Different atomic models were proposed to explain the distributions of charged particles in an atom. Two of these models proposed by J.J. Thomason and Ernest Rutherford are discussed below.
Similarities
Both models explain the presence of positively charged and negatively charged particles. Thomson's model indicates that atoms have a spherical shape. Rutherford's model indicates that electrons are revolving around the nucleus, which is a sphere shape. Both models state that positively and negatively charged particles are held together by the electrostatic force of attraction.Differences
Thomason's Plum pudding model describes that atom possess a spherical shape in which positive charges are distributed uniformly. Rutherford's model states that positively charges particles concentrates on the center called the nucleus. Thomason's model does not give any idea about the nucleus and Rutherford's model explains about the nucleus. Thomason's model states that electrons are embedded in positively charged particles. In Rutherford's model electrons are revolving around the nucleus in a circular path called orbits.Hence, we can conclude that the key difference is that, Thomason's model does not give any idea about the nucleus and Rutherford's model explains about the nucleus.
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A hurricane track gives the probability of a hurricane following a specific path. What type of scientific model is this?
Which type of chemical bond involves the sharing of valence electrons between two atoms?
Answer:
Nonpolar Covalent
Which of the following reactions is a neutralization reaction? A. ZnCl2(aq) + CaCrO4(aq) → ZnCrO4(s) + CaCl2(aq) B. HNO3(aq) + LiOH(aq) → H2O(l) + LiNO3(aq) C. 2NaOH(aq) + MgCl2(aq) → Mg(OH)2(s) + 2Na+(aq) + 2Cl−(aq) D. 4Fe(s) + 3O2(g) → 2Fe2O3(s)
A neutralization reaction is a chemical reaction between an acid and a base that results in water and a salt. Option B, HNO3(aq) + LiOH(aq) → H2O(l) + LiNO3(aq), is an example of this as it involves the reaction between an acid (Hydrogen Nitrate) and a base (Lithium Hydroxide) to form water and a salt (Lithium Nitrate).
Explanation:In chemistry, a neutralization reaction is a type of chemical reaction where an acid and a base react to form a salt and water. Looking at the provided options, the reaction B. HNO3(aq) + LiOH(aq) → H2O(l) + LiNO3(aq) is a neutralization reaction. This is because Hydrogen Nitrate (HNO3) is an acid and Lithium Hydroxide (LiOH) is a base. The result of their interaction is water (H2O) and a salt (LiNO3).
A neutralization reaction is characterized by an acid reacting with a base and forming water and a salt, which is what happens in this reaction. Hence, option B depicts a neutralization reaction.
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How many n2o4 molecules are contained in 76.3 g n2o4? the molar mass of n2o4 is 92.02 g/mol?
Answer:[tex]4.98\times 10^{23}[/tex] molecules
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{76.3g}{92.02g/mol}=0.83 moles[/tex]
1 mole of [tex]N_2O_4[/tex] contains =[tex]6.023\times 10^{23}[/tex] molecules
0.83 moles of [tex]N_2O_4[/tex] contains =[tex]\frac{6.023\times 10^{23}}{1}\times 0.83=4.98\times 10^{23}[/tex] molecules
Thus total number of molecules in 76.3 g of [tex]N_2O_4[/tex] is [tex]4.98\times 10^{23}[/tex] molecules
Taking into account the definition of molar mass and Avogadro's number, 4.99×10²³ molecules are contained in 76.3 g of N₂O₄.
Avogadro's NumberAvogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023×10²³ particles per mole. Avogadro's number applies to any substance.
Definition of molar massThe molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.
Moles that contain 76.3 g of N₂O₄Being the molar mass of N₂O₄ is 92.02 g/mol, you can apply the following rule of three: If by definition of molar mass 92.02 grams of the compound are contained in 1 mole, 76.3 grams are contained in how many moles?
[tex]amount of moles=\frac{76.3 gramsx1 mole}{92.02 grams}[/tex]
amount of moles= 0.829 moles
Molecules contauned in 0.829 moles of N₂O₄Then you can apply the following rule of three: If by definition of Avogadro's number, 1 mole of the compound contains 6.023×10²³ molecules, 0.829 moles contains how many molecules?
amount of molecules= (6.023×10²³ molecules× 0.829 moles)÷ 1 mole
amount of molecules= 4.99×10²³ molecules
Finally, 4.99×10²³ molecules are contained in 76.3 g of N₂O₄.
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Which of the following statements is not true regarding physical properties and changes?
A. Physical changes include evaporating, boiling, and dissolving.
B. Physical changes can change compounds into elements.
C. Physical properties can be observed without any change in the substance's identity.
D. A series of physical changes, such as filtration and heating, can be used to separate substances with different physical properties.
Answer: Option (B) is the correct answer.
Explanation:
Physical properties and changes are defined as the property or changes that does not cause any change in the chemical composition of a substance.
For example, cutting a piece of sodium with knife is a physical change.
Whereas boiling point, density, melting point etc are all physical changes.
On the other hand, changes that bring change in chemical composition of a substance are known as chemical changes.
For example, reactivity, toxicity etc are all chemical changes.
Hence, we can conclude that the statement physical changes can change compounds into elements, is not true regarding physical properties and changes.
How did the discoveries of scandium (sc) and germanium (ge) affect mendeleevâs work?
they showed mandeleeves predictions were correct
3. The bonds between hydrogen and oxygen in water differ from the bonds between hydrogen and carbon in carbohydrates. How and why do these bonds differ?
If you are given a 1.0 L (1000mL) of an unknown liquid which has the mass of 500 grams it is most likely which of the above substances? Show work to back up your answer. Distilled water density 1.0 g/cm^3 propane density 0.494 g/cm^3 salt water density 1.025 g/cm^3 liquid gold density 17.31g/cm^3
HELP! I will give brainliest for correct answer
In the important industrial process for producing ammonia (the Haber Process), the overall reaction is:
N2(g) + 3H2(g) → 2NH3(g) + 100.4 kJ
A yield of NH3 of approximately 98% can be obtained at 200°C and 1,000 atmospheres of pressure. What is the ΔH in kJ of heat released per mole of NH3(g) formed?
A.)50.2 kJ
B.)50.2 kJ
C.)4 kJ
D.)4 kJ
You are given 450.0 g of a 0.7500 molal solution of acetone dissolved in water. how many grams of acetone are in this amount of solution?
To find the grams of acetone in the given solution, we can use the formula for molality and calculate the mass of acetone based on the molality, molar mass of acetone, and mass of the solvent.
Explanation:The mass of the solution is given as 450.0 g and the molality is given as 0.7500 molal. To find the grams of acetone in the solution, we can use the formula for molality:
Molality (m) = moles of solute / mass of solvent (in kg)
Since 0.7500 molal corresponds to 0.7500 mol of acetone per 1 kg of water, we can calculate the mass of acetone by multiplying the molality by the molar mass of acetone and the mass of the solvent:
Mass of acetone = 0.7500 molal * (58.08 g/mol) * (0.4500 kg)
Therefore, there are 22.52 grams of acetone in this amount of solution.
What type of graph shows the relationship between two quantities as those quantities are changing?
How is gamma radiation different from other types of electromagnetic radiation
Cu(NO3)2 + Zn (s) → Cu (s) + Zn(NO3)2 is an example of which type of reaction?
Combustion
Decomposition
Single-displacement
Double-displacement
Answer:
Single-displacement
Explanation:
What is the concentration of k+ ions in a 0.045 m k2co3 solution assuming complete dissociation?express the concentration in molarity?
Answer: The concentration of [tex]K^+[/tex] ions in the solution is 0.09 M
Explanation:
We are given:
Concentration of [tex]K_2CO_3[/tex] = 0.045 M
The chemical equation for complete dissociation of potassium carbonate follows:
[tex]K_2CO_3(aq.)\rightarrow 2K^+(aq.)+CO_3^{2-}(aq.)[/tex]
By stoichiometry of the reaction:
1 mole of potassium carbonate produces 2 moles of potassium ions and 1 mole of carbonate ions.
So, the concentration of potassium ions in the given solution = [tex](2\times 0.045M)=0.09M[/tex]
Hence, the concentration of [tex]K^+[/tex] ions in the solution is 0.09 M
The density of a gas is 1.49 g/l at a temperature of 24 âc and a pressure of 0.787 atm . calculate the molar mass of the gas.
The molar mass of the gas is approximately [tex]47.56 \text{ g/mol}[/tex]
To calculate the molar mass of the gas, we can use the Ideal Gas Law, which is given by:
[tex]\[ PV = nRT \][/tex]
where:
- [tex]\( P \)[/tex] is the pressure of the gas,
- [tex]\( V \)[/tex] is the volume of the gas,
- [tex]\( n \)[/tex] is the number of moles of the gas,
- [tex]\( R \)[/tex] is the ideal gas constant, and
- [tex]\( T \)[/tex] is the temperature of the gas in Kelvin.
First, need to convert the temperature from Celsius to Kelvin:
[tex]\[ T(K) = T(\°C) + 273.15 \] \[ T(K) = 24 + 273.15 = 297.15 K \][/tex]
The density [tex]\( \rho \)[/tex] of the gas is given as 1.49 g/L. The density is the mass [tex]\( m \)[/tex] divided by the volume [tex]\( V \)[/tex]:
[tex]\[ \rho = \frac{m}{V} \][/tex]
express the mass in terms of the molar mass [tex]\( M \)[/tex] and the number of moles [tex]\( n \)[/tex]:
[tex]\[ m = M \cdot n \][/tex]
Substituting this into the density equation gives:
[tex]\[ \rho = \frac{M \cdot n}{V} \][/tex]
Now, can rearrange the Ideal Gas Law to solve for [tex]\( n \)[/tex]:
[tex]\[ n = \frac{PV}{RT} \][/tex]
Substituting this expression for [tex]\( n \)[/tex] into the density equation gives:
[tex]\[ \rho = \frac{M \cdot PV}{RTV} \][/tex]
[tex]\[ \rho = \frac{M \cdot P}{RT} \][/tex]
Now, can solve for the molar mass [tex]\( M \)[/tex]:
[tex]\[ M = \frac{\rho RT}{P} \][/tex]
know that the ideal gas constant [tex]\( R \)[/tex] is 0.0821 L·atm/(mol·K), so we can plug in the values:
[tex]\[ M = \frac{1.49 \text{ g/L} \cdot 0.0821 \text{ L\·atm/(mol\·K)} \cdot 297.15 \text{ K}}{0.787 \text{ atm}} \] \[ M = \frac{1.49 \cdot 0.0821 \cdot 297.15}{0.787} \] \[ M = \frac{37.41}{0.787} \] \[ M \approx 47.56 \text{ g/mol} \][/tex]
Therefore, the molar mass of the gas is approximately 47.56 g/mol.
H2O has a Hvap = 40.7 kJ/mol. What is the quantity of heat that is released when 27.9 g of H2O condenses?
Answer:
Quantity of heat released = -63.1 kJ
Explanation:
Given:
Enthalpy of vaporization of water, ΔHvap = 40.7 kJ/mol
Mass of water, m = 27.9 g
To determine:
The amount of heat (Q) released
Explanation:
The reaction is: H2O(g) ↔ H2O(l)
The amount of heat evolved during condensation which involves a phase transition from vapor to liquid is given as:
[tex]Q = n*\-Delta Hvap[/tex]
n = moles of water
Since this is a condensation process: ΔHcond = -ΔHvap
[tex]Q = \frac{27.9 g}{18 g/mol} * -40.7 kJ/mol = -63.1 kJ[/tex]
Which statement correctly describes an electrode in a voltaic cell of copper and hydrogen?
A. Copper atoms become copper ions at the anode because the SRP is more positive.
B. Hydrogen ions become diatomic hydrogen at the cathode because hydrogen is always reduced in a voltaic cell.
C. Copper ions become copper atoms at the cathode because copper is always reduced in a voltaic cell.
D. Diatomic hydrogen becomes hydrogen ions at the anode because the SRP is more negative.
Determine the ka of an acid whose 0.294 m solution has a ph of 2.80. 1.2 x 10-5 8.5 x 10-6 2.7 4.9 x 10-7 5.4 x 10-3
1)
Calculate [H+] from the pH:
pH = log { 1 / [H+] } = - log [H+]
=> [H+] = 10 ^ (-pH)
=> [H+] = 10 ^ (-2.80) = 0.00158
2) Assume the stoichiometry 1:1
=> HA aq ---> H(+) aq+ A(-) aq
=> [A-] = [H+] = 0.00158
[HA] = 0.294 – 0.00158 = 0.29242
3) Calculate Ka
Ka = [H+] *[A-] / [HA] = (0.00158)*(0.00158) / 0.29242 =8.54 * 10^ -6
Answer: 8.5 * 10^ -6
We have that the acid dissociation constant(Ka) is mathematically given as
Ka=8.54e-6
The acid dissociation constant(Ka)Question Parameters:
Generally the equation for the H+ pH value is mathematically
pH = log { 1 / [H+] }
[tex][H+] = 10 ^{-pH}[/tex]
[H+]= 0.00158
Where the stoichiometric ratio is 1:1
HA aq ---> H(+) aq+ A(-) aq
[H+] = 0.00158
[HA] = 0.294 – 0.00158
[HA]= 0.29242
Therefore
[tex]Ka =\frac{ [H+] *[A-]}{ [HA] }\\\\Ka=\frac{ (0.00158)*(0.00158)}{0.29242}[/tex]
Ka=8.54e-6
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The polar portion of a cholesterol molecule, which forms hydrogen bonds with the polar heads of neighboring phospholipids and glycolipids, consists of a
How many bonding electrons are in the lewis structure of carbon monoxide, co?
Answer:
6
Explanation:
The Lewis structure represents the valence electrons at the atoms, which ones are shared and the lone pairs. Carbon is at group 4 at the periodic table, and so has 4 electrons in the valence shell; oxygen is at group 6, and so has 6 electrons at the valence shell.
That compound is an exception of the octet rule. A triple bond is done between the atoms, and so, 3 electrons of carbon are shared and 3 electrons of oxygen are shared. Thus, there are 6 bonding electrons, as shown below in red.
Air contains water in a gaseous form called _____.
Air contains water in a gaseous form called water vapor
based on the nebular Theory, which of these is a step in the formation of a new planetary system?
A) evaporation of water
B) nuclear fission of gases
C) repulsion of gaseous masses
D) change of gases into liquids
Final answer:
The formation of a new planetary system involves the condensation of solid particles, accretion and collision of planetesimals, and the formation of protoplanets.
Explanation:
The formation of a new planetary system according to the nebular theory involves several steps. One important step is the condensation of solid particles from the solar nebula, which leads to the formation of planetesimals. The planetesimals then continue to accrete and collide with each other, gradually growing in size. This process eventually results in the formation of protoplanets, which are still in the process of forming into fully developed planets. Therefore, the correct answer is C) repulsion of gaseous masses.
When sodium chloride reacts with silver nitrate, silver chloride precipitates. what mass of agcl is produced from 75.00 g of agno3?
To calculate the atoms of an element in a given molecule, we need to multiply stoichiometry by the number that is written on the foot of that element. Therefore, the mass of AgCl produced from 75.00 g of AgNO[tex]_3[/tex]. is 63.0g.
What is stoichiometry?Stoichiometry is a part of chemistry that help us in making relationship between reactant and product from quantitative aspects.
The balanced reaction is
NaCl + AgNO[tex]_3[/tex] → NaNO[tex]_3[/tex] + AgCl
Mass of AgNO[tex]_3[/tex]=75.00 g
Molar mass of AgNO[tex]_3[/tex]=169.87 g/mol
Moles of AgNO[tex]_3[/tex]=0.44mol
From 1 mole of AgNO[tex]_3[/tex], 1 mole of AgCl is produced.
So, from 0.44 of AgNO[tex]_3[/tex], 0.44 mole of AgCl is produced.
Mass of AgCl =Molar mass of AgCl ×moles of AgCl
Mass of AgCl =143.32 g/mol ×0.44 mole
Mass of AgCl =143.32 g/mol ×0.44 mole
Mass of AgCl =63.0g
Therefore, the mass of AgCl produced from 75.00 g of AgNO[tex]_3[/tex]. is 63.0g.
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In the reaction n2 + 3h2 ---> 2nh3, how many grams of nh3 are produced if 25.0 g n2 reacts with excess h2? question 10 options:
How many moles are there in a 1.40 kg bottle of water?
Find the no. Of electron involved in the electro deposition of 63.5g of cu from a solution of cuso4
Which pair of elements is most apt to form a molecular compound with each other?
How tall would a stack of 1000 pennies in centimeters
Final answer:
To find the height of a stack of 1000 pennies, multiply the thickness of one penny (1.52mm) by 1000, resulting in a stack 1520mm tall, which is 152 centimeters.
Explanation:
The question concerns how tall a stack of 1000 pennies would be in centimeters. To answer this, we must know the thickness of one penny. If we assume the thickness of a single penny is approximately 1.52mm (0.0598 inches), we can calculate the height of 1000 pennies by multiplying the thickness of one penny by the number of pennies in the stack. Since there are 10 millimeters in 1 centimeter, we'll need to convert millimeters to centimeters.
Here is the calculation:
Thickness of one penny = 1.52mmHeight of 1000 pennies = 1000 x 1.52mm = 1520mmHeight in centimeters = 1520mm / 10 = 152cmA student performs an experiment that produces solid sodium chloride. He uses four different catalysts and lets the reaction run for two minutes, and then removes the sodium chloride product. Which is the best way for him to make a consistent measurement that would show the different amounts of sodium chloride produced?
Answer:
☆☆ Measure the four products separately, but using the same scale each time. option C
Explanation:
He cannot do this without affecting at the same time the evolution of the reaction, and of course by doing it on one sample only he will not be able to compare.
Which analogy can best be likened to the activation energy of a chemical reaction?