What is the molality of a solution prepared by dissolving 86.9 g of diethyl ether, c4h10o (74.12 g/mol), in 425 g of benzene, c6h6?

Answer:

When water dissolves a substance, the water molecules attract and “bond” to the particles (molecules or ions) of the substance causing the particles to separate from each other. The “bond” that a water molecule makes is not a covalent or ionic bond. It is a strong attraction caused by water’s polarity.

Explanation:

Answer:Flame tests are used to help identify substances used in murders

Explanation:

The number of atoms present in the sample is 2.163 x 10²² atoms.

The mass of the sample is 0.25 g.

The number of atoms present in the sample is calculated as follows;

E = nhf

where

n = E/hf

n = (8600) / (6.626 x 10⁻³⁴ x 6 x 10¹⁴)

n = 2.163 x 10²² atoms

6.02 x 10²³ atoms of Lithium = 6.9 g

2.163 x 10²² atoms = ?

= (2.163 x 10²² atoms x 6.9 g) /(6.02 x 10²³ atoms )

= 0.25 g.

Thus, the number of atoms present in the sample is 2.163 x 10²² atoms. The mass of the sample is 0.25 g.

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By interpolation, the volume of hydrogen gas produced is 800 mL.

The reaction between zinc granules and sulfuric acid solution to produce hydrogen gas is given by the equation below:

In the given reaction, zinc displaces hydrogen from solution to form zinc ions and hydrogen gas is evolved.

The volume of hydrogen gas evolved per unit time, and hence the reaction rate depends on the concentration of the sulfuric  acid. The higher the concentration of the sulfuric acid, the greater the volume of hydrogen gas produced per unit time.

Considering the graph of the given volume of hydrogen produced against time for the reaction carried out by by dropping 2.5 grams of zinc in 100 mL of sulfuric acid solution with the same concentration;

By interpolation, the volume of hydrogen gas produced is 0.8 L or 800 mL.

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The action of investigating something or someone; formal or systematic examination or research.

Scientific investigation is what people like you and me use to develop better models and explanations for the world around them.

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Calculate the moles in each reactant

Acetic Acid (.231 mol/L)(0.125L)=  2.887 x 10^-2 mol AA

NAOH (.209mol/L)(.037L)= 7.733 x 10^-3 mol NaOH

As you can see, we have more AA and less NaOH, so NaOH is the limiting reactant.

NaOH + CH3COOH -> NaCH3COOH + H2O​

start: 4.5 mmol, 8.75mmol, 0, n/a

change: -4.5 mmol, -4.5mmol, 4.5mmol, n/a

after rxn: 0, 4.25 mmol, 4.5mmol, n/a​

Now your HH equation

pKa + log(conjugate base/acid) = 4.75 + log(4.5x10^-3 / 4.25x10^-3) =

pH = 4.76

The Henderson-Hasselbalch equation in chemistry and biology connects the pH of a weak acid solution to its acid dissociation constant, Ka, and the ratio of the concentrations of the acid and its conjugate base in equilibrium.

When both the pH of the solution and the ratio of ionized to unionized forms are known, the Henderson Hasselbalch equation can be used to calculate the pKa.

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The balanced half reaction for reduction of the permanganate ion,  to manganese ion,  is shown below:

[tex]MnO_{4^{-} }[/tex] + 8[tex]H^{+}[/tex] + 5e- → [tex]Mn^{2+}[/tex] +  [tex]H_{2} O[/tex]

The portion of an overall reaction that represents either an oxidation or a reduction separately is known as a half-reaction.

A redox reaction can only be fully described by two half-reactions, one oxidation and one reduction.

The chemical compound that contains the manganate (VII) ion is known as permanganate. Because manganese is in the +7 oxidation state and is rapidly reduced and oxidised by other elements, the permanganate(VII) ion is a potent oxidising agent.

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c) 2-hydroxypropanoic acid is the correct Iupac name compound.

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A solution is an example of a homogenous mixture. The correct option is b.

A homogeneous mixture is one in which the composition is consistent throughout. Because the dissolved salt is evenly distributed throughout the salt water sample, the salt water is homogeneous.

A heterogeneous mixture is one in which the composition varies throughout the mixture. Vegetable soup is a diverse concoction.

A solution is a uniform mixture of one or more dissolved solutes in a solvent. It should be noted that the solvent is the most abundant substance.

There are numerous solutions available. A solute, for example, can be a gas, a liquid, or a solid.

Thus, the correct option is b.

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Answer:

sublimation:heat taken in

condensation:heat given out

evaporation:heat taken in

boiling:heat taken in

melting:heat taken in

freezing:heat given out

Processes listed can be classified into two groups based on whether heat is taken in or given out by the particles.Heat is taken in melting,evaporation, sublimation while heat is given out in boiling,condensation and freezing.

Heat taken in by the particles:

1. Sublimation: This process occurs when a substance changes from a solid directly to a gas without passing through the liquid phase. Heat is absorbed to break the intermolecular forces holding the particles in the solid phase.

2. Evaporation: This process happens when a liquid changes into a gas at temperatures below its boiling point. Heat is absorbed from the surroundings to overcome the intermolecular forces between the liquid particles.

3. Melting: Melting occurs when a solid substance changes into a liquid. Heat is absorbed to break the intermolecular forces holding the particles in the solid phase.

Heat given out by the particles:

1. Condensation: Condensation occurs when a gas changes into a liquid. Heat is released to the surroundings as the gas particles lose energy and come together to form liquid droplets.

2. Boiling: Boiling is the process where a liquid changes into a gas throughout its entire volume. Heat is released to the surroundings as the liquid particles gain energy and escape the liquid phase.

3. Freezing: Freezing is the process where a liquid changes into a solid. Heat is released to the surroundings as the liquid particles lose energy and arrange themselves into a regular pattern.

Thus, heat is taken in melting,evaporation, sublimation while heat is given out in boiling,condensation and freezing.

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If phosphorus with 15 neutrons, the mass number of an isotope of phosphorus is 31.

Isotopes are two or more types of atoms that have the same atomic number and position on the periodic table but differ in the number of nucleons due to the different number of neutrons in the nucleus.

An isotope is one of two or more atomic types of a chemical element that have the same atomic number and position on the periodic table and nearly identical chemical behavior, but different atomic masses and physical properties.

If two atoms have different numbers of protons, they are different elements. However, two atoms with the same number of protons and different number of neutrons are called isotopes. Two terms used to identify nuclides isotopes are atomic number and mass number.

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Answer: The brown bear spreads berry and plant seeds in its scat.

Explanation:

In order to prepare a formic acid buffer with a pH of 4.77, a solution with a mole fraction of 10.0 mol HCOONa to 1.0 mol HCOOH is used.

Because formic acid is a weak acid with a pH close to 4.77, try to prepare a formic acid buffer with a little bit more sodium formate than formic acid.

pKa of formic acid is -log (1.7 x 10-4) = 3.77. A formic acid buffer with the necessary pH should be created by combining 10 moles of formate anion with 1 mole of formic acid. Each of these concentrations can be used to modify buffer capacity.

pH = pKa + log [HCOOH]

4.77 = 3.77 + log [HCOOH]

1 = log [HCOOH]

HCOOH = antilog 1

HCOOH = 10

Therefore, the ratio of HCOONa to HCOOH is 10:1

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0.265 amperes are required to deposit of lead metal.

m(Pb) = 0.229 g; mass of lead metal

t = 802 s; time of the reaction

n = 2; number of moles electron involved in electrolysis

F = 96485 C/m; the Faraday's constant

M(Pb) = 207.2 g/mol; the molar mass of the lead

Electrolysis is a chemical methode that uses electric currents for chemical reactions.

To solve this problem, we need Faraday's law of electrolysis:

I = m×n×F / t×M

I = 0.229 g × 2 × 96485 C/m / 802 s × 207.2 g/mol

I = 0.265 A, the current

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The substance that will give an aqueous solution of pH < 7 is (e) NH₄Br.

a) Balanced chemical equation for the reaction of sodium carbonate with water: Na₂CO₃ + 2H₂O → 2NaOH + H₂CO₃

Hydrolysis of this salt gives strong base (NaOH) and weak acid (H₂CO₃), so pH is greater than 7

b) Hydrolysis of sodium acetate gives strong base (NaOH) and weak acid (CH₃COOH), so pH is greater than 7

c) Hydrolysis of potassium gives strong base (KOH) and strong acid (HI), so pH is equal to 7

d) Methanol is neutral, pH is equal to 7

e) Hydrolysis of ammonium bromide gives weak base (NH₄OH) and strong acid (HBr), so pH < 7.

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Answer:

Flour is heterogeneous mixture.

Explanation:

Because you can see the different parts of the mixture,And they're normally not uniformly mixed.

Answer:

Explanation:

The net force is 10-7= 3N and the car moves in the direction of the greater force applied i.e. towards the green arrow or the right side

The number of radioactive nuclei in a particular sample decreases to one-eighth of its original number in 9 days. The half-life of these nuclei is 3 days.

According to radioactive decay law,

n(t) = No [tex]e^{-kt}[/tex]

where n is number at t and No is starting number

when t = 9, n/No = 1/8 = 0.125

so

0.125 =  [tex]e^{-k9}[/tex]

ln 0.125 = -9 k

k = 0.231

So,

half life = [tex]t\frac{1}{2}[/tex] = 0.693/k

half life = [tex]t\frac{1}{2}[/tex] = 0.693/0.231

half life = [tex]t\frac{1}{2}[/tex] = 3days

Therefore, when the number of radioactive nuclei in a particular sample decreases to one-eighth of its original number in 9 days. The half-life of these nuclei is 3 days.

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Answer:

Element: found on periodic table....

Polymer: multiple monomers....

Monomer: one-SINGLE...

Explanation:

The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change

The molecular formulas of maleic and fumaric acids are identical, but fumaric acid is a trans isomer while maleic acid is a cis isomer. The two acids have different physical properties even though they have the same molecular structure.

The melting point of fumaric acid is higher than that of maleic acid. In this case, polarity is much less critical than intermolecular hydrogen bonding in determining the relative stability of the crystal lattice and, consequently, the melting temperature of both acids. The carboxyl groups in fumaric acid can hydrogen bond with their neighbors, whereas the carboxyl groups in maleic acid form an intramolecular hydrogen bond. It requires more effort to break the bonds in the trans isomer than in the cis isomer because of the efficient packing structure of fumaric acid. Since fumaric acid has strong intermolecular forces, its melting point is higher.

The cis configuration, dipole-dipole interaction, and hydrogen bonding of the molecule make maleic acid polar, which makes it soluble in water. Because water is also polar, it can dissolve quickly in it. Fumaric acid is a non-polar molecule, but is not very soluble in water, despite the instantaneous induced dipole that the London Dispersion forces have for the molecule.

After losing the H⁺ ion, malic acid's cis isomer can create intramolecular H bonds, which makes the conjugate base more stable than the trans form (Fumaric acid).

Maleic acid has a higher tendency to lose H⁺ than fumaric acid because intramolecular H-bonding stabilizes the conjugate base by H-bonding, as shown in the first and second figures of the image given below:

Because maleic acid contains intramolecular H-bonding, fumaric acid has a lower pKa₂ than maleic acid when the second H is taken out.

As the acidity rises, the value falls because pKa is the negative logarithm of Ka. Maleic acid has a higher initial dissociation constant than fumaric acid as a result of stable conjugate base synthesis, which increases the former's acidity. Due to the structures of the singly dissociated ions, fumaric acid undergoes the second dissociation more quickly. Fumaric acid is a simple two distinct carboxylate group that dissociates relatively separately.

Maleic acid, on the other hand, only undergoes one dissociation to form a more robust resonant ring structure. The remaining hydrogen can now alternately bond to the oxygen in positions 2 and 3 to form an alternating 3 Center bond because it is a 1,4 dicarbonyl with an alkene between those two positions. The alternating 3 Center bond creates a seven-part aromatic ring because an alkene is located next to it. The conjugate base of maleic acid is stabilized and has fewer acidity thanks to aromatic rings. Look at the image below, specifically the third number figure.

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The ratio of the hydrogen masses in the compounds is 2: 3(Option A).

We know that compounds are composed of atoms and that compounds are formed by the combination of atoms. According to the atomic theory, the combination of the atoms with each other to form compounds occurs in a definite ratio.

From the law of multiple proportions, if two elements combine in such a way that they could lead to the formation of more than one type of compound, the combination occurs in such a way that masses of the second element that combines with first element are in simple ratios.

We can see from the statements in the complete question that the ratio of the hydrogen masses in the compounds is 2: 3(Option A).

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A tiny permanent magnet is always susceptible to demagnetization or having the polarity of the magnet reversed by lightning.

Even a permanent magnet is sensitive to induction, which can cause its polarity to change and become stronger, weaker, or even reversed.

Not just in multicellular creatures but also in individual cells and subcellular structures, polarity enables the development of functional complexity. Polar organisation enables physical relationships between areas with various functions in a way that supports function integration across the entire organism.

The polarity of water causes hydrogen bonds to form when adjacent water molecules are drawn to one another by their opposing charges. Other polar molecules and ions, such as many biomolecules including sugars, nucleic acids, and certain amino acids, are likewise drawn to or attracted by water.

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The sample density is 690 kg/m³.

We need to know about the density to solve this problem. Density is a unit that measures how dense an object is. Density can be measured by dividing mass by volume. It can be written as

ρ = m / V

where ρ is density, m is mass and V is volume

From the question above, we know that

m = 1.20 gram

V = 1.73 cm³

By substituting the following parameters, we get

ρ = m / V

ρ = 1.2 / 1.73

ρ = 0.69 g/cm³

Convert to SI unit (kg/m³)

ρ = 0.69 g/cm³

ρ = 0.69 x 10¯³ kg/ 10¯⁶ m³

ρ = 690 kg/m³

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(1) If chlorine gas is bubbled through an aqueous solution of sodium astatide, the result is elemental iodine and aqueous sodium chloride solution.

(2) No chemical change is observed when astatine is added to an aqueous solution of potassium iodide.

(1) Aqueous sodium chloride salt is created when chlorine gas and sodium astatide combine in the proper circumstances. An electron is taken from the sodium and given to the chlorine. The electrostatic interaction between the particles makes this reaction more favorable. Large amounts of heat and light are emitted during the process.

So, the result is elemental iodine and aqueous sodium chloride solution.

(2) Astatine is present below iodine in the periodic table in group 7 and it is less reactive than iodine, so no chemical change is observed when astatine is added to an aqueous solution of potassium iodide.

Hence, no displacement by astatine takes place.

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The independent variable that we change in an experiment.

The correct option C.

A variable that is independent is precisely what it seems like. It is an independent variable that has no bearing on the other factors you are trying to evaluate. For example, age may be an independent variable. Time is a popular independent variable since it is undisturbed by any dependant environmental influences.

You can have independent or dependent variables. Other variables have an impact on the value of independent variables, while dependent variables have an impact on the value of independent variables. A hypothesis identifies an anticipated connection between two variables.

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The complete question is -

What do you call the one variable that is changed in an experiment?

A. experimental variable

B. controlled variable

C. independent variable

D. dependent variable​

Something done to test a hypothesis that produces new observations is called an experiment.

If you want to test a hypothesis, you need to do an experiment. This is where you take your idea and test it out in the real world. By doing this, you can see what happens and gather new observations.

Experiments are a key part of the scientific process. They help us to understand how the world works and can prove or disprove hypotheses. Without experiments, we would be stuck in our own heads, never knowing for sure if our ideas were correct.

So, if you have a hypothesis that you want to test, get out there and do an experiment! See what happens and learn something new.

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Answer:

The second one

Explanation:

It the graph is correct, it has the most nuetrons