in 400 bce, the greek philosopher democritus first proposed the idea that all matter was composed of atoms. since that time, scientists have learned that, far from resembling tiny marbles, atoms actually have very complex structures. since it has been changed so many times, why is it referred to as the atomic theory rather than the atomic hypothesis?

Answer:

the state of matter changed

Explanation:

Answer:

A) A precipitate is formed

Explanation:

occurs in aqueous solution when two ions bond together to form an insoluble salt, which is known as the precipitate.

The correct answer is option A) 28%. The volume percentage of ethanol = (volume of ethanol / total volume of solution) x 100Volume percentage of ethanol = (38 mL / 138 mL) x 100Volume percentage of ethanol = 0.2754 x 100Volume percentage of ethanol = 27.54 % ≈ 27.6 %

The volume percentage of ethanol in the solution is 27.6%. The volume percentage is the ratio of the volume of solute to the volume of the solution multiplied by 100. It is denoted by (v/v)% and it is used in chemistry to measure the volume of a solute dissolved in a solution. To find the volume percentage of ethanol in the solution, we first need to calculate the total volume of the solution. The total volume of the solution = volume of ethanol + volume of toluene= 38 mL + 100 mL= 138 mL.

Now, we can calculate the volume percentage of ethanol in the solution. The volume percentage of ethanol = (volume of ethanol / total volume of solution) x 100. The volume percentage of ethanol = (38 mL / 138 mL) x 100. The volume percentage of ethanol = 0.2754 x 100Volume percentage of ethanol = 27.54 % ≈ 27.6 %Therefore, the correct answer is option A) 28%.

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Answer: 35.078 to 3 significant figures

Explanation:

Solving;

34.56 + 42.235 * 0.0123 - 0.001

We solve the multiplication first according to the BODMAS rule.

So,

42.235 * 0.0123 = 0.51949

Doing the addition,

34.56 + 0.51949 - 0.001

This gives;

35.079 - 0.001

And finally the subtraction gives;

= 35.078

The concentrations of the species in the 1.40 M NaCH₃COO solution are (Na⁺) = 1.40 M, (OH⁻) = 0 M, (H₂O⁺) = 0 M, (CH₃COOH⁻) = 0.00502 M, and (CH₃COOH) = 0.00502 M.

To calculate the concentrations of the species in a 1.40 M NaCH₃COO (sodium acetate) solution, we need to consider the dissociation of sodium acetate and the ionization of acetic acid.

The dissociation of sodium acetate (NaCH₃COO) can be represented as follows

NaCH₃COO → Na⁺ + CH₃COO⁻

Since sodium acetate fully dissociates in water, the concentration of Na⁺ will be the same as the initial concentration of sodium acetate: 1.40 M.

The ionization of acetic acid (CH₃COOH) can be represented as follows

CH₃COOH ⇌ H⁺ + CH₃COO⁻

The ionization constant for acetic acid (Ka) is given as 1.8×10⁻⁵

Let's denote the initial concentration of acetic acid as x M. At equilibrium, the concentration of H⁺ and CH₃COO⁻ will also be x M.

Using the ionization constant expression for acetic acid, we can write

Ka = [H⁺][CH₃COO⁻] / [CH₃COOH]

1.8×10⁻⁵ = x * x / (1.40 - x)

Since the value of x is expected to be small compared to 1.40, we can approximate the denominator as 1.40.

1.8×10⁻⁵ = x² / 1.40

Rearranging the equation

x² = 1.8×10⁻⁵ × 1.40

x² = 2.52 × 10⁻⁵

Taking the square root of both sides

x = √(2.52×10⁻⁵)

x ≈ 0.00502 M (rounded to four decimal places)

Now we can calculate the concentrations of the species

(Na⁺) = 1.40 M (same as the initial concentration of sodium acetate)

(OH⁻) = 0 M (since sodium acetate and acetic acid do not provide OH⁻ ions)

(H₂O⁺) = 0 M (water does not provide H⁺ ions)

(CH₃COOH⁻) = 0.00502 M

(CH₃COOH) = 0.00502 M

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☁️ Answer ☁️

Yes.

"In so doing, he became the first scientist to explain the behavior of atoms in terms of the measurement of weight. He also uncovered the fact that atoms couldn't be created or destroyed. Dalton's theory additionally examined the compositions of compounds, explaining that the tiny particles (atoms) in a compound were compound atoms"

Hope it helps.

Have a nice day noona/hyung.

Answer:

Thank youuuuu bestie, you really pulling through

Answer:

yessss

Explanation:

Answer: Ik its too late but the answer is yeast.

Explanation: Sugar is yeasts food. If you mix sugar with yeast, and put it in something such as bread, a bottle with a balloon over it, or etc. It will cause it to rise.

When, unknown acid, HA, having a percent dissociation of 2.16%. If the initial concentration of the acid is 0.084 M. Then, the pH of the solution is approximately 2.74. Option C is correct.

To determine the pH of the solution, we first need to calculate the concentration of H⁺ ions in the solution. The percent dissociation is given as 2.16%, which means that 2.16% of the initial concentration of the acid dissociates into H⁺ ions.

Percent dissociation = (concentration of dissociated acid / initial concentration of acid) × 100

2.16% = (concentration of H⁺ / 0.084 M) × 100

Let's solve for the concentration of H⁺;

2.16/100 = concentration of H⁺ / 0.084

0.0216 = concentration of H⁺ / 0.084

Concentration of H⁺ = 0.0216 × 0.084

Concentration of H⁺ = 0.0018144 M

Now that we have the concentration of H⁺ ions, we can calculate the pH using the formula;

pH = -log10(concentration of H⁺)

pH = -log10(0.0018144)

pH ≈ 2.74

Therefore, the pH of the solution is approximately 2.74.

Hence, C. is the correct option.

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Answer:

"Symbolic representation of a chemical reaction in the form of symbols and formulae"

Answer:

A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and formulas.

Explanation:

Example- Zinc metal reacts with dilute sulphuric acid to form zinc sulphate and hydrogen gas. This equation is written as: Zn+H2SO4→ZnSO4+H2.

The statement that supports the claim that mass is conserved in a chemical reaction is the law of conservation of mass, which states that the total mass of the reactants is equal to the total mass of the products.

According to the law of conservation of mass, which is a fundamental principle in chemistry, mass is conserved in a chemical reaction. This means that the total mass of the substances involved in the reaction remains constant before and after the reaction takes place. In other words, no mass is gained or lost during a chemical reaction. The atoms in the reactants rearrange themselves to form new substances, but the total number of atoms remains the same. Therefore, the mass of the reactants is equal to the mass of the products. This principle has been experimentally verified and is a cornerstone of chemical reactions.


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The molecular formula of the compound, given that the compound made up of N and O contains 30.4% N is N₂O₄

First, we shall obtain the molar mass of the compound. Details below:

The mole of the gas is obtained as follow:

PV = nRT

1 × 0.974 = n × 0.0821 × 273

Divide both sides by 24.0553

n = 0.974 / (0.0821 × 273)

n = 0.043 mole

Thus, the molar mass is obtained as:

Molar mass = mass / mole

Molar mass = 4 / 0.043

Molar mass = 93 g/mol

Next, we shall obtain the empirical formula of the compound. details below:

Divide by their molar mass

N = 30.4 / 14 = 2.171

O = 69.6 / 16 = 4.35

Divide by the smallest

N = 2.171 / 2.171 = 1

O = 4.35 / 2.171 = 2

Thus, the empirical formula is NO₂

Finally, we shall obtain the molecular formula of the compound. This is shown below:

Molecular formula = empirical × n = mass number

[NO₂]n = 150

[14 + (2 × 16)]n = 150

46n = 93

Divide both sides by 46

n = 93 / 46

n = 2

Molecular formula = [NO₂]n

Molecular formula = [NO₂]₂

Molecular formula = N₂O₄

Thus, the molecular formula of the compound is N₂O₄

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Answer:

As we know that

At STP

1 mole of any gas occupies 22.4L  

so

15.7L / 22.4L/mole = 0.7moles Cl2  

0.7moles x 6.022x10^23molecules/mole = 4.22x10^23molecules

hope it helps

Answer:

The gas will fill the entire 25 mL of the container. Hope this helps

Explanation:

Answer:

D [polymers]

Explanation:

The joining of monomers (small molecules) is polymerization.

Balanced half-reactions for the given redox reaction are Reduction: Cr2O72-(aq) + 14 H+(aq) + 6 e- → 2 Cr3+(aq) + 7 H2O(l), Oxidation: Zn(s) → Zn2+(aq) + 2 e-. As the reaction proceeds, Zn is oxidized and Cr2O72- is reduced. It is a redox reaction because it involves both oxidation and reduction.

In the half-reaction of oxidation, zinc atoms donate two electrons to become zinc ions. Therefore, oxidation occurs at the anode, which produces electrons that flow into the external circuit. In the reduction half-reaction, Cr2O72- accepts six electrons and seven hydrogen ions to become Cr3+ and water. Therefore, reduction occurs at the cathode, which consumes the electrons produced by the anode. Therefore, the overall balanced redox reaction is Cr2O72-(aq) + 14 H+(aq) + 3 Zn(s) → 2 Cr3+(aq) + 7 H2O(l) + 3 Zn2+(aq). The reaction can be explained as follows: zinc atoms donate two electrons to each hydrogen ion present in the acidic solution to form hydrogen gas, which causes slow corrosion of the zinc electrode. The dichromate ion acts as the oxidizing agent by accepting electrons from the zinc electrode to form zinc ions.

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Answer:

Option 2 and 4 are correct

Explanation:

The reactants in the attached image have more enthalpy and hence less stability as they are more reactive. Thus, Product is more stable than the reactants.

This is an addition reaction in which two reactants add up to form the product.

Very less activation energy is required as the reactants themselves are unstable, possess high energy and hence are very reactive.

Reactants have more energy than the products.  

Answer:

150,000 Joules

Explanation:

KE= 1/2 *mv^2

1/2 * 120 *50^2

60*2500

150,000 Joules

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The more soluble compounds in water are: (a) Nickel(II) hydroxide over magnesium hydroxide, b) Copper(II) sulfide over lead(II) sulfide, (c) Magnesium fluoride over silver sulfate.

Solubility is the ability of a substance to dissolve in a solvent, such as water. It depends on several factors, including the nature of the solute and the solvent, as well as their respective chemical properties.

(a) Magnesium hydroxide (Mg(OH)2) and nickel(II) hydroxide (Ni(OH)2) are both metal hydroxides. However, nickel(II) hydroxide is more soluble in water than magnesium hydroxide. This is because nickel(II) hydroxide forms a more stable complex with water molecules, resulting in better solvation and higher solubility.

(b) Lead(II) sulfide (PbS) and copper(II) sulfide (CuS) are both metal sulfides. Copper(II) sulfide is more soluble in water than lead(II) sulfide. Copper(II) sulfide has a smaller lattice energy and forms a more stable complex with water, leading to higher solubility compared to lead(II) sulfide.

(c) Silver sulfate (Ag2SO4) and magnesium fluoride (MgF2) are both ionic compounds. However, magnesium fluoride is more soluble in water than silver sulfate. This is due to the higher lattice energy of silver sulfate and the stronger ion-dipole interactions between magnesium fluoride and water molecules, resulting in greater solubility for magnesium fluoride.

The more soluble compounds in water are:

(a) Nickel(II) hydroxide over magnesium hydroxide

(b) Copper(II) sulfide over lead(II) sulfide

(c) Magnesium fluoride over silver sulfate.

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The reaction between 1,3-cyclohexadiene and maleic acid (cis-2-butene-dioic acid) leads to the formation of a Diels-Alder adduct.

The product formed is a bicyclic compound resulting from the cycloaddition reaction between 1,3-cyclohexadiene and maleic acid. The reaction involves the formation of a new six-membered ring fused with the cyclohexene ring of 1,3-cyclohexadiene.

The reaction proceeds via the concerted [4 + 2] cycloaddition mechanism, where the diene (1,3-cyclohexadiene) reacts with the dienophile (maleic acid) to form a new sigma bond and two new pi bonds. The resulting adduct exhibits a fused ring system with a double bond in the newly formed six-membered ring.

The specific arrangement of substituents and stereochemistry in the product can vary depending on the orientation of the reactants and the conditions of the reaction. It is important to consider the regioselectivity and stereochemistry when drawing the complete structure of the product.

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The correct expression relating the rates of consumption of reactants and the rates of formation of products for the given reaction is A[[tex]LaCl_{3}[/tex]] / 2Δt = A[La_{2}(CO_3){3}] / 3Δt = A[[tex]Na_{2}CO_{3}[/tex]] / Δt.

The balanced chemical equation for the reaction is 2LaCl_{3}+ 3[tex]Na_{2}CO_{3}[/tex]→ La_{2}(CO_3){3} + 6NaCl. To determine the expressions relating the rates of consumption of reactants and the rates of formation of products, we can use the stoichiometric coefficients from the balanced equation. According to the stoichiometry of the reaction, for every 2 moles of [tex]LaCl_{3}[/tex]consumed, 1 mole of La_{2}(CO_3){3}is formed. Therefore, the expression relating the rates of consumption of LaCl3 and formation of La_{2}(CO_3){3}is A[LaCl_{3}] / 2Δt = A[[tex]La_{2}(CO_3){3}[/tex]] / Δt. Similarly, for every 3 moles of [tex]Na_{2}CO_{3}[/tex]consumed, 1 mole of La_{2}(CO_3){3} is formed. Therefore, the expression relating the rates of consumption of [tex]Na_{2}CO_{3}[/tex] and formation ofLa_{2}(CO_3){3}is A[] / 3Δt = A[La_{2}(CO_3){3}] / Δt.

From the balanced equation, we can also see that 6 moles of NaCl are formed for every 2 moles of LaCl3 consumed. However, the question does not provide options involving the rate of consumption of NaCl. In conclusion, the correct expression relating the rates of consumption of reactants and the rates of formation of products for the given reaction is A[LaCl_{3}] / 2Δt = A[La_{2}(CO_3){3}] / 3Δt = A[[tex]Na_{2}CO_{3}[/tex]] / Δt.

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Answer:

The correct answer is Choice C.

(Phenol red indicator.)

Explanation:

Phenol red indicator is an organic dye that acts as an acid-base reaction indicator in the pH range of 6.8 to 8.4.

In acidic solutions, the color is purple, and in simple solutions, the color is red.

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Answer:

phenol red indicator

Explanation:

Answer:

Meaning:from the valley town; the settlement in the valley. Sounding like the proper English surname it was derived from, Dalton is all about being smart and trendy with equal parts cool and nerdy. Dalton, which comes from “dael” or “valley,” and “tun,” or “settlement,” may have peaked in the 1990s, but that's okay.

Explanation:

a unit used in expressing the molecular weight of proteins, equivalent to atomic mass unit.

Answer:

A unit used in expressing the molecular weight of proteins, equivalent to atomic mass unit.

Or in simpler terms a unit of measure.

Explanation:

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When light is incident on the ion, wavelengths around 500 nm will be absorbed, and the remaining wavelengths will be transmitted or reflected. This provides insight into the electronic structure of the titanium(III) ion and its interaction with light.

The titanium(III) ion, [Ti(H2O)6]3+ in water, absorbs light that is centred around 500 nm. The colour of light absorbed by the ion can be inferred from the visible spectrum of electromagnetic radiation, which ranges from about 400 to 700 nm. Wavelengths around 400-450 nm appear violet, 450-495 nm blue, 495-570 nm green, 570-590 nm yellow, 590-620 nm orange, and 620-700 nm red. Since the titanium(III) ion absorbs light around 500 nm, we can infer that it absorbs light in the green portion of the visible spectrum. Therefore, the titanium(III) ion appears to be a green color.

The absorption of light by compounds can provide insight into the colour of the compound. When light is incident on a compound, certain wavelengths are absorbed, and the remaining wavelengths are transmitted or reflected. The absorbed wavelengths of light depend on the electronic structure of the compound. In the case of the titanium(III) ion, [Ti(H2O)6]3+, it is observed that light centered around 500 nm is absorbed. This means that the electronic structure of the ion allows it to absorb light in the green portion of the visible spectrum. Since the visible spectrum ranges from approximately 400 to 700 nm, it can be inferred that the titanium(III) ion appears to be green in colour. Therefore, when light is incident on the ion, wavelengths around 500 nm will be absorbed, and the remaining wavelengths will be transmitted or reflected. This provides insight into the electronic structure of the titanium(III) ion and its interaction with light.

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Among the salts listed, ZnCO3 (zinc carbonate) and Ba3(PO4)2 (barium phosphate) are the salts that will be substantially more soluble in acidic solution than in pure water.

In the case of ZnCO3, it is an insoluble salt in pure water due to the carbonate ion's basic nature. Carbonate ions (CO3^2-) react with water molecules to form bicarbonate ions (HCO3-) and hydroxide ions (OH-) in an equilibrium reaction. The presence of an acidic solution would shift this equilibrium toward the reactant side, favoring the formation of CO3^2- ions and increasing the solubility of ZnCO3. Similarly, Ba3(PO4)2, which is barium phosphate, is insoluble in pure water. Phosphate ions (PO4^3-) have a basic nature and tend to form insoluble salts with many cations. In an acidic solution, the excess of hydrogen ions (H+) would react with phosphate ions, forming dihydrogen phosphate ions (H2PO4-) or monohydrogen phosphate ions (HPO4^2-). This reaction reduces the concentration of phosphate ions, decreasing the formation of insoluble Ba3(PO4)2 and enhancing its solubility. On the other hand, ZnS (zinc sulfide), BiI3 (bismuth triiodide), and AgCN (silver cyanide) do not show a significant change in solubility in an acidic solution compared to pure water. Their solubilities are primarily governed by factors such as the lattice energy and the ion-ion interactions within the crystal lattice, which are less influenced by changes in pH.

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Answer:

Scientists study Earth's interior by studying

seismic waves. Seismic waves are waves of energy that travel

through Earth.

Explanation:

An electrochemical cell consists of two half-cells separated by a salt bridge or porous membrane that allows ions to flow freely between the two halves.

One half-cell contains an oxidizing agent, which is responsible for accepting electrons, while the other half-cell contains a reducing agent, which is responsible for donating electrons. In an electrochemical cell, the overall reaction must be balanced so that no charge accumulates in either half-cell. The equation that represents the net cell reaction for the given electrochemical cell is as follows.Co(s) + 2Ag⁺(aq) → Co⁺²(aq) + 2Ag(s)The given electrochemical cell consists of the following half-reactions:Anode: Co(s) → Co²⁺(aq) + 2e⁻Cathode: 2Ag⁺(aq) + 2e⁻ → 2Ag(s)The Co metal oxidizes to Co²⁺ ions at the anode, producing two electrons. The Ag⁺ ions are reduced to Ag metal at the cathode, receiving two electrons. These two half-reactions combine to yield the net cell equation.

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