Which of the following is true in regard to ions? A. A cation will hold a positive charge if it gains one or more electrons. B. An ionized atom has a number of protons that is unequal to the number of electrons. C. Ions can carry only positive charges. D. Losing one or more electrons will turn an atom into an anion.

Answer:

The given atom is of Ca.

Explanation:

Given data:

Speed of atom = 1% of speed of light

De-broglie wavelength = 3.31×10⁻³ pm (3.31×10⁻³ / 10¹² = 3.31×10⁻¹⁵ m)

What is element = ?

Solution:

Formula:

m = h/λv

m = mass of particle

h  = planks constant

v = speed of particle

λ = wavelength

Now we will put the values in formula.

m = h/λv

m = 6.63×10⁻³⁴kg. m².s⁻¹/3.31×10⁻¹⁵ m ×( 1/100)×3×10⁸ m/s

m = 6.63×10⁻³⁴kg. m².s⁻¹/ 0.099×10⁻⁷m²/s

m = 66.97×10⁻²⁷ Kg/atom

or

6.69×10⁻²⁶ Kg/atom

Now here we will use the Avogadro number.

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,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

Now in given problem,

6.69×10⁻²⁶ Kg/atom × 6.022 × 10²³ atoms/ mol × 1000 g/ 1kg

40.3×10⁻³×10³g/mol

40.3  g/mol

So the given atom is of Ca.

The movement of sounds, in the same manner, is called wavelength.

The correct element is Ca.

The data in the question is as follows:-

The formula we will used is [tex]m = \frac{h}{λv}[/tex]

The data is given is as follows:-

Now we will put the values in the formula and solve the equation.

[tex]m = \frac{6.63*10^{-34}}{3.31*10^{-15} ( \frac{1}{100})*3*10^8}[/tex]

After solving the value of m is[tex]66.97*10^{-27}[/tex]

Now in the given problem, the solution is as follows:-

[tex]6.69*10^{-26}* 6.022 * 10^{23} * 1000[/tex]

After solving the equation the answer is 40.3

Hence, the 40.3 is the mass of calcium.

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Answer:

54 g is the theoretical yield

Explanation:

This is the reaction:

2H₂ + O₂ → 2H₂O

So 2 moles of hydrogen react with 1 mol of oxygen, to produce 2 mol of water.

If I have 3 moles of H₂ and 2 moles of O₂, the my limiting reactant is the hydrogen.

1 mol of O₂ react with 2 moles of H₂

S 2 mol of O₂ would react with 4 moles (I only have 3 moles)

Then, ratio is 2:2 the same as 1:1

As 2 mol of H₂ produce 2 moles of water, 3 moles of H₂ will produce 3 moles of H₂O.

This is the theoretical yield in moles. Let's convert them to mass (mol . molar mass)

3 mol . 18g/m = 54 g

Answer:

The theoretical yield of the reaction is 54.06 grams

Explanation:

Step 1: Data given

Moles of hydrogen gas = 3.0 moles

Moles of oxygen gas = 2.0 mol

Molar mass of H2O = 18.02 g/mol

Step 2: The balanced equation

2H2 + O2 → 2H2O

Step 3: Calculate the limiting reactant

For 2 moles H2 consumed, we need 1 mol O2 to produce 2 moles of H2O

Hydrogen gas is the limiting reactant. It will be completely consumed. (3.0 moles).

Oxygen gas is in excess. There will react 3.0/2 = 1.5 moles of O2.

There will remain 2.0 -1.5 = 0.5 moles

Step 4: Calculate the moles of H2O

For 2 moles of H2 we'll have 2 moles of H2O

For 3 moles H2 we'll have 3.0 moles of H2O

Step 5: Calculate theoretical yield of H2O

Mass H2O = moles H2O * molar mass H2O

Mass H2O = 3.0 moles * 18.02 g/mol

Mass H2O = 54.06 grams

The theoretical yield of the reaction is 54.06 grams

Answer : The number of moles of ions form are, [tex]3.14\times 10^{23}[/tex] and there are 3 ions formed.

Explanation :

First we have to calculate the moles of calcium iodide.

[tex]\text{Moles of }CaI_2=\frac{\text{ given mass of }CaI_2}{\text{ molar mass of }CaI_2}[/tex]

Molar mass of calcium iodide = 293.9 g/mol

Mass of calcium iodide = 51.0 g

[tex]\text{Moles of }CaI_2=\frac{51.0g}{293.9g/mole}=0.174moles[/tex]

Now we have to calculate the number of moles of ions.

As we know that when calcium iodide dissolved in water then it dissocites to give calcium ion and iodide ion.

The balanced chemical reaction will be:

[tex]CaI_2(aq)\rightarrow Ca^{2+}(aq)+2I^{-}(aq)[/tex]

From this we conclude that there are 3 ions formed.

As, 1 mole of calcium iodide dissociate to give [tex]3\times (6.022\times 10^{23})[/tex] number of ions

So, 0.174 mole of calcium iodide dissociate to give [tex]0.174\times 3\times (6.022\times 10^{23})=3.14\times 10^{23}[/tex] number of ions

Thus, the number of moles of ions form are, [tex]3.14\times 10^{23}[/tex]

Answer : The atomic mass of E is, 30.4 g/mol

Explanation :

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of E = 27.52 g

Mass of S = 72.48 g

First we have to calculate the moles of sulfur.

Moles of S = [tex]\frac{\text{ given mass of S}}{\text{ molar mass of S}}= \frac{72.48g}{32g/mole}=2.265moles[/tex]

Now we have to calculate the moles of E by comparing the stoichiometry of the compound.

The given compound formula is, [tex]E_4S_{10}[/tex]

As, 10 moles of sulfur combine with 4 moles of E

So, 2.265 moles of sulfur combine with [tex]\frac{2.265}{10}\times 4=0.906[/tex] moles of E

Thus, the moles of E is, 0.906 moles.

Now we have to calculate the atomic mass of E.

Atomic mass of E = [tex]\frac{\text{ given mass of E}}{\text{ moles of E}}= \frac{27.52g}{0.906mole}=30.4g/mol[/tex]

Thus, the atomic mass of E is, 30.4 g/mol

Answer:

The sketch and explanation is attached below.

Explanation:

Matter consists of atom, which is the smallest particle of an elements. Atoms consists of three parts; The protons which are positively charged, the neutrons which are neutral and the electrons which are negatively charged. both the proton and neutron make up the nucleus while the electron orbit outside of the nucleus.

Protons ; are positively charged which form the basis of the atoms. the symbol for protons is Z and the number of protons which make up an atom is also known as the atomic number which is a unique property of an element, no two elements must have the same atomic number.

Neutrons ; are neutral in an atom as such they do not have a charge and it is indicated by the letter N. the number of protons is the difference between the mass number and the atomic number of the proton number.

Electrons ; are negatively charged and they orbit outside of the nucleus of an atom. The mass of a proton is 1840 times greater than the mass of an electron.

Various scientist have given their own explanation of the model of an atom, people like Ernest rutherford, Neil bohr, John Dalton, JJ Thompson et al came up with different postulation of the atomic model. Neil bohr for example said about electrons they they do not only have energy, but they have a particular energy which are confined into energy levels that is the energy of the electrons were quantised. John dalton -the English scientist also came about his atomic theory ; each element has its own unique type of atom, atoms of each individual element have the same atomic weight, when atoms combine, they do so in fixed ratios. although most of dalton's theory have been modified.

An electron shell on the other hand comprises of the outer part of an atom i.e outside the nucleus. shells have sub-shells or sublevels. there are K-L-M shells. sodium (Na) for example has an atomic number of 11 and an electronic configuration of 2)8)1 - this implies that it has 3-shells -k-L-M and the last electron in its shells which is 1 is known as the valence electrons or the outermost electron. it is the number of electron at the outermost shell that takes part in the donating and accepting of electron.

Calcium(Ca) for example has an atomic number of 20, electronic configuration 2)8)8)2, K-L-M-N, it has four shells. the outermost electron (2) is the valence electron and it is the electron which determines the group of an element. this explains why sodium (Na) is a group 1 element and calcium (Ca) is a group 2 elements.

The valence electrons is the only electron that takes part in sharing during bonding. for example Sodium chloride(Nacl) - sodium has 1 electron at the outermost shell and chlorine has 7 electron in its outermost shell, hence its needs 1 more electron to attain the octet state , this 1 electron will be donated by Na to become a cation as such sodium becomes the reducing agent and chlorine is the oxidizing agent as it accept electron to become a anion. The essence of bonding or transfer or sharing of electrons is for atoms of element to either attain the octet or duplet state.

The atom model features a nucleus, electrons in shells, and valence electrons influencing bonding. Outer shell electron interactions drive covalent and ionic bonding, crucial in chemical reactivity.

The atom model is based on the understanding that atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in orbitals. The electrons are organized into electron shells, each with a specific energy level. The innermost shell is filled first before moving to the next, and the outermost shell determines the atom's chemical properties.

Electron shells are designated by principal quantum numbers (n), and each shell can accommodate a specific number of electrons. The first shell (n=1) can hold up to 2 electrons, the second (n=2) can hold up to 8, and so on. Electrons in the outermost shell are called valence electrons, and these play a crucial role in chemical bonding.

The number of electrons in the outermost shell influences an atom's reactivity. Atoms strive to achieve a full outer shell, following the octet rule. Some atoms achieve this by sharing electrons (covalent bonding), while others transfer electrons (ionic bonding). In covalent bonding, atoms share electrons to complete their outer shells, forming stable molecules. In ionic bonding, atoms transfer electrons, creating ions with full outer shells.

Understanding electron distribution in shells provides insight into an atom's behavior in chemical reactions, facilitating predictions about its bonding tendencies. This model, incorporating electron shells, enhances our comprehension of atomic structure and guides our understanding of chemical interactions.

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Answer:

Thus the  correct order would be  a, b,d  and then c

Explanation:

Rank of rock-forming minerals from most abundant to least abundant

1. Silicates

2. Carbonates

3. Oxides

4. Sulfates

Thus the  correct order would be  a, b,d  and then c

Answer:

3.2L

Explanation:

PV=nRT

since pressure and temperature are held constant we have V=nR

R is a constant also,

Thus; [tex]\frac{v1}{n1}=\frac{v2}{n2}[/tex]

v1=1.5L  , n1=3mol, n2=1.4mol

[tex]\frac{1.5}{3}=\frac{v2}{1.4}[/tex]

v2=[tex]\frac{1.5}{3}*1.4[/tex]

v2=3.2L

Answer:

65 L is the volume of CO required

Explanation:

This is the reaction:

2CO (g) + O₂ (g) →  2CO₂ (g)

We must work with density to solve this problem

Density = Mass / volume

Let's determine the moles of O₂

1.43 g/mL = mass / 32500 mL

Notice, that we had to convert the volume from L, to mL, because the units of density.

Mass of O₂ → 1.43 g/mL . 32500 mL = 46475 g

Let's convert the mass to moles (mass / molar mas)

46475 g / 32 g/mol = 1452.3 moles

So ratio is 1:2

1 mol of oxygen needs 2 moles of CO, to react

Then, 1452.3 moles of O₂ would need the double of CO to react

1452.3 moles . 2 = 2904.6 moles of CO

This moles are contained in (mol . molar mass) =

2904.6 mol . 28 g/mol =81328.8 g

Density of CO = Mass of CO/ Volume of CO

1.25 g/mL = 81328.8 g / Volume of CO

81328.8 g / 1.25 g/mL  = 65063 mL

If we convert to L

65063 mL = 65.0 L

To react 32.5 liters of oxygen gas with carbon monoxide, the balanced chemical reaction shows a ratio of 2:1 between CO and O₂, thus requiring 65 liters of carbon monoxide.

The volume of carbon monoxide required to react with 32.5 liters of oxygen gas can be determined by looking at the coefficients in the balanced chemical equation of the reaction, which is not provided in the question but assuming a typical reaction between carbon monoxide and oxygen to form carbon dioxide, the equation is:

2 CO(g) + O₂(g) → 2 CO₂(g)

This equation shows that 2 volumes of CO react with 1 volume of O₂. Therefore, to find the volume of CO needed for 32.5 liters of O₂, you multiply the volume of O₂ by 2, because the ratio is 2:1.

The required volume of CO = 32.5 liters of O₂ × 2 (because of the ratio 2:1) = 65 liters of CO.

Answer:

Hi.

The temperature is approximately zero degrees (0°C)

Explanation:

It is important to keep in mind that in the production of ice cream the decrease in the freezing point of the water present in the mixture is called the antifreeze power of the mixture. In ice cream, the freezing point decrease will be caused by each substance that is dissolved in the mixture: lactose, salts, sugars and any other substance. Each of these substances will contribute to the decrease in the freezing point of the mixture. The phase diagram attached in the file shows the sugar solutions in water. When a solution cools (point A), there comes a time when the freezing curve is reached (point B). At that moment ice begins to appear. As shown in the diagram this temperature is approximately zero degrees (0 ° C).

Answer:

The answer to your question is letter a. 65.13%

Explanation:

Percent composition of Copper in Cu(OH)₂

Process

1.- Calculate the molecular weight of Copper hydroxide

Cu(OH)₂ = 64 + (16 x 2) + (2 x 1)

              = 64 + 32 + 2

              = 98 g

2.- Solve the problem using proportions

                       98 g of Cu(OH)₂  ---------------  100 %

                       64 g of Cu           ----------------   x

                           x = (64 x 100) / 98

                           x = 6400 / 98

                           x = 65.2 %

Final answer:

The percent composition of copper in copper (II) hydroxide (Cu(OH)2) is calculated using the molar masses of its elements. The molar mass of Cu(OH)2 is 97.57 g/mol, and the molar mass of copper (Cu) is 63.546 g/mol. The correct answer is 65.13% Cu.

Explanation:

To calculate the percent composition of copper in copper (II) hydroxide (Cu(OH)2), we need to calculate the molar mass of this compound first. The molar mass of Cu(OH)2 is 97.57 g/mol. Using the average atomic mass of copper (63.546 g/mol), we can determine the mass percentage of copper in the compound.

The molar mass of Cu(OH)2 is the sum of the molar masses of one copper atom (63.546 g/mol), two oxygen atoms (2 × 16.00 g/mol), and two hydrogen atoms (2 × 1.01 g/mol):

Molar mass of Cu(OH)2 = 63.546 g/mol (Cu) + 32.00 g/mol (O) + 2.02 g/mol (H) = 97.57 g/mol

Therefore, the percent composition of copper in Cu(OH)2 can be calculated as follows:

% Cu = (molar mass of Cu / molar mass of Cu(OH)2) × 100

% Cu = (63.546 g/mol / 97.57 g/mol) × 100 ≈ 65.13%

Hence, the correct answer is 65.13 % Cu.

Answer:

B) The volume is the same for any gas.

Explanation:

Considering the ideal gas equation as:-

[tex]PV=nRT[/tex]

where,  

P is the pressure

V is the volume

n is the number of moles

T is the temperature  

R is Gas constant having value = 8.314 J/ K mol

At STP,  

Pressure = 1 atm  

Temperature = 273.15 K

So, applying the values we get that 1 mole of any gas occupies a volume of 22.4 L

Thus, correct option is:- B) The volume is the same for any gas.

Answer:MnCO3+2H2O----->MnO2+ HCO3-+2e-+3H+

Explanation:The equation to be balanced is

MnCO3 ------> MnO2+HCO3-

The oxidation number of Mn changes from +2 in MnCO3 to +4 in MnO2

Therefore two electrons must be added to the right as shown below:

MnCO3 -------> MnO2+ HCO3-+ 2e-Now,there is one negative charge HCO3- and 1 negative charge on the two electrons making a total of -3 charges on the right. There is zero charge on the left.

To balance the equation,add3H+on the right,to cancel out the charges.

MnCO3 --------> MnO2+HCO3-+2e-+3H+

Adding H2O to balance Hydrogen and Oxygen atoms:

MnCO3+2H2O ------->MnO2+HCO3-+2e-+3H+

The half reaction for the oxidation of Manganese has been [tex]\rm MnCO_3\;+\;2\;H_2O\;\rightarrow\;MnO_2\;+\;HCO_3^-\;+\;2e^-\;+\;3\;H^+[/tex]

Oxidation has been defined as the loss of electrons by an element. The half reaction has been the oxidation reaction in the redox reaction.

In the reaction of Manganese carbonate to manganese dioxide, there has been change in the oxidation number of Mn from +2 to +4. The change in the oxidation state has been balanced with the addition of electrons.

The carbonate charge has been balanced in the reaction with the addition of hydrogen and water molecules.

The half reaction for the oxidation of Manganese has been [tex]\rm MnCO_3\;+\;2\;H_2O\;\rightarrow\;MnO_2\;+\;HCO_3^-\;+\;2e^-\;+\;3\;H^+[/tex]

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Answer:

A. 0.433 moles of HNO₃

B. 6.07×10⁻⁵ moles of NaCl

C.  3.51×10⁻³ moles of sucrose

Explanation:

Part A.

Molarity . volume = moles

1.70 mol/L . 0.255L = 0.433 moles

Part B.

1.35 m of NaCl means, a molal concentration (m). Moles of solute in 1kg of solvent.

Let's convert 1 kg to mg for the rule of three

1 kg = 1×10⁶ mg

So in 1×10⁶ mg of solvent, we have 1.35 moles of solute (NaCl)

In 45 mg, we would have ( 45 . 1.35) / 1×10⁶ = 6.07×10⁻⁵ moles of NaCl

Part C. 1.50 % by mass means, 1.50 g of solute, in 100g of solution.

Let's make a rule of three:

In 100 g of solution we have 1.50 g of sucrose

In 80 g of solution, we would have (80 . 1.50) / 100 =1.2 g of sucrose.

Then, let's convert the mass in moles ( mass / molar mass)

1.2 g / 342 g/m = 3.51×10⁻³ moles

(A) 0.433 moles of HNO₃ in 255mL of 1.70M HNO3

(B) 6.07×10⁻⁵ moles of NaCl in 45.0mg of an aqueous solution that is 1.35m NaCl

(C) 3.51×10⁻³ moles of sucrose in an aqueous solution that is 1.50% sucrose (C12H22O11) by mass

(A) 255mL of 1.70M HNO3(aq)

Molarity × volume = moles

1.70 × 0.255L = 0.433 moles of HNO3

(B) 45.0mg of an aqueous solution that is 1.35m NaCl

1.35 m of NaCl means, a molal concentration (m). Moles of solute in 1kg of solvent.

In 45 mg, the number of moles is:

45 × 1.35 / 1×10⁶ = 6.07×10⁻⁵ moles of NaCl

(C) 80.0g of an aqueous solution that is 1.50% sucrose (C12H22O11) by mass

the solute is 1.50 % by mass, that is :

1.50 g of solute, in 100g of solution.

In 80 g of solution

80 × 1.50 / 100 =1.2 g of sucrose.

Now, convert the mass in moles

number of moles = given mass / molar mass

1.2 g / 342 g/m = 3.51×10⁻³ moles of sucrose

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Answer: B) an oxygen atom in a different molecule.

Explanation:

Hydrogen bonding (H-bonding) is an inter molecular force having partial ionic-covalent character.

H-bonding takes place between a hydrogen atom attached with an electronegative atom such as O, N and F and an electronegative atom such as O,N and F. They are strong forces.

Example: [tex]H_2O[/tex] has hydrogen bonding between hydrogen of one molecule with oxygen atom bonded to hydrogen of different molecule.

Thus the correct option is hydrogen bonding occurs between the hydrogen atom in one molecule and an oxygen atom in a different molecule.

In water, hydrogen bonding occurs between the hydrogen atom in one water molecule and the oxygen atom in a different water molecule. This is due to the large dipole moment caused by oxygen being more electronegative than hydrogen.

In a water molecule, hydrogen bonding occurs between the hydrogen atom of one molecule and an oxygen atom in a different molecule. Water molecules have a bent shape, with two hydrogen atoms and one oxygen atom. Because oxygen is more electronegative, the shared electrons between hydrogen and oxygen tend to stay closer to the oxygen atom, causing a dipole moment.

This dipole moment results in a partially positive charge on the hydrogen atoms and a partially negative charge on the oxygen atom. Hence, the hydrogen atoms from one water molecule are attracted to the oxygen atoms of another water molecule, forming hydrogen bonds.

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Answer: The correct choice is:

E) Both serine and leucine would be on the exterior of the globular protein.

Explanation:

The solubility and positioning of amino acids in a globular protein in aqueous solution are influenced by their side chains. Amino acids with hydrophilic (water-loving) side chains tend to be on the exterior of the protein where they can interact with water, while those with hydrophobic (water-fearing) side chains tend to be in the interior, away from water. In this case: Serine has a hydrophilic side chain (CH₂OH). Leucine has a hydrophobic side chain (CH₂CH(CH₃)₂). Therefore, you would expect serine to be on the exterior of the globular protein (interacting with water) and leucine to be in the interior (shielded from water). The correct choice is: E) Both serine and leucine would be on the exterior of the globular protein.

Answer:

The answer to your question is mass = 455.6 grams

Explanation:

Data

Dimensions = 68.6 yd x 12 in x 0.00035 in

density = 2.70 g/cm³

mass = ?

Process

1.- Convert dimensions to cm

              1 yd ---------------- 91.44 cm

            68.6 yd ------------  x

              x = (68.6 x 91.44) / 1

              x = 6227 cm

             1 in ----------------- 2.54 cm

            12 in ---------------   x

              x = (12 x 2.54) / 1

              x = 30.48 cm

              1 in --------------  2.54

  0.00035 in -------------  x

              x = (0.00035 x 2.54) / 1

              x = 0.000889 cm

2.- Find the volume of the foil

      V = 6227 x 30.48 x 0.000889

      V = 168.73 cm³

3.- Find the mass of the foil

      mass = density x volume

      mass = 2.70 x 168.73

      mass = 455.6 g

Final answer:

To calculate the mass of the aluminum foil, first convert all dimensions to centimeters, then calculate the volume (length × width × height), and finally multiply the volume by the density of aluminum (2.70 g/cm³). Therefore, the mass of the aluminum foil is approximately 457.94 grams

Explanation:

To find the mass of the aluminum foil given its dimensions and the density of aluminum, we need to follow these steps:

Convert all measurements to the same unit system, specifically to centimeters (cm) because the density is given in g/cm3.

Calculate the volume of the aluminum foil using the formula for the volume of a rectangular prism: Volume = length × width × height.

Multiply the volume by the density of aluminum to get the mass of the foil.

Step-by-Step Calculation

First, convert dimensions: 68.6 yd = 6265.44 cm (1 yd = 91.44 cm), 12 in = 30.48 cm (1 in = 2.54 cm), and 0.00035 in = 0.000889 cm.

Calculate the volume: Volume = 6265.44 cm × 30.48 cm × 0.000889 cm = 169.609 cm3.

Calculate the mass: Mass = volume × density = 169.609 cm3 × 2.70 g/cm3 = 457.94 grams.

The mass of the aluminum foil is approximately 457.94 grams.

Answer:

Kinetic Energy is involved here

Explanation:

On a warm day, the temperature of H20(l) will be high and that will make the particles of water to possess more kinetic energy and particles tend to move faster. Due to the fast movement of the particles, some of the particles turns into gaseous form (vapour). This makes the volume (concentration) of the liquid water decrease while that of the vapour keeps increasing due to the temperature of the day, until the equilibrium point is reached. At the equilibrium point, the forward and the backward rates are equal and the concentration of liquid water and vapour is the same.

Answer:

a) +640 kJ/mol or +1.06x10⁻¹⁸ J

b) +276 kJ/mol

Explanation:

To dissociate the molecule, the bond must be broken, thus, it's necessary energy equal to the energy of the bond, which can be calculated by:

E = (Q1*Q2)/(4*π*ε*r)

Where Q is the charge of the ions, ε is a constant (8.854x10⁻¹²C²J ⁻¹ m⁻¹), and r is the bond length. Each one of the ions has a charge equal to 1. The elementary charge is 1.602x10⁻¹⁹C, which will be the charge of them.

1 mol has 6.022x10²³ molecules (Avogadros' number), so the energy of 1 mol is the energy of 1 molecule multiplied by it:

E = 6.022x10²³ *(1.602x10⁻¹⁹)²/(4π*8.854x10⁻¹²*2.17x10⁻¹⁰)

E = +640113 J/mol

E = +640 kJ/mol

Or at 1 molecule: E =640/6.022x10²³ = +1.06x10⁻²¹ kJ = +1.06x10⁻¹⁸ J

b) The energy variation to dissociate the molecule at its neutral atoms is the energy of dissociation less the difference of the ionization energy of K and the electron affinity of F (EA):

498 = 640 - (418 - EA)

640 -418 + EA = 498

222 + EA = 498

EA = +276 kJ/mol

The energy required to dissociate the KF molecule into K+ and F- ions is -1.76 x [tex]10^5 kJ/mol.[/tex]n affinity of F is -80 kJ/mol.

To calculate the energy required to dissociate the KF molecule into the ions K+ and F-, we need to consider the bond length and the charges of the ions. The equation to calculate the energy is given by:

E = k * (q1 * q2) / r

where E is the energy, k is the Coulomb constant[tex](9 x 10^9 N m^2/C^2),[/tex]rges of the ions (+1 for K and -1 for F), and r is the bond length.

Using the given bond length, we have:

E = [tex](9 x 10^9 N m^2/C^2)[/tex](2.17 x[tex]10^-10 m)[/tex]

E = -[tex]1.06 x 10^18 J[/tex]

To convert this to kJ/mol, we divide by Avogadro's number:

E = -[tex]1.06 x 10^18 J / 6.022 x 10^23 mol-1[/tex]

E ≈ -[tex]1.76 x 10^5 kJ/mol[/tex]

To calculate the electron affinity (EA) for F, we can use the equation:

EA = Ionization Energy(K) - Dissociation Energy(KF) = 418 kJ/mol - 498 kJ/mol = -80 kJ/mol

Answer:D. Powder react with vinegar

Explanation: All the other choice is physical change. Choice A is a change of color but it doesn’t change the properties. Choice B is an example of physical change which is simply for measurements therefore doesn’t affect the properties. Choice C is also physical change because solubility and dissolve are type of physical change leaving us with the last choice which is choice D. Since the powder reacts with the vinegar it changes the property of the powder.

The reaction between the white powder and vinegar is a chemical property where the chemical bonds are involved in the change to produce new products.

There are broadly two types of properties called physical properties and chemical properties. Physical properties involves the color, size, shape , phase, and phase transitions etc. Boiling point, melting point, solubility etc are physical properties.

Chemical properties include the changes in chemical bond between atoms such as breaking or formation or both for chemical bonds. The reaction between two compounds leads to breaking and making of chemical bonds and form new products.

Density, solubility, color etc are physical properties of the substance whereas its reactivity towards vinegar is a chemical property. Hence, option D is correct.

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Answer:

A mole is equal to 6.022 × [tex]10^{23}[/tex] atoms/molecules.

Explanation:

A mole is a unit of measurement. Think of it as a unit of measurement just like a dozen of eggs is equal to 12 eggs, one mole is equal to 6.022 × [tex]10^{23}[/tex] atoms/molecules. This number, 6.022 × [tex]10^{23}[/tex], is known as Avogadro's number and you use it to convert from the number of moles to the number of atoms or molecules.

For example, if you want to convert 81 grams of water ([tex]H_{2}O[/tex]) to the number of atoms, you will need to use Avogadro's number. First, you have to find the molar mass of the water. To do this, you look at the periodic table and find the mass of hydrogen and oxygen because those are the elements that make up water. The subscript of the element tells you how many atoms of that particular element you have. So water has 2 hydrogen atoms and 1 oxygen atom. The molar mass tells you how many grams of a substance makes up 1 mole of that substance and it will vary by substance (no two different substances will have the exact same molar mass).

Molar Mass of Water: (2 × 1.008 g) + (1 × 15.999 g)= 18.015 grams

After we find the molar mass of the substance, we can use Avogadro's number to convert from grams to moles and then from moles to the number of atoms.

[tex]\frac{81 grams H_{2}O }{1} * \frac{1 mole H_{2}O }{18.015 grams H_{2}O } * \frac{6.022*10^{23} atoms}{1 mole H_{2}O } = 2.708*10^{24}[/tex] atoms of [tex]H_{2}O[/tex]

To convert grams to kilograms you need to know the conversion factor between them which is 1000 grams equals 1 kilogram. For example, if you are given 7,389 grams and you want to convert that to kilograms you do:

[tex]\frac{7389 grams}{1}[/tex] × [tex]\frac{1 kilogram}{1000 grams}[/tex] = 7.389 kilograms

I hope this helped clear things up a bit!

Answer: 1.83Litres

Explanation:

From Charles Law, the volume of a given mass of gas is directly proportional to temperature,provided that pressure remains constant.

V1/T1 =V2/T2

V1 = 1.5L

T1 =25+273=298K

T2 = 90+273= 363K

V2= ?

1.5/298 = V2/363

V2 = 1.5 × 363 /298

V2 = 1.8L

Therefore at 90 degree Celsius, volume of the balloon is 1.8Litres

Answer:

I2; I–I bond length = 266 pm

Explanation:

Bond length is inversely related to bond strength. The longer the bond length, the weaker the bond. The shorter the bond length the stronger the bond. A large bond distance implies that there is poor interaction between the atoms involved in the bond. A long bond distance or bond length may even indicate the absence of covalent interaction between the atoms involved.

Answer:

Oxygen and Carbon dioxide

Explanation:

Oxygen is required for respiration whereby energy is released from natural occurring nutrients accompanied by the release of water and carbon dioxide. carbon dioxideis also required by plants to photosynthesise.

Oxygen and carbon dioxide in the troposphere supports life as by enabling respiration in organisms and photosynthesise in plants can. Without oxygen in an environment, only life forms that live by anaerobic respiration will thrive. This affects a regions carrying capacity

Answer:

                    Major Product = 4-chloro-4-methylcyclohex-1-ene

Explanation:

                     Alkene are the class of organic compounds which contain one or more double bonds between two carbon atoms. Alkenes are considered most reactive among the unsaturated hydrocarbons and they undergo addition reactions due to high electron density around the double bonds.

                      In given question it is written that we are provided with one equivalent of HCl while, our compound contains two double bonds (diene) so in selected starting material the HCl will be added across (hydrohalogenation reaction) the substituted double bond because it will give a more stable carbocation (tertiary carbocation) during the reaction course. Hence, as shown in reaction scheme 4-chloro-4-methylcyclohex-1-ene will be the major product.

Answer:

498.95 ml of formula per day

Explanation:

Baby body requirement of copper per day = 80.0. μg per Kg

Copper content of formula = 0.48 μg/mL.

Mass of baby = 6.60 lb

1 lb = 0.4536 Kg

6.6 lb = 2.9937 Kg

Therefore baby needs

80μg/Kg/day × 2.9937 Kg = 239.5μg/day of formula

But formula contains 0.48 μg/mL that means baby needs

(239.5 μg/day)÷0.48 μg/mL = 498.95 ml of formula per day

498.95 ml/day

Answer:

Sodium-calcium exchanger on the sarcolemma

Explanation:

The sodium-calcium exchanger which is an antiporter membrane protein, removes calcium from cells. The energy of the electrochemical gradient of sodium is used by allowing it to flow down its gradient while moving across the plasma membrane

A precipitation reaction is indicated by the formation of a solid that settles out when two aqueous solutions are mixed. The correct answer is Option b.

When two different aqueous solutions are mixed in a test tube, a precipitation reaction can be indicated by the formation of a solid that settles out. This occurs when two soluble compounds react to form an insoluble compound, which appears as a solid precipitate. Examples of precipitation reactions include mixing solutions of silver nitrate and sodium chloride to form a solid precipitate of silver chloride.

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Final answer:

The observation that most directly indicates a precipitation reaction when two aqueous solutions are mixed is b. A solid settles out, as this signifies the formation of a precipitate, which is a solid product of the reaction.

Explanation:

The question asks which observation is most indicative of a precipitation reaction when mixing two different aqueous solutions. Among the options given, the correct answer is b. A solid settles out. This is because a precipitation reaction involves the formation of a solid product, known as a precipitate, that separates from the clear solution. This precipitate can then typically be observed as sediment at the bottom of the test tube, or as a solid pellet if centrifugation is used. Options a, c, and d refer to other potential indicators of chemical reactions, such as gas formation, color change, and exothermic reactions, respectively, and while they may occur alongside precipitation, they are not as directly indicative of it.

Answer:

We need 28.5 mL of Calcium solution

Explanation:

Step 1: Data given

Density = 1.55 g/mL

Mass of calcium fluoride (CaF2) = 85.8 grams

Molar mass of CaF2 = 78.07 g/mol

Step 2: The balanced equation

Ca + 2HF → CaF2 + H2

Step 3: Calculate moles CaF2

Moles CaF2 = mass CaF2 / molar mass CaF2

Moles CaF2 = 85.8 grams / 78.07 g/mol

Moles = 1.10 moles

Step 4: Calculate moles of Ca

For 1 mol mol CaF2 we need 1 mol Ca^2+

For 1.10 moles CaF2, we need 1.10 moles Ca^2+

Step 5: Calculate mass of Ca^2+

Mass Ca^2+ = moles Ca^2+ / molar mass Ca^2+

Mass Ca^2+ = 1.10 moles * 40.08 g/mol

Mass Ca^2+ = 44.1 grams

Step 6: Calculate volume of Ca^2+

Volume Calcium = mass calcium / density

Volume calcium = 44.1 grams / 1.55 g/mL

Volume calcium = 28.45 mL ≈ 28.5 mL

We need 28.5 mL of Calcium solution

Answer:

The percentage of gold is 52.5 %

Explanation:

Step 1: Data given

Piece of gold jewelry that weighs 9.30 g and has a volume of 0.675 cm³

Density of gold = 19.3 g/cm³

Density of silver = 10.5 g/cm³

Step 2: Calculate the volume of gold

Density = mass/ volume

Mass = density (gold) * volume (gold) + density silver * volume silver

9.30 g= 19.3 * V(gold) + 10.5* (0.675 - V(gold))

9.30g = 19.3V(gold) + 7.0875 - 10.5V(gold)

2.2125 = 8.8(Vgold)

V(gold) = 0.2514 cm³

Step 3: Calculate the mass of gold

Mass gold = density * volume

Mass gold = 19.3 g/cm³ * 0.2514 cm³

Mass gold = 4.85 grams

Step 4: Calculate the percentage of gold

% gold = (mass gold / total mass) * 100%

% gold = (4.85 grams / 9.30 grams )*100%

% gold = 52.2 %

The percentage of gold is 52.5 %

Answer:

The answer to your question is pH = 9.08

Explanation:

Data

pH = ?

Concentration = 1.2 x 10⁻⁵ M

Process

1.- Calculate the pOH of the solution

Formula

   pOH = -log[OH⁻]

   pOH = -log[1.2 x 10⁻⁵]

   pOH = 4.92

2.- Calculate the pH

Formula

    pH = 14 - pOH

Substitution

    pH = 14 - 4.92

Result

    pH = 9.08