what is the modification of the Dalton's atomic theory​

Answer:

0.623 M

Explanation:

Step 1: Given data

Step 2: Calculate the percent by volume (%m/v)

We will use the following expression.

[tex]\%m/v = \%m/m \times \rho = 7.00\% \times 1.071g/mL = 7.50g\%mL[/tex]

Step 3: Calculate the molarity

7.50 g of magnesium sulfate are dissolved in 100 mL of the solution. The molarity is:

[tex]M = \frac{7.50g}{120.37g/mol \times 0.100L } = 0.623 M[/tex]

Answer:

d

Explanation:

Answer:

Explanation:

a. change of colour:

A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products. The products have different molecular structures than the reactants. Different atoms and molecules radiate different colours of light. Hence, there usually is a change in colour during a chemical reaction.

Eg: copper reactions with the elements

b. Evolution of gas:

A gas evolution reaction is a chemical reaction in which one of the end products is a gas such as oxygen or carbon dioxide.

Eg: ammonium hydroxide breaks down to water and ammonia gas.

c. Change of smell :

Production of an Odor Some chemical changes produce new smells.  ... The formation of gas bubbles is another indicator that a chemical change may have occured.

Eg: The chemical change that occurs when an egg is rotting produces the smell of sulfur.

d. Change of state:

A chemical reaction is a process in which one or more substances, also called reactants, are converted to one or more different substances, known as products.

Eg: candle wax (solid) melts initially to produce molten wax (liquid)

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Answer:

[tex]Pb(CO_{3})_{2} \\Pb(NO_{3})_{4} \\FeCO_{3}\\Fe(NO_{3})_{2}[/tex]

Explanation:

[tex]Pb^{4+}(CO_{3}^{2-})_{2} --->Pb(CO_{3})_{2} \\Pb^{4+} (NO_{3}^{-})_{4} --->Pb(NO_{3})_{4} \\Fe^{2+} CO_{3}^{2-} --->FeCO_{3}\\Fe^{2+} (NO_{3}^{-})_{2}--->Fe(NO_{3})_{2}[/tex]

Answer: B. 430 K

Explanation:

According to Gibb's equation:

[tex]\Delta G=\Delta H-T\Delta S[/tex]

[tex]\Delta G[/tex] = Gibbs free energy  

[tex]\Delta H[/tex] = enthalpy change  = +62.4 kJ/mol

[tex]\Delta S[/tex] = entropy change  = +0.145 kJ/molK

T = temperature in Kelvin

[tex]\Delta G[/tex]  = +ve, reaction is non spontaneous

[tex]\Delta G[/tex]  = -ve, reaction is spontaneous

[tex]\Delta G[/tex]  = 0, reaction is in equilibrium

[tex]\Delta H-T\Delta S=0[/tex] for reaction to be spontaneous

[tex]T=\frac{\Delta H}{\Delta S}[/tex]

[tex]T=\frac{62.4kJ/mol}{0.145kJ/molK}=430K[/tex]

Thus the Reaction is spontaneous when temperature is 430 K.

Answer:

430 K

Explanation:

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Answer:

200g

Explanation:

n = CV

n = mass/molar mass

mass/molar mass = CV

mass/40 = 2 x 2.5

mass/40 = 5

mass = 5x 40

mass = 200g

Answer:

677.7 mmHg

Explanation:

The first empirical study on the behaviour of a mixture of gases was carried out by John Dalton. He established the effects of mixing gases at different pressures in the same vessel.

Dalton's law states that,the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the individual gases present in the mixture of gases. When a gas is collected over water, the gas also contains some water vapour. The partial pressure of the gas will now be given as; total pressure of gas mixture - saturated vapour pressure of water (SVP) at that temperature.

Given that;

Total pressure of gas mixture = 692.2 mmHg

SVP of water at 17°C = 14.5 mmHg

Therefore, partial pressure of oxygen = 692.2-14.5

Partial pressure of oxygen = 677.7 mmHg

Answer:

Molarity

Explanation:

The conversion of g/mol to g/L molarity can be used. Thus, option C is correct.

The g/mol has been the amount of solute present in a mole. The g/mol has been the molecular weight of the compound.

The g/L has been the mass of solute present in a L of solution. The g/L has  the unit for density.

Molarity has been the moles of solute present in the liter of solution. It has been given as mol/L.

The product of g/mol and g/L gives the value of mol/L. Thus, to convert g/mol to g/L molarity can be used. Thus, option C is correct.

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Answer: [H2SO4] = 0.5M;

              [KOH] = 1M

Explanation: Molarity is the solution concentration defined by:

molarity = [tex]\frac{mol}{L}[/tex] or M

To determine the concentration of the mixture, find how many mols of each compound there are in the mixture:

50 mL = 0.05L

H2SO4

1 mol/L * 0.05L = 0.05mol

KOH

2mol/L * 0.05L = 0.1 mol

The mixture has a total volume of:

V = 50 + 50 = 100 mL = 0.1 L

The concentration of the resullting solutes:

[H2SO4] = [tex]\frac{0.05}{0.1}[/tex] = 0.5 M

[KOH] = [tex]\frac{0.1}{0.1}[/tex] = 1 M

Concentration of H2SO4 is 0.5M while for KOH is 1M.

Answer: The [tex][OH^-][/tex] of a solution is [tex]10^{-12}[/tex] M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]

where,

n = moles of solute

[tex]V_s[/tex] = volume of solution in ml

moles of [tex]HCl[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{0.0912g}{36.5g/mol}=0.0025mol[/tex]

Now put all the given values in the formula of molality, we get

[tex]Molarity=\frac{0.0025\times 1000}{250}=0.01[/tex]

pH or pOH is the measure of acidity or alkalinity of a solution.

[tex]HCl\rightarrow H^++Cl^{-}[/tex]

According to stoichiometry,

1 mole of [tex]HCl[/tex] gives 1 mole of [tex]H^+[/tex]

Thus [tex]0.01[/tex] moles of [tex]HCl[/tex] gives =[tex]\frac{1}{1}\times 0.01=0.01[/tex] moles of [tex]H^+[/tex]

Putting in the values:

[tex][H^+][OH^-]=10^{-14}[/tex]

[tex][0.01][OH^-]=10^{-14}[/tex]

[tex][OH^-]=10^{-12}[/tex]

Thus the [tex][OH^-][/tex] of a solution prepared by dissolving 0.0912 g of hydrogen chloride in sufficient pure water to prepare 250.0 ml of solution is [tex]10^{-12}[/tex] M

The  [OH-] of a solution is [tex]10^{12}[/tex] M.

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

M = n/ V..................(1)

where,

n = moles of solute

V = volume of solution in ml

Calculation for number of moles:

Moles of HCl =  0.0912 g/ 36.5 g/mol = 0.0025 mol

On substituting the values in equation 1:

M = n/ V

M= 0.0025*1000 / 250

M=0.01 M

pH or pOH is the measure of acidity or alkalinity of a solution.

[tex]HCl---- > H^++Cl^-[/tex]

According to stoichiometry,

1 mole of HCl  gives 1 mole of [tex]H^+[/tex]

Thus, 0.01 moles of HCl gives =  1 / 1 *0.01 = 0.01 mole of [tex]H^+[/tex]

On adding the values:

[tex][H^+][OH^-]=10^{14}\\\\(0.01)[OH^-]=10^{-14}\\\\OH^-=10^{-12}[/tex]

Thus, the [OH-]  of a solution prepared by dissolving 0.0912 g of hydrogen chloride in sufficient pure water to prepare 250.0 ml of solution is [tex]10^{-12}[/tex]  M.

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Answer:

33.3% of Sn in the sample

Explanation:

The addition of SO₄⁻ ions produce the selective precipitation of Pb²⁺ to produce PbSO₄.

Moles of PbSO₄ (molar mass 303.26g/mol) in 2.93g are:

2.93g ₓ (1mol / 303.26) = 9.66x10⁻³ moles PbSO₄ = Moles Pb²⁺.

As molar mass of Pb is 207.2g/mol, mass in 9.66x10⁻³ moles of Pb²⁺ is:

9.66x10⁻³ moles of Pb²⁺ ₓ (207.2g / mol) = 2.00g of Pb²⁺

As mass of the sample is 3.00g, mass of Sn²⁺ is 3.00g - 2.00g = 1.00g

And the percentage of Sn in the sample is:

1.00g / 3.00g ₓ 100 =

Answer:

I would put A

Explanation:

A new substance is produced as a result of a chemical reaction in which bonds between the molecules of the reactant and product are broken and new bonds are formed. Here the products are Al₂O₃ and Fe. The correct option is A.

Chemical reactions are interactions between two or more molecules that result in the production of new products. Products, as opposed to reactants, are compounds that result from an interaction between two other substances.

The reactants are on the left, while the products that are created are on the right. A one-headed or two-headed arrow connects the reactants and products.

Thus the correct option is A.

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Answer:

3 RbOH + H₃PO₄ → Rb₃PO₄ + 3 H₂O

Explanation:

Let's consider the double-replacement reaction between rubidium hydroxide and phosphoric acid to form rubidium phosphate and water. The cation rubidium replaces the cation hydrogen and the anion hydroxyl replaces the anion phosphate. The balanced chemical reaction is:

3 RbOH + H₃PO₄ → Rb₃PO₄ + 3 H₂O

Answer:

Explanation:

Volume of silver cube = 2.42³ = 14.17 cm³

mass of silver cube = volume x density

= 14.17 x 10.49 = 148.64 gm

Volume of gold cube = 2.75³ = 20.8  cm³

mass of gold cube =  20.8 x 19.3 = 401.44 gm

specific heat of silver and gold are .24 and .129 J /g°C

mass of 112 mL water = 112 g

Heat absorbed = heat lost = mass x specific heat x temperature fall or rise

Heat lost by metals

= 148.64 x .24 x ( 85.4 -T) + 401.44 x .129 x ( 85.4 - T )

= (35.67 + 51.78 ) x ( 85.4 - T )

87.45 x ( 85.4 - T )

= 7468.23 - 87.45 T

Heat gained by water

= 112 x 1 x ( T - 20.5 )

= 112 T - 2296

Heat lost = heat gained

7468.23 - 87.45 T = 112 T - 2296

199.45 T = 9764.23

T = 48.95° C

Answer:

[tex]x_{acetone}=7.970x10^{-3}[/tex]

Explanation:

Hello,

In this case, for the given molarity, we can assume a volume of 1 L of solution, to obtain the following moles of acetone:

[tex]n=0.422mol/L*1L=0.422mol[/tex]

Then, with the density of solution, we can compute the mass of the solution for the selected 1-L volume basis:

[tex]m_{solution}=1L*\frac{1000mL}{1L}*\frac{0.970g}{1mL}=970g[/tex]

After that, we compute the mass of water in the solution, considering the mass of acetone (molar mass = 58.08 g/mol):

[tex]m_{H_2O}=970g-0.422molAcetone*\frac{58.08g\ Acetone}{1mol\ Acetone} =945.49gH_2O[/tex]

Next, the moles of water:

[tex]n_{H_2O}=945.49g*\frac{1molH_2O}{18gH_2O} =52.53molH_2O[/tex]

Finally, the mole fraction:

[tex]x_{acetone}=\frac{n_{acetone}}{n_{acetone}+n_{H_2O}}=\frac{0.422mol}{0.422mol+52.53mol}\\ \\x_{acetone}=7.970x10^{-3}[/tex]

Regards.

Combining quantum theory with wave motion of atomic particles is: Wave Mechanics

Answer:

3-bromobenzoic acid

Explanation:

In this case, we have to remember that the [tex]Br_2/FeBr_3[/tex]  is a reaction in which we add Br into the molecule an electrophilic aromatic substitution. Additionally, we have a carboxylic acid in the benzene. This carboxylic acid is an ortho director because is a deactivating group (it removes electrons from the benzene ring). With this in mind, a "Br" atom would be added in an ortho position respect to the COOH group and we will obtain 3-bromobenzoic acid.

See figure 1.

I hope it helps!

To create 3-bromobenzoic acid, a "Br" atom would be placed at an orthogonal position to the COOH group according to electrophilic aromatic substitution.

Electrophilic aromatic substitution is a type of organic reaction in which an atom or group in an aromatic ring is substituted with an electrophile. It is a fundamental reaction in aromatic chemistry that happens due to the aromatic system's high electron density.

It is an electrophilic aromatic substitution process in which Br is incorporated into the molecule. In addition, the benzene contains a carboxylic acid. Because it removes electrons from the benzene ring, this carboxylic acid functions as an ortho director. To create 3-bromobenzoic acid, a "Br" atom would be placed at an orthogonal position to the COOH group. The product is seen in the photographs below.

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Answer:

1.30atm

Explanation:

P1/T1 = P2/T2

1.07/393 = P2/478

Answer: the first one is correct

Explanation:

jhkfjfjgjgjjggj

Answer:

a lower temperature to liquefy

Explanation:

Answer:

A, B and C are compounds

Explanation:

First of all, I need to establish that when carbon is burnt in excess oxygen, carbon dioxide is obtained as shown by this equation; C(s) + O2(g) ----> CO2(g).

Looking at the presentation in the question, A was said to be heated strongly and it decomposed to B and C. Only a compound can decompose when heated. Elements can not decompose on heating. Secondly, compounds usually decompose to give the same compounds that combined to form them. Compounds hardly decompose into their constituent elements.

Again from the information provided, the compound A is a white solid. This is likely to be CaCO3. It decomposes to give another white solid. This may be CaO and the gas was identified as CO2.

Hence;

CaCO3(s)--------> CaO(s) + CO2(g)

Answer:

E) Al³⁺

Explanation:

A reaction involving a gain of electrons is known as a reduction reaction because the oxidation number of the species gaining the electron is reduced.

In the given question, the oxidation number (charge) of particle accepting two electrons will decrease by 2. From the given options;

A. K is a neutral atom with oxidation number of 0. If is accepts two electrons, its oxidation number becomes -2.

K + 2e⁻  ----> K⁻²

B) Fe²⁺ has a charge of +2. If it accepts two electrons, its charge comes 0.

Fe⁺ + 2e⁻  ----> Fe

C) O²⁻ has a charge of -2. if it accepts two electrons, it will have a charge of -4.

O²⁻ + 2e⁻  ---->  O⁴⁻

D) Ne has a charge of zero. If it accepts two electrons, its charge becomes -2.

Ne + 2e⁻   ---->   Ne²⁻

E) Al³⁺ has a charge of +3. If it gains two electrons, its charge becomes +1.

Al³⁺ + 2e⁻   ---->   Al⁺

Answer:

"The active site of the enzyme has a complementary rigid structure" belongs to the key and lock system

"The conformation of the enzyme changes when it binds to the substrate so that the active site conforms to the substrate." belongs to the induced fit system.

"The substrate binds to the enzyme at the active site, forming an enzyme-substrate complex" belongs to both, that is, the key and lock system and the induced fit system.

"The substrate binds to the enzyme through non-covalent interactions" can belong to both enzyme systems.

Explanation:

Enzymatic key and lock systems bear this name because the enzyme at its site of union with the substrate has an ideal shape so that its fit is perfect, similar to a headbreaker, so once they are joined they are not It can bind another substrate to the enzyme, since they are generally associated with strong chemical bonds.

The shape of the enzyme's active site is a negative of what the shape of the substrate would be.

On the other hand, in the mechanism or enzyme system of induced adjustment, the enzyme has an active site that is where it binds with the substrate and another site where another chemical component binds, which when this chemical component binds this enzyme changes its morphology and becomes "active" to bond with your substrate.

This happens a lot in the inactive enzymes that are usually activated in digestive processes since the fact that these enzymes are constantly active would be dangerous, therefore the body takes the induced enzyme system as a control mechanism, where a molecule or chemical compound induces change morphological of an enzyme by means of the allosteric union so that it joins its substrate and catalyzes or analyzes it, depending on the enzymatic character of the enzyme.

Answer:

Option D is correct.

n = 6 to n = 2

Explanation:

Like all waves emitted from the movement of electrons from one energy level to another, the wavelength (λ) is given by the equation involving Rydberg's constant

(1/λ) = Rₕ [(1/n₂²) - (1/n₁²)]

where Rₕ = 10973731.57 m⁻¹ = (1.0974 × 10⁷) m⁻¹

n₂ = principal quantum number corresponding to the final energy level of the electron = 2 (For Balmer Series)

n₁ = principal quantum number corresponding to the final energy level of the electron = ?

λ = 410 nm = (410 × 10⁻⁹) m

(1/λ) = (2.439 × 10⁶) m⁻¹

2.439 × 10⁶ = (1.0974 × 10⁷) [(1/2²) - (1/n₁²)]

0.25 - (1/n₁²) = (2.439 × 10⁶) ÷ (1.0974 × 10⁷) = 0.2222602562

(1/n₁²) = 0.25 - 0.2222602562 = 0.0277397438

n₁² = (1/0.0277397438) = 36.05

n₁ = 6

Hope this Helps!!!

Answer:

C. Potential energy

Explanation:

Kinetic energy and gravitational potential energy are both forms of potential energy. Potential energy is stored energy, when an object is not in motion it has stored energy. When an object is an motion it has kinetic energy. An object posses gravitational potential energy when it is above or below the zero height.

Answer:

Wavelength, λ  = 6.7 x 10^-11 m

Explanation:

Frequency and wavelength are inversely proportional to each other.

In this problem;

f =  4.5 x 10^18 Hz

wavelength, λ = ?

Speed of light, c = 3 x 108 m/s.

These variables are related by the following equation;

c = λ * f

Making λ subject of focus, we have;

λ = c / f

λ = 3 x 10^8 / 4.5 x 10^18

λ  = 0.67 x 10^-10

λ  = 6.7 x 10^-11 m

Answer:

Thrust.

Explanation:

hope this helps you :)

Answer:

thrust

Explanation:

Answer:

Exothermic interractive are the following: NaOH, KOH, CaCl₂

Endothermic interactive are the following: NaCl, NH₄NO₃, NaNO₃

Explanation:

NaOH, KOH, and CaCl2 are exothermic reactants. NaCl, NH4NO3, and NaNO3 are endothermic interacting substances.

Chemical processes that can release or absorb energy are referred to as endothermic. In endothermic reactions, more energy is used when bonds in the reactants are broken than is released when new bonds are formed in the products.

When the temperature of the an isolated system drops while the surroundings of the a non-isolated system warm up, this is known as an endothermic response. The heat of reaction is generally positive in endothermic processes (qrxn>0).

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Answer:

d) El agua pesada contiene mas elementos

Explanation:

La diferencia fundamental entre el agua pesada y el agua ligera es que la primera tiene una proporción mayor de deuterio que la segunda. El deuterio es un ión del hidrógeno que tiene un peso atómico mayor que el hidrógeno común y corriente. Por ende, la opción D ofrece la mejor aproximación.

Answer:

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Explanation:ki

Answer:

Metallic bonding

Explanation:

Ionic bonding involves the transfer of electrons from a highly electropositive metal to a highly electronegative nonmetal.

The metallic bond is somewhat similar to the ionic bond since there are also charged positive metal ions. The only difference is that there isn't any electronegative element that accepts the electrons.

In a metallic bond, the positively charged metal ions are bound together by a sea of mobile electrons. The attractive force between the metal ions and the mobile electrons hold the metallic crystal lattice together.