packed due to weak intermolecular forces. These forces are weaker than solids but stronger than that of gases.

Gas: Molecules floating all over the place

What causes matter to change states? - Changing states of matter occur when matter loses or absorbs energy.

What is temperature? - The degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch.

What instrument is used to measure temperature? - Thermometers

What happens when two substances of different temperatures come in contact with each other? - When two substances having different temperatures are introduced or kept together, heat energy flows from a substance at higher temperature to a substance at lower temperature.

What happens when a substance moves below its freezing point? - Evaporation can take place below the boiling point of a substance.

What happens when it moves above its boiling point? - Boiling is the process by which a liquid turns into a vapor when it is heated to its boiling point.

A change of state from solid to liquid is called _melting___.

What is the difference between vaporization and evaporation? - Vaporization is the process of conversion of solid or liquid into gaseous form while evaporation is the change of a liquid into gaseous form.

What is an example of sublimation? - Vaporization of frozen carbon dioxide (dry ice) at ordinary atmospheric pressure and temperature.

What is an example of condensation? - Having a cold soda on a hot day, the can "sweats."

During a phase change, the temperature remains __constant__. After the change of state occurs, the temperature _can rise again_.

Describe the three methods of thermal energy transfer:

Conduction: For conduction to take place between two objects, they must be touching each other.

Convection: The circulatory motion that occurs in a fluid at a nonuniform temperature owing to the variation of its density and the action of gravity

Radiation: Radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium.

What are electromagnetic waves? - Composition of oscillating electric and magnetic fields.

What are some examples of conductors and insulators? - Many metals, such as copper, iron and steel, are good electrical conductors. That is why the parts of electrical objects that need to let electricity pass through are always made of metal.

What are the characteristics of conductors and insulators? -  

An electrical insulator is a material in which the electron does not flow freely or the atom of the insulator have tightly bound electrons whose internal electric charges do not flow freely; very little electric current will flow through it under the influence.  

In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electrical current) in one or more directions.

How does thermal energy affect different materials? - Thermal energy affects different materials by the movement of the tiny particles, which transfers from one object to another, aka heat.

Explanation: