Assuming complete dissociation, what is the ph of a 4.02 mg/l ba(oh)2 solution?

Explanation:

Isotopes are defined as the species which contain same number of protons but different number of neutrons.

As the sum of all the protons present in an atom is known as atomic number. Whereas the sum of total number of protons and neutrons is known as atomic mass.

Hence, isotopes are also defined as atoms with same atomic number but different atomic mass.

For example, an atom that has an atomic number of 20 and a mass number of 42 will contain the following number of neutrons.

                 Mass number = no. of protons + no. of neutrons

                            42 = 20 + no. of neutrons

                 no. of neutrons = 42 - 20

                                            = 22

So, isotope of this atom could be [tex]^{40}_{20}A[/tex]. This means that an element with atomic number of 20 and a mass number of 40.

Thus, we can conclude that an atom that has an atomic number of 20 and a mass number of 42 is an isotope of an atom that has an atomic number of 20 and a mass number of 40.

Since, both of them contains same number of protons but different number of neutrons.

The acidity or alkalinity of a solution depends upon the hydronium ion concentration and hydroxide ion concentration. If a solution has a hydronium ion concentration of 1x10⁻⁹ m the solution is basic. The correct option is B.

The pH of a solution is defined as the negative logarithm to the base 10 of the value of the hydronium ion concentration in moles per litre. The pH scale introduced by Sorensen is more convenient in expressing the hydronium ion concentration of a solution.

The pH can be calculated as:

pH = -log [H₃O⁺]

If the concentration of [H₃O⁺] is less than 10⁻⁷ M, then the solution is found to be basic.

Here pH is:

pH = - log [1 x 10⁻⁹]

= 9

So the pH of the solution is 9.

Thus the correct option is B.

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Final answer:

The Br2 molecule is nonpolar because it consists of two identical bromine atoms sharing electrons equally, leading to no permanent dipole moment.

Explanation:

When determining if a molecule such as Br2 is polar or nonpolar, molecular symmetry plays a key role. The molecule Br2 consists of two bromine atoms covalently bonded together. Since both atoms are the same and share electrons equally, the bond between them is nonpolar. Furthermore, because the molecule is made up of only two identical atoms, it has no molecular geometrical complexity that could lead to an uneven distribution of charge. In contrast, molecules like CO2 and H2O have polar bonds, but CO2 is nonpolar due to its linear shape causing the bond moments to cancel, while H2O is polar due to its bent shape and the presence of lone pairs on the oxygen atom which do not allow the bond moments to cancel out.

1) The answer is: mass of water is 1.35 grams.

Balanced chemical reaction: 2H₂ + O₂ → 2H₂O.

m(O₂) = 1.2 g; mass of oxygen.

M(O₂) = 2 · 16 g/mol.

M = 32 g/mol, molar mass of oxygen.

n(O₂) = m(O₂) ÷ M(O₂).

n(O₂) = 1.2 g ÷ 32 g/mol.

n(O₂) = 0.0375 mol; amount of oxygen, limiting reactant.

m(H₂) = 9.5 g; mass of hydrogen.

M(H₂) = 2 g/mol, molar mass of hydrogen.

n(H₂) = m(H₂) ÷ M(H₂).

n(H₂) = 9.5 g ÷ 2 g/mol.

n(H₂) = 4.5 mol; amount of hydrogen.

From chemical reaction: n(O₂) : n(H₂O) = 1 : 2.

n(H₂O) = 0.0375 mol · 2.

n(H₂O) = 0.075 mol; amount of water.

m(H₂O) = n(H₂O) · M(H₂O).

m(H₂O) = 0.075 mol · 18 g/mol.

m(H₂O) = 1.35 g; mass of water.

2) The answer is: 3.05 grams of MgCl₂ is produced, the limiting reactant is Mg(OH)₂.

Balanced chemical reaction: 2HCl + Mg(OH)₂ → MgCl₂ + 2H₂O.

m(Mg(OH)₂) = 1.85 g; mass of magnesium hydroxide

n(Mg(OH)₂) = m(Mg(OH)₂) ÷ M(Mg(OH)₂).

n(Mg(OH)₂) = 1.85 g ÷ 58.32 g/mol.

n(Mg(OH)₂) = 0.032 mol; limiting reactant.

m(HCl) = 3.71 g; mass of hydrochloric acid.

n(HCl) = 3.71 g ÷ 36.46 g/mol.

n(HCl) = 0.102 mol; amount of hydrochloric acid.

From chemical reaction: n(Mg(OH)₂) : n(MgCl₂) = 1 : 1.

n(MgCl₂) =0.032 mol; amount of magnesium chloride.

m(MgCl₂) = n(MgCl₂) · M(MgCl₂).

m(MgCl₂) = 0.032 mol · 95.21 g/mol.

m(MgCl₂) = 3.05 g; mass of magnesium chloride.

3) The answer is: mass of potassium hydroxide is 8.1 grams.

Balanced chemical reaction: K₂O + H₂O → 2KOH.

m(K₂O) = 8.2 g; mass of potassium oxide.

n(K₂O) = m(K₂O) ÷ M(K₂O).

n(K₂O) = 8.2 g ÷ 94.2 g/mol.

n(K₂O) = 0.087 mol; amount of potassium oxide.

m(H₂O) = 1.3 g; mass of water.

n(H₂O) = 1.3 g ÷ 18 g/mol.

n(H₂O) = 0.072 mol; limiting reactant.

From chemical reaction: n(H₂O) : n(KOH) = 1 : 2.

n(KOH) = 2 · 0.072 mol.

n(KOH) = 0.144 mol.

m(KOH) = 0.144 mol · 56.1 g/mol.

m(KOH) = 8.1 g; mass of potassium hydroxide.

4) The answer is: mass of aluminum chloride is 16.66 grams.

Balanced chemical reaction: 2Al + 3Cl₂ → 2AlCl₃.

m(Al) = 8.1 g; mass of aluminium.

n(Al) = m(Al) ÷ M(Al).

n(Al) = 8.1 g ÷ 27 g/mol.

n(Al) = 0.3 mol.

V(Cl₂) = 4.2 L; volume of chlorine.

n(Cl₂) = 4.2 L ÷ 22.4 L/mol.

n(Cl₂) = 0.1875 mol; limiting reactant.

From chemical reaction: n(Cl₂) : n(AlCl₃) = 3 : 2.

n(AlCl₃) = 2 · 0.1875 mol ÷ 3.

n(AlCl₃) = 0.125 mol; amount of aluminium chloride.

m(AlCl₃) = 0.125 mol · 133.34 g/mol.

m(AlCl₃) = 16.66 g; mass of aluminium chloride.

Answer:

4

Explanation:

Hot coffee is a homogeneous mixture, consisting of substances that are uniformly distributed and cannot be easily separated.

Hot coffee is neither an element nor a compound, but rather a type of mixture. Specifically, hot coffee is a homogeneous mixture. A mixture is a material composed of two or more substances that are combined without a chemical reaction occurring, and in a homogeneous mixture, these substances are uniformly distributed. Therefore, in the case of hot coffee, the coffee solids, water, and any added sugar or cream are thoroughly mixed and cannot be easily separated, which is typical of homogeneous mixtures.

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Hot coffee is a homogeneous mixture, characterized by a uniform composition throughout. It is not a heterogeneous mixture or a compound.

Hot coffee is an example of a homogeneous mixture. This classification is due to the uniform composition throughout the coffee, which is a combination of several substances including water, coffee solids, and possibly sugar or milk. It remains homogeneous due to the heat which keeps the solids dissolved. It differs from a heterogeneous mixture, where the composition varies from point to point, and also from a compound, which is a substance formed by chemical union of two or more elements. In contrast, the constituents of a mixture like coffee can be separated by physical changes, such as evaporation.

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To react with 0.13 g of acetylene, 0.399 grams of oxygen are needed based on the molar masses and the balanced chemical equation 2 C2H2 + 5 O2
ightarrow 4 CO2 + 2 H2O.

To find the number of grams of oxygen required to react with 0.13 g of acetylene, we need to use the balanced chemical equation for the reaction and the molar mass of acetylene (C2H2) and oxygen (O2). The balanced chemical equation is 2 C2H2 + 5 O2
ightarrow 4 CO2 + 2 H2O. First, we calculate the molar mass of acetylene, which is (2  imes 12.01 g/mol for carbon) + (2  imes 1.008 g/mol for hydrogen) = 26.04 g/mol. Next, we determine how many moles of acetylene 0.13 g corresponds to by using the molar mass:

moles of C2H2 = 0.13 g / 26.04 g/mol = 0.00499 mol

According to the balanced equation, 2 moles of C2H2 react with 5 moles of O2. Therefore, for 0.00499 moles of C2H2, the moles of O2 required are (0.00499 mol C2H2  imes 5 moles O2) / 2 moles C2H2 = 0.012475 moles O2.

The molar mass of O2 is (2  imes 16.00 g/mol) = 32.00 g/mol. Now, we'll convert moles of O2 to grams:

grams of O2 = 0.012475 moles  imes 32.00 g/mol = 0.399 grams of O2

Therefore, 0.399 grams of oxygen are required to react with 0.13 grams of acetylene.

Answer : Beta particle will balance the following nuclear equation.

Explanation :

The nuclear reaction is,

[tex]^{234}_{91}Pa\rightarrow ^{234}_{92}U+^{-1}_0\beta[/tex]

Beta particle : It forms when a neutron changes into a proton and a high-energy electron.

When the nucleus emits the beta particle,  the mass number remains same  and the atomic number increases by 1  and the nuclear charge increases by 1.

Hence, the Beta particle will balance the following nuclear equation.

If a gas effuses 4.0 times faster than oxygen (O2), the molecular mass of the gas is 2.0 g/mol.

The molecular mass of a gas can be calculated using Graham's equation of diffusion as follows:

R1/R2 = √M2/M1

Since the gas effuses 4.0 times faster than oxygen;

R1/4R1 = ✓32/M2

(1/16) = x/32

16x = 32

x = 2g/mol

Therefore, If a gas effuses 4.0 times faster than oxygen (O2), the molecular mass of the gas is 2.0 g/mol.

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The correct answer is that the gas will occupy a volume of approximately 99.53 ml at standard temperature.

To solve this problem, we will use Charles's Law, which states that the volume of a gas is directly proportional to its temperature in Kelvin, provided the pressure remains constant. The formula for Charles's Law is:

[tex]\[ \frac{V_1}{T_1} = \frac{V_2}{T_2} \][/tex]

where [tex]\( V_1 \) and \( T_1 \)[/tex] are the initial volume and temperature of the gas, and [tex]\( V_2 \) and \( T_2 \)[/tex] are the final volume and temperature.

First, we need to convert the given temperatures from Celsius to Kelvin:

[tex]\[ T_1 = 32^\circ C + 273.15 = 305.15 \text{ K} \][/tex]

[tex]\[ T_2 = 0^\circ C + 273.15 = 273.15 \text{ K} \] (standard temperature)[/tex]

Now we can rearrange Charles's Law to solve for [tex]\( V_2 \):[/tex]

[tex]\[ V_2 = V_1 \times \frac{T_2}{T_1} \][/tex]

Substitute the known values into the equation:

[tex]\[ V_2 = 111 \text{ ml} \times \frac{273.15 \text{ K}}{305.15 \text{ K}} \][/tex]

[tex]\[ V_2 = 111 \text{ ml} \times \frac{273.15}{305.15} \][/tex]

[tex]\[ V_2 \approx 111 \text{ ml} \times 0.896 \][/tex]

[tex]\[ V_2 \approx 99.5315 \text{ ml} \][/tex]

However, we must note that the standard pressure is typically considered to be 1 atmosphere (atm), and since the problem does not specify a change in pressure, we assume that the pressure remains constant. Therefore, the final volume at standard temperature and pressure (STP) is:

[tex]\[ V_2 \approx 99.5315 \text{ ml} \][/tex]

But, to be more precise, we should consider that STP is defined as 0°C (273.15 K) and 1 atm, where the molar volume of an ideal gas is 22.414 liters per mole. Since we are not given the moles of gas or the pressure, we will assume that the pressure is 1 atm, and thus the volume will change only due to temperature.

Given that the initial volume is 111 ml, and we have already calculated the ratio of the temperatures, the final volume at STP is:

[tex]\[ V_2 = 111 \text{ ml} \times 0.896 \][/tex]

[tex]\[ V_2 \approx 99.5315 \text{ ml} \][/tex]

Rounding to two decimal places, we get:

[tex]\[ V_2 \approx 99.53 \text{ ml} \][/tex]

However, there seems to be a discrepancy between the initially stated answer of 95.66 ml and the calculated answer of 99.53 ml. To ensure accuracy, let's re-evaluate the calculation:

[tex]\[ V_2 = 111 \text{ ml} \times \frac{273.15 \text{ K}}{305.15 \text{ K}} \][/tex]

[tex]\[ V_2 \approx 111 \text{ ml} \times 0.896 \][/tex]

[tex]\[ V_2 \approx 99.5315 \text{ ml} \][/tex]

The balanced chemical equation for the reaction between Hydrochloric acid (HCl) and potassium hydroxide (KOH) is: HCl + KOH → KCl + H₂O.

A student has asked for the balanced chemical equations for Hydrochloric acid and potassium hydroxide. The balanced chemical equation for the reaction between Hydrochloric acid (HCl) and potassium hydroxide (KOH) is:

HCl + KOH → KCl + H₂O

In this neutralization reaction, Hydrochloric acid (a strong acid) reacts with potassium hydroxide (a strong base) to produce potassium chloride (a salt) and water. This type of reaction is typical between acids and bases where the hydrogen ion (H⁺) from the acid combines with the hydroxide ion (OH⁻) from the base to form water.

Answer: The correct answer is option D.

Explanation: Super-giant stars are the stars which are greater than Sun. They have a mass hundred time greater than Sun and can be thousand times greater than Sun.

The masses of the stars are represented in Solar masses which is the mass of the Sun.

Mass of Betelgeuse = 20 Solar masses

Mass of Pollux = 1.7 Solar masses

Mass of Sirius = 2.02 Solar masses

Mass of Sun = 1 Solar mass.

As, the mass of Sun is the least from the given stars. Hence, it is least considered as a super-giant.

Final answer:

Pollux is the least likely to be categorized as a supergiant since it is an evolved giant star, while Betelgeuse is a known red supergiant, and both Sirius A and the Sun are main-sequence stars.

Explanation:

The star least likely to be categorized as a super giant among the options provided is Pollux. Betelgeuse is a well-known red super giant that is visible near Orion's belt as the bright red star marking the hunter's shoulder. Pollux, in contrast, is classified as an evolved giant star (a red giant), which is a less massive and less luminous stage compared to a super giant. Option B

Sirius A, known for being the brightest star in the sky after the Sun, is a main-sequence star, and also not a super giant. The Sun itself is a main-sequence star, not nearly massive enough to ever become a super giant. Therefore, while neither Pollux, Sirius A, nor the Sun are super giants, Pollux being an evolved giant is the furthest in its life cycle from the super giant category compared to the main-sequence state of Sirius A and the Sun.

Answer: When the electron moves from the first energy level to the second energy level, energy is absorbed.

Explanation:

When an electron moves from first energy level to the second energy level,energy is being absorbed by the atom which means that the electron jumps from lower energy level to higher energy level.

Bohr's Equation

E=[tex]\frac{-E_0}{n^2}[/tex]

where,

E= energy of an  electron in 'n' level (n=1,2,3...etc)

[tex]E_0[/tex]= energy of an electron in ground state.

as we can see from this equation energy is inversely proportional to the n principle quantum number which means that there will be decrease in energy. As the energy is decreasing in magnitude with the negative sign  which actually means there is increase in energy.

The given balanced reaction is,

[tex] 4Fe(s) + 3O_{2}(g) --->2Fe_{2}O_{3} (s) [/tex]

The stoichiometric coefficients of each element or compound represents the number of moles of that element or compound required for the complete reaction to take place.

The mole ratios of different products and reactants will be:

[tex] \frac{Fe}{O_{2}} = \frac{4 mol Fe}{3 mol O_{2}} [/tex]

[tex] \frac{Fe}{Fe_{2}O_{3}} = \frac{4 mol Fe}{2 Fe_{2}O_{3}} [/tex]

[tex] \frac{O_{2}}{Fe_{2}O_{3}} =\frac{3 mol O_{2}}{2molFe_{2}O_{3}} [/tex]

So the mole ratio comparing iron (Fe) and oxygen gas ([tex] O_{2} [/tex]) is

4 : 3

The total pressure in a 6.00-L flask with a mixture of 0.127 mol H₂ and 0.288 mol N₂ at 20.0°C is calculated using the ideal gas law PV = nRT. After converting the temperature to Kelvin and determining the total moles of gas, the pressure is found to be approximately 1.68 atm.

To calculate the total pressure in a 6.00-L flask containing 0.127 mol of H₂(g) and 0.288 mol of N₂(g) at 20.0°C, we can use the ideal gas law, which is PV = nRT. Here, P is the pressure, V is the volume, n is the number of moles of gas, R is the ideal gas constant, and T is the temperature in Kelvin.

First, convert temperature from Celsius to Kelvin: T = 20.0 + 273.15 = 293.15 K.

Next, use R = 0.0821 L·atm/(K·mol), which is the ideal gas constant appropriate when pressure is in atmospheres and volume is in liters.

Combine the moles of gases: total moles (n₂₄₂al) = 0.127 mol H₂ + 0.288 mol N₂ = 0.415 mol.

Then calculated the pressure using the ideal gas law: P = (nRT)/V = (0.415 mol * 0.0821 L·atm/(K·mol) * 293.15 K) / 6.00 L = 1.68 atm (rounded to two decimal places).

The total pressure in the flask at 20.0°C is therefore approximately 1.68 atmospheres.

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Answer:

what he/she/they said

Explanation:

Answer:

I - 131 is the correct answer.

I - 131 is the only naturally occuring radioactive isotope among these four options.

Explanation:

Np - 239 - Neptunium is also considered as an artificial element,as only trace amounts of it are found in nature.

And Np - 239 is not a naturally occuring radioactive isotope but it is synthesized artificially.

No - This is an artificial element.That means its not found in nature. Hence all its isotopes are also synthesized artificially.

Cm - This is also an artificial element and all its isotopes are also synthesized artificially.

Np - 239,No - 254,Cm - 242 are radioactive isotopes but they are not naturally occuring radioactive isotopes. But these three are artificially made radioactive isotopes.

And Iodine - 131 is the only naturally occuring radioisotope among these.

The correct answer is option (b).  At STP, two 5.0-gram solid samples of different ionic compounds have the same density. These solid samples could be dominated by their crystal structures.

A) Molar masses: The molar mass of a compound refers to the mass of one mole of that substance. While the molar mass affects the mass of the compound, it does not directly determine the density unless the volume occupied by the same mass of different compounds is considered.

B) Crystal structures: The crystal structure refers to the arrangement of ions in a solid. If two ionic compounds have the same density, it is likely that their ions are packed in a similar manner, resulting in the same volume for the same mass. The crystal structure determines how closely the ions are packed together, which directly influences the density.

C) Ionic charges: While ionic charges influence the electrostatic forces between ions, they do not directly determine the density of a solid. The arrangement of ions (crystal structure) has a more direct impact on density than the charges of the ions themselves.

D) **Solubilities**: The solubility of a compound refers to how well it dissolves in a solvent, such as water. This property does not affect the density of the solid form of the compound.

The complete question is:

At STP, two 5.0-gram solid samples of different ionic compounds have the same density. These solid samples could be dominated by their __________.

A) molar masses  

B) crystal structures  

C) ionic charges  

D) solubilities  

Which property could be a dominant factor for these solid samples to have the same density?

Answer:

The correct answer is C. Meteoroids are smaller than comets and asteroids

Explanation:  Asteroids go as far as a kilometer in size while meteoroids can be as big as a house. Comets are out of all comparison as they can be up to 80 000 km long.

1. All are moving

2. Are dense and difficult to compress

3.

All are correct... 3/3 100%