What contribution did these scientists make to atomic models of the atom?
a. Dalton
b. Thomson
c. Rutherford
d. Bohr

Answer:

Mass = 595  × 10⁻⁸ g

Explanation:

Given data:

Number of atoms of uranium = 15.0 × 10¹⁵ atoms

Mass of uranium = ?

Solution:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

1 mole of uranium = 6.022 × 10²³  atoms of uranium

1 mole × 15.0 × 10¹⁵ atoms / 6.022 × 10²³  atoms of uranium

2.5  × 10⁻⁸ moles

Mass of uranium:

Mass = number of moles ×  molar mass

Mass = 2.5  × 10⁻⁸ moles  × 238 g/mol

Mass = 595  × 10⁻⁸ g

2 Mg + O₂ → 2 MgO

Explanation:

Metallic magnesium (Mg) will react with gaseous oxygen (O₂) to produce solid magnesium oxide (MgO).

2 Mg + O₂ → 2 MgO

To balance the chemical equation the number of atoms of each element entering the reaction have to be equal to the number of atoms of each element leaving the reaction, in order to conserve the mass.

Learn more about:

balancing chemical equations

https://brainly.com/question/8062886

https://brainly.com/question/2399130

#learnwithBrainly

Answer:

T₂ = 51826.1 K

Explanation:

Given data:

Initial Volume = 2.3 L

Final volume = 400 L

Initial temperature = 25 °C (25+ 273 = 298 K)

Final temperature = ?

Solution:

V₁/T₁ = V₂/T₂

T₂ = V₂ T₁/V₁

T₂ =  400 L . 298 K / 2.3 L

T₂ = 119200 K. L / 2.3 L

T₂ = 51826.1 K

To find the temperature in Kelvin for a balloon to expand, we can use Charles's Law. Converting the initial temperature of 25 degrees Celsius to Kelvin gives us 298 K. By setting up the equation, we find that the balloon needs to be heated to approximately 5172.17 K.

To find the temperature in Kelvin at which a 2.3 L balloon expands to a volume of 400 L, we can use Charles's Law. Converting the initial temperature of 25 degrees Celsius to Kelvin gives us 298 K. Setting up the equation, we have:

V₁ / T₁ = V₂ / T₂

Substituting the given values, we have:

2.3 L / 298 K = 400 L / T₂

Cross multiplying and solving for T₂, we find:

T₂ = (400 L * 298 K) / 2.3 L = 5172.1739 K

Therefore, the balloon will need to be heated to approximately 5172.17 K in order to expand to a volume of 400 L.

https://brainly.com/question/30397129

#SPJ3

Answer:

central vacuole

Explanation:

Answer:

C

Explanation:

acids are corrosive since they tend to destroy every single thing they do get a big example is the acidic rain which tends to corrode iron sheet thus making them to appear worn out and full of rust

Answer:

It's C.

Explanation:

c:  eat away at other materials.

Answer:

See every answer with its explanation below

Explanation:

1. Write the molecular equation

         ↑                       ↑                               ↑                                   ↑

     solid nickel     aqueous nitric        aqueous nickel(III)     hydrogen gas

                             acid                         nitrate

2. Balance the molecular equation:

3. Type of reaction

This is a replacement reaction because the nickle is taking the place of hydrogen in the nitric acid and the hydrogen is released. It is also a redox reaction because nickel is being oxidized and hydrogen is being reduced.

The balanced half-reactions are:

         2Ni⁰ → 2Ni³⁺ + 2×(3e⁻)    

         Each nickle atom loses 3 electrons increasing its oxidation state from 0 to +3.

         6H⁺ + 6e⁻ → 3H₂⁰

         Each H⁺ gains 1 electron reducing its oxidation state from +1 to 0.

Answer:

Explanation:

1. Amount of heat absorbed by the water

Where:

2. Standard heat of formation of compound X: ΔHf

Reaction:

From tables (at 25ºC):

- 2,450 kJ/mol = 4 (-393.5 kJ/mol) + 3 (-393.5 kJ/mol) - ΔHf C₄H₆

ΔHf C₄H₆ = 2,450 kJ/mol - 2,754.5 = 304.5 kJ/mol ≈ 305 kJ/mol

Answer:

8.86 g

Explanation:

Molar mass gold = 196.97 g/mol

196.97 g/mol * 0.0450  mol ≈ 8.86 g

The mass of gold that participated in the chemical reaction is 8.86 g.

Molar mass gold = 196.97 g/mol

196.97 g/mol * 0.0450  mol ≈ 8.86 g

A chemical reaction occurs when one or more chemicals are converted to one or more other chemicals. Example: Iron and oxygen combine to form rust. Vinegar and baking soda combine to form sodium acetate, carbon dioxide, and water.

A chemical reaction is a process in which one or more substances are present. H. Convert the reactants to one or more other substances d. H. The products are converted to each other to form new substances with properties different from the molecules of the reactants. This is called the product.

Learn more about chemical reactions. here: https://brainly.com/question/16416932

#SPJ2

Answer: Its already balanced.

Explanation:

Answer:

False

Explanation:

It is true that new crust is being created at the mid-oceanic ridges, but this does not make the Earth any bigger despite the the growth of oceanic crusts in these regions.

The reason that Earth does not get bigger is because the same plates that are being created at the divergent plate boundaries are recycled into the mantle at the subduction zones. Because of this, the surface area of the Earth remains the same.

Answer:

the sodium nitrate in this investigation is

a) the solute

b) undergoing chemical change

generally, solute is the substance which is added in solvent.

The substance which is taken in relatively more volume is the solvent.

so, here sodium nitrate (NaNO₃) is the solute which is dissolved in water (H₂O) , which is solvent.

The reaction between them is :

NaNO₃ + H₂O ⇒ Na⁺ (aq) + NO₃⁻ (aq) ;     (aq) denotes aqueous;

so, here sodium nitrate undergoes chemical change into aqueous sodium ions(Na⁺) and aqueous nitrate ions(NO₃⁻).

Answer:

Explanation:

The law of conservation of mass, as other physic's laws, is universal, meaning that it is obeyed in any circumstance, place, and time.

Thus, any explanation that asserts that the law of conservation of mass is not obeyed must be discarded.

Hence, first, second and fourth options are incorrect.

The law of conservation of mass states that during any physical or chemical process the mass of the substances can neither created nor destroyed; then, what happened that made the mass of the mixture of ingredients mixed by Maria (1053 g) were greater than the mass of the cookies baked for 15 minutes (845 g)?

One of the physical process that occurs when cooking, due to the increase of temperature, is the evaporation of water (besides the chemical reactions between the ingredients, some of which produce other gases).

The water in form of vapor (steam) will "escape" from the mass and the oven, so when the cookies are weighted they will weight less than the mixture, because the water was transformed from liquid state to gas state; i.e. some of the mass evaporated while the cookies were baking. Thus, the third choice is correct.

Answer:

2Ag + Cu(NO3)2

Explanation:

A chemical reaction is represented by a chemical equation which show the reactant and products. Reactants are written on left side of arrow while products are written on right side. The number of atoms are remain same however arrangement of atoms is different on both side.

For example:

Cu(s) + 2AgNO3(aq) →   2Ag + Cu(NO3)2

In this reaction Cu and AgNO3 are reactants while Ag and Cu(NO3)2 are products.The number of atoms are same on both side however arrangement of atoms is different.

Answer:

5.54 × 10¹⁷ atoms

Explanation:

Given data:

Mass of sand = 55.2 μg (55.2 ×10⁻⁶ g)

Molar mass of sand = 60 g/mol

Number of atoms = ?

Solution:

Number of moles = mass/ molar mass

Number of moles = 55.2 ×10⁻⁶ g / 60 g/mol

Number of moles = 0.92 × 10⁻⁶ mol

Number of atoms:

one mole = 6.022 × 10²³ atoms

0.92 × 10⁻⁶ mol ×  6.022 × 10²³ atoms / 1mol

5.54 × 10¹⁷ atoms

Answer:

3) 2000 times the mass of an electron and a unit positive charge

Explanation:

The  proton is approximately 2000 times massive than electron.

Neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.

Symbol of proton= P+  

Symbol of neutron= n0  

Mass of proton=1.672623×10-27 Kg

Mass of neutron=1.674929×10-27 Kg

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.

Symbol= e-

Mass= 9.10938356×10-31 Kg

It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.

Answer:

The answer is 0.01 M

Explanation:

The problem is solved by applying the expression for ionic product of water as follows:

Kw = [H₃O⁺] [OH⁻]

Where Kw is the ionic product of water and it is 1.10⁻¹⁴ M at⁴ 25ºC. As [OH⁻]= 1.10⁻¹² M, [H₃O⁺] will be:

[H₃O⁺]= Kw/ [OH⁻]= 1.10⁻¹⁴M/1.10⁻¹²M= 0.01 M

The enthalpy change for the given reaction is -62.1 kJ. By applying Hess's Law, we can calculate the enthalpy of formation (ΔH°f) for HCl(g). Using the given enthalpy values, we find that ΔH°f for HCl(g) is -62 kJ/mol.

The reaction given is:

SO2Cl2(g) + 2 H2O(ℓ) → H2SO4(ℓ) + 2 HCl(g)

We know that the enthalpy change, ΔH°, for the reaction is -62.1 kJ. We can use the given enthalpy of formation (ΔH°f) values to calculate the enthalpy of formation of HCl(g).

By applying the Hess's Law, we can determine the enthalpy changes based on the given data.

ΔH°f HCl(g) = ΔH°f SO2Cl2(g) + ΔH°f H2SO4(ℓ) - 2ΔH°f H2O(ℓ)

Substituting the given values, we have: ΔH°f HCl(g) = -364 kJ/mol + (-814 kJ/mol) - 2(-286 kJ/mol) = -62 kJ/mol

Therefore, the value of ΔH°f for HCl(g) is -62 kJ/mol.

https://brainly.com/question/14563374

#SPJ12

The heat of formation, or ΔH°f, for hydrogen chloride (HCl(g)) is −92.3 kJ/mol. This was found using Hess's Law and the given standard heats of formation.

The question is asking us to determine the heat of formation, or ΔH°f, for hydrogen chloride (HCl(g)) using the provided standard heats of formation and the heat of the reaction. This falls under the topic of thermodynamics in chemistry.

According to Hess's Law, the total enthalpy change for a reaction is the sum of the enthalpy changes for each step, regardless of the number of steps. So, the ΔH° for the reaction is the sum of the heats of formation of the products minus the sum of the heats of formation of the reactants. Mathematically, that's ΔH° = [ΔH°f(H2SO4) + 2*ΔH°f(HCl)] - [ΔH°f(SO2Cl2) + 2*ΔH°f(H2O)].

The only unknown in this equation is ΔH°f(HCl), which we can solve for:

ΔH°f(HCl) = {[ΔH° + ΔH°f(SO2Cl2) + 2*ΔH°f(H2O)] - ΔH°f(H2SO4)} / 2. Substituting the given values into this equation gives ΔH°f(HCl) = {-62.1 kJ + (-364 kJ) + 2*(-286 kJ) - (-814 kJ)} / 2 = −92.3 kJ/mol. So, the heat of formation for HCl(g) is −92.3 kJ/mol.

https://brainly.com/question/30393610

#SPJ11

Answer:

I. Reagents:

P₄= 123.88 g

H₂ = 12 g

Products:

PH₃= 135.88g

II. Total reagents = 135.88 g

Total products = 135.88 g

III. The principle of conservation of mass

Explanation:

I. First, the molar masses of all reagents and all reaction products are calculated:

• mP₄ = 4 x mP = 4 x 30.97g = 123.88 g / mol

• mH₂ = 2 x mH = 2 x 1.00g = 2 g / mol

• mPH₃ = 4 x mH + m P = 3 x 1.00g + 30.97g = 33.97 g / mol

Having the equation balanced, it can be seen that in order for one mole to react completely of P₄, 6 moles of H₂ must react, and 4 moles of PH₃ will be produced. With the molar masses, we obtain the reacting masses of each reagent and the mass of product that is formed:

Reagents:

P₄: 1 mol ≡ 123.88 g

H₂: 6 moles ≡ 12 g

Products:

PH₃: 4 moles ≡135.88g

II. We add the total mass of the reagents:

Total reagents = mP₄ + mH₂ = 123.88 g + 12 g = 135.88 g

As the reaction product is only PH₃, the total mass of products is 135.88 g

III. It is seen that the mass of reagents necessary to produce the reaction is equal to the mass of product obtained. Therefore, the principle illustrated with this example is the principle of conservation of mass, it says that “In an isolated system, during any ordinary chemical reaction, the total mass in the system remains constant, that is, the mass Consumption of reagents is equal to the mass of the products obtained ”

The mass of reactants (P4 and H2) and product (PH3) is calculated using their molar masses. The reactants have a total mass of 136 g and the product also has a total mass of 136 g, illustrating the law of conservation of mass.

The chemical equation given is P4(s) + 6 H2(g) → 4 PH3(g). This equation tells us that one mole of P4 reacts with 6 moles of H2 to produce 4 moles of PH3.

Firstly, we need to find the molar masses of P4, H2, and PH3. Using the atomic mass of Phosphorus (P) = 31 g/mol and Hydrogen (H) = 1 g/mol, the molar mass of P4 would be 4*31 = 124 g/mol. The molar mass of H2 = 2*1 = 2 g/mol. And the molar mass of PH3 = 31 + 1*3 = 34 g/mol.

Then we can find the total mass of reactants and products: For reactants, one mole of P4 is 124 g and six moles of H2 is 6*2 = 12 g. So, the total mass of reactants is 124+12 = 136 g. For products, four moles of PH3 would be 4*34 = 136 g.

This example illustrates the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. Thus, the total mass of the reactants is equal to the total mass of the products.

https://brainly.com/question/9391940

#SPJ12

Answer:

Zn(s) → Zn⁺²(aq) + 2e⁻

Explanation:

Let us consider the complete redox reaction:

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)

This is a redox reaction because, both oxidation and reduction is simultaneously taking place.

Here Zn(s) is undergoing oxidation from OS 0 to +2

And H in HCl (aq) is undergoing reduction from OS +1 to 0.

Therefore, for this reaction;

Oxidation Half equation is:

Zn(s) → Zn⁺²(aq) + 2e⁻

Reduction Half equation is:

2H⁺ + 2e⁻ → H₂(g)

Final answer:

The correct oxidation half-reaction for the reaction of zinc with hydrochloric acid is Zn(s) → [tex]Zn^2^+(aq) + 2e^-[/tex] Zinc is oxidized by losing two electrons to form zinc ions.

Explanation:

The oxidation half-reaction in the chemical reaction involving zinc and hydrochloric acid is represented by the equation:

Zn(s) → [tex]Zn^2^+(aq) + 2e^-[/tex]

This equation indicates that zinc metal (Zn) is losing two electrons, thus being oxidized to zinc ions ([tex]Zn^2^+[/tex]), which go into solution. The loss of electrons is shown by the electrons being products in this half-reaction. The correct choice for the oxidation half-reaction in the provided list is Zn(s) → [tex]Zn^2^+(aq) + 2e^-[/tex].

Answer:

the answer is c

Explanation:

Answer:

C

Explanation:

The bowling ball has energy in order to to move and hits the pins causing them to scatter (motion)

Final answer:

The pressure of a gas can increase by adding more gas molecules, compressing the gas into a smaller volume, or raising the temperature, all of which lead to more forceful and frequent collisions between the molecules and the container walls.

Explanation:

The pressure of a gas can increase for several reasons. One primary factor is the addition of more gas molecules to a container while its volume remains constant. This increase in the number of molecules results in more frequent collisions with the container walls, thereby increasing the pressure. Similarly, when a gas is compressed into a smaller volume without changing the number of molecules, the pressure increase is due to the rise in the frequency of molecular collisions.

Another way the pressure of a gas can increase is through a rise in temperature. When the gas molecules are heated, they move faster and collide more vigorously with the container walls. This more forceful impact also increases the pressure within the container. Therefore, an increase in temperature or a decrease in volume, or an increase in the number of molecules can all lead to higher gas pressure.

Answer: seas

Explanation:

The ancient astronomers thought the mares on the moon were seas.

Answer:

Seas!

Explanation:

My teacher told me lol

1:electron pair geometry->trigonal pyramid

2: molecular pair geometry->linear

According to molecular geometry, the electron pair geometry is trigonal pyramid and molecular pair geometry is linear.

Molecular geometry can be defined as a three -dimensional arrangement of atoms which constitute the molecule.It includes parameters like bond length,bond angle and torsional angles.

It influences many properties of molecules like reactivity,polarity color,magnetism .The molecular geometry can be determined by various spectroscopic methods and diffraction methods , some of which are infrared,microwave and Raman spectroscopy.

Learn more about molecular geometry,here:

https://brainly.com/question/31323866

#SPJ6

Answer:

answer is b

Explanation:

when you boil water steam come from the pan

Answer:

the answer is D

Explanation:

the reason how ik this is that i already did this test so yea

The example of an exothermic reaction among the provided options is D, where a firework explodes and releases both heat and light, a hallmark of exothermic processes.

An exothermic chemical reaction is a process that releases energy in the form of heat or light. When chemical bonds are formed in a new substance, energy is generally released, indicating an exothermic process. Among the options given, option D, where a firework explodes in the sky and releases heat and light, is a classic example of an exothermic reaction. This option perfectly illustrates the concept as fireworks, upon detonation, release energy in the form of heat and light due to the combustion reactions occurring within them. This reaction releases energy in the form of heat and light, making it an exothermic reaction. Exothermic reactions involve the release of energy, while endothermic reactions involve the absorption of energy.

The ability to be crushed is a physical property and therefore is the answer.

Answer:

the ability to be crushed

Explanation:

Chemical change are effects that is accompanied by changes in the chemical composition of a substance. When chemical changes occur the new substance are chemically different from the formal substance. A new chemical matter is usually formed after the change occur . Example of chemical changes are rusting of iron, toxicity, combustion(substance burning in the presence of oxygen), ability of substance to react with oxygen.

Physical changes are changes that does not alter the chemical composition of the new substance . Example of physical changes are steam condensing into liquid, sugar dissolving in water and crushing a solid substance. The changes are usually physical changes. The overall substance does not change in chemical composition.  

Answer:

The phenomenon of marble cancer is due to (d) acid rain.

Explanation:

The marble cancer is the corrosion of the buildings and statues made up of marble due to the action of sulphuric acid and nitric acid.

[tex]SO_{2}[/tex] and [tex]NO_{x}[/tex] are produced due to pollution.

When these oxides mix with the rain drops in the cloud, they form sulphuric acid and nitric acid. When these acids come in contact with the marble, they cause corrosion.

Hence, acid rain causes the phenomenon of marble cancer.

Answer:

Pb(NO3)2 + K2CO3 ----> PbCO3 + 2KNO3

The answer is B. 2

Hope this helps!

Final answer:

An unsaturated hydrocarbon is a hydrocarbon with one or more double or triple bonds in its carbon chain, as opposed to saturated hydrocarbons with only single bonds. Examples include alkenes and alkynes, as well as unsaturated fatty acids like Oleic acid.

Explanation:

An unsaturated hydrocarbon is a hydrocarbon that contains at least one carbon-to-carbon double bond (C=C) or triple bond (C≡C), which is less than the maximum number of hydrogen atoms possible on its carbon chain. These bonds change the geometry and properties of the molecule compared to saturated hydrocarbons, which only have single bonds. The presence of these multiple bonds characterizes alkenes, which have one or more double bonds, and alkynes, which have one or more triple bonds.

For example, Oleic acid is a type of unsaturated fatty acid that is a long-chain hydrocarbon with at least one double bond along its chain. This kind of fatty acid is found in various foods and is a part of dietary fats and oils. When comparing saturated and unsaturated fats, the unsaturated fats contain these double or triple bonds in their structure.

Answer:

(1) C C3H7OH = 9.200 M

(2) C C3H7OH = 11.647 m

Explanation:

mixture:

∴ 70% = (g C3H7OH/g mix)×100

∴ 30% = (gH2O/g mix)×100

∴ δ mix = 0.79 g/mL

assuming:

⇒ V mix = (100g)×(mL/0.79g) = 126.582 mL mix = 0.1266 L mix

⇒ g C3H7OH = 70g

⇒ g H2O = 30g

∴ Mw C3H7OH = 60.1 g/mol

∴ Mw H2O = 18 g/mol

(1) Molar concentration (M):

⇒ C C3H7OH = ((70 g)(mol/60.1 g))/(0.1266L) = 9.200 M

(2) molal concentration (m):

⇒ C C3H7OH = ((70 g)(mol/60.1g))/(0.100 Kg) = 11.647 m