What’s the oxidation number of copper in CuO?

The chemical formula for the ionic compound barium iodide is [tex]BaI_2[/tex] .

Barium iodide is composed of one barium ion (Ba2+) and two iodide ions (I-), which together form a neutral compound. Barium iodide is a white crystalline solid with a high melting point and is soluble in water. It is commonly used in the manufacture of photographic paper and in the production of cathode ray tubes for televisions and computer monitors.

Barium iodide has a variety of other uses, including in medicine as a contrast agent for X-ray imaging and in the synthesis of organic compounds.

The compound has several different crystal structures, including hexagonal and cubic, and can be prepared by reacting barium carbonate with hydroiodic acid. Overall, barium iodide is an important and versatile compound with a range of practical applications.

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After considering the given data and performing the evaluation regarding the convertion of energy units the answer derived is 6.61 x 10⁶ J = 1577.16 kcal.

In order to alter joules (J) to kilocalories (kcal), the below conversion can be applied.
1 kcal = 4.184 kJ.
We start by, converting J to kJ by dividing by 1000:
6.61 x 10⁶ J = 6.61 x 10³ kJ
Next step we convert kJ to kcal by dividing by 4.184:
= 6.61 x 10³ kJ ÷ 4.184
= 1577.16 kcal (rounded to five significant figures)

1 joule (J) is the amount of energy needed to apply a force of 1 newton (N) over a distance of 1 meter (m).
1 kilocalorie (kcal), on the other hand, is described as the amount of energy required to increase the temperature of 1 kilogram (kg) of water by 1 degree Celsius (°C), which is equal to 4184 joules (J).
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The equation that shows that the total mass during a chemical reaction stays the same is 2) H₂ + O₂ → H₂O.

This is an example of a balanced chemical equation where the number of atoms of each element on both the reactant and product side is equal. In other words, the total number of atoms of each element is conserved, and therefore the total mass is conserved. In the other reactions, either the number of atoms on the product side is different from the reactant side or there is no reaction at all.

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The balanced chemical equation for the electrolysis of water is:

2H2O → 2H2 + O2

This equation shows that for every two moles of water that are electrolyzed, one mole of oxygen gas is produced. To solve this problem, we need to first convert the given mass of water (83.7 grams) to moles of water.

The molar mass of water (H2O) is:

2(1.008 g/mol H) + 15.999 g/mol O = 18.015 g/mol

So, 83.7 grams of water is equal to:

83.7 g / 18.015 g/mol = 4.646 mol H2O

Next, we need to determine how many moles of oxygen gas will be produced when 4.646 moles of water are electrolyzed. Since the mole ratio of water to oxygen is 2:1, we can use the following proportion:

2 mol H2O : 1 mol O2 = 4.646 mol H2O : x mol O2

Solving for x, we get:

x mol O2 = (1 mol O2 / 2 mol H2O) * 4.646 mol H2O = 2.323 mol O2

Finally, we can convert the moles of oxygen gas produced to grams using the molar mass of oxygen:

2.323 mol O2 * 32.00 g/mol O2 = 74.3 g O2

Therefore, 83.7 grams of water will produce 74.3 grams of oxygen gas by electrolysis.

We need 21 grams of potassium chloride to make a 50 mL saturated solution at 40 degrees Celsius. It's important to note that if the temperature or volume of the solution were to change, the amount of solute needed to make a saturated solution would also change, as solubility is dependent on both temperature and volume.

According to the solubility table, the solubility of potassium chloride at 40 degrees Celsius is 42 grams per 100 mL of water. This means that we can dissolve 42 grams of potassium chloride in 100 mL of water at 40 degrees Celsius to make a saturated solution.

To make a 50 mL saturated solution, we can use the following formula:
mass of solute = (volume of solution x solubility)/100
mass of solute = (50 x 42)/100
mass of solute = 21 grams
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Mark would need a thermometer to determine the temperature change of a solution during a chemical reaction. A thermometer is a tool used to measure temperature and can be used to monitor and record changes in temperature during a chemical reaction. So the answer is thermometer .

There are different types of thermometers, such as liquid-in-glass thermometers, bimetallic strip thermometers, digital thermometers, and infrared thermometers, among others. The choice of thermometer depends on the specific requirements of the experiment or process being carried out.

By measuring the initial and final temperatures of the solution before and after the chemical reaction, Mark can determine the temperature change, which is an important parameter in many chemical reactions as it provides information about the heat energy involved in the reaction, and helps in understanding the thermodynamics and kinetics of the process. Therefore the answer is thermometer .

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The best statement that describes the three enzymes is: The enzymes have different structures because they have a different sequence of amino acids. Opton A is correct.

Enzymes are biological catalysts that facilitate chemical reactions in living organisms. Enzymes are proteins, and their function is determined by their three-dimensional structure, which is determined by the sequence of amino acids that make up the protein.

In this scenario, the three enzymes have different structures, which suggests that they have a different sequence of amino acids. This difference in amino acid sequence results in different folding patterns and ultimately different shapes of the enzymes. The specific shape of an enzyme determines its ability to catalyze a particular chemical reaction. Hence, the different structures of these enzymes indicate that they may perform different functions or catalyze different chemical reactions.

Option A, "The enzymes have different structures because they have a different sequence of amino acids," is the correct answer as it aligns with the fundamental principle of protein structure and function.

Option B, "The enzymes have the same sequence of amino acids because they are all digestive enzymes," is incorrect because enzymes can have different sequences of amino acids even if they perform the same function.

Option C, "The enzymes perform different functions because they have the same sequence of amino acids," is incorrect because the sequence of amino acids determines the enzyme's structure and thus its function.

Option D, "The enzymes break down the same molecules because they have a different sequence of amino acids," is also incorrect because different amino acid sequences can result in different substrate specificity, which means that the enzymes can break down different molecules. Therefore option A is correct.

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The correct molar mass for nickel chloride is 94.14 g/mol (option C).

Molar mass is the mass of a given substance divided by its amount, measured in moles. It is commonly expressed in grams (sometimes kilograms) per mole.

The molar mass of a substance can be calculated by summing up the atomic masses of the element components.

According to this question, the atomic mass of nickel is 58.693 amu while that of chlorine gas is 35.45 amu. The molar mass of nickel chloride can be calculated as follows;

molar mass = 35.45 amu + 58.693 amu = 94.14 g/mol

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To determine the change in enthalpy associated with the generation of 155.3 g of [tex]C_5H_1_0O[/tex] we must first calculate the moles of [tex]C_5H_1_0O[/tex] produced using its molar mass.

The molar mass of C₅H₁₀O is:

5(12.01 g/mol) + 10(1.01 g/mol) + 16.00 g/mol = 88.15 g/mol

Moles of C₅H₁₀O produced:

155.3 g / 88.15 g/mol = 1.763 mol C₅H₁₀O

The balanced chemical equation states that the formation of 1 mol of C₅H₁₀O results in an enthalpy change of -191.3 kJ.

As a result, the enthalpy change during the formation of 1.763 mol of C₅H₁₀O is: -191.3 kJ/mol x 1.763 mol = -337.8 kJ

The enthalpy change for the production of 155.3 g of C5H10O is -337.8 kJ.

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There are 15.4 equivalents of chloride ion present in the solution

We need to multiply the total number of moles of chloride ion in the solution by the number of equivalents.

The molar mass of NaCl is 58.44 g/mol, so 3.5 mol of NaCl contains :

3.5 mol NaCl x 2 mol Cl⁻/1 mol NaCl = 7 mol Cl⁻

Similarly, the molar mass of MgCl₂ is 95.21 g/mol, so 4.2 mol of MgCl₂ contains:

4.2 mol MgCl₂ x 2 mol Cl⁻/1 mol MgCl₂ = 8.4 mol Cl⁻

Therefore, the total number of moles of chloride ion in the solution is:

7 mol Cl⁻ + 8.4 mol Cl⁻ = 15.4 mol Cl⁻

By dividing the total number of moles by the number of equivalents per mole, we can finally determine how many equivalents of the chloride ion there are. There is one equivalent of the chloride ion per mole since it has a valency of -1.

15.4 mol Cl⁻ x 1 eq/mol = 15.4 eq

So there are 15.4 equivalents of chloride ion present in the solution.

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a. [C]: [tex]HCl[/tex] or any other strong acid b. [S]: Lead acetate or any other heavy metal salt c. [I]: Lead nitrate or silver nitrate

a. To confirm the presence of [tex]CO_32[/tex]-, a solution of dilute [tex]HCl[/tex] (hydrochloric acid) is added. If [tex]CO_32[/tex]- is present, it will react with the [tex]HCl[/tex] to produce [tex]CO_2[/tex] gas, which can be identified by bubbling it through limewater [tex](Ca(OH)_2)[/tex].

b. To confirm the presence of [tex]S_2[/tex]-, a solution of lead acetate [tex](Pb(CH_3COO)_2)[/tex] is added. If [tex]S_2[/tex]- is present, it will react with the lead acetate to produce a black precipitate of lead sulfide ([tex]PbS[/tex]).

c. To confirm the presence of I-, a solution of chlorine water ([tex]Cl_2[/tex] in water) is added. If I- is present, it will react with the chlorine to produce a brown color, which is due to the formation of iodine (I2).

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The specific heat capacity of the ring, given that the ring gives up 667.5 J of energy to the water is 0.444 J/gºC. The ring is made of nickel.

The specific heat capacity of the ring can be obtain as illustrated below:

Q = MCΔT

-667.5 = 25.5 × C × -59

-667.5 = -1504.5 × C

Divide both sides by -1504.5

C = -667.5 / -1504.5

C = 0.444 J/gºC

Thus, the specific heat capacity of the ring is 0.444 J/gºC. Hence, the ring is made of nickel

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The value of H (in kJ) when 5.10 g of H2(g) is formed is 326 kJ (option B).

The given reaction is: CH3OH(I) —> CO(g)+2H2(g)

From the given value of H, we know that when one mole of CH3OH reacts, 128.1 kJ of heat energy is absorbed.

The molar mass of H2 is 2 g/mol. So, 5.10 g of H2 is equivalent to 5.10/2 = 2.55 moles of H2.

From the balanced equation, we can see that two moles of H2 are produced for each mole of CH3OH that reacts.

So, 2.55 moles of H2 are produced by 1.275 moles of CH3OH reacting (2.55/2).

Therefore, the amount of heat energy absorbed when 1.275 moles of CH3OH reacts can be calculated as:

Q = n x ΔH = 1.275 mol x 128.1 kJ/mol = 163.28 kJ

Since this amount of heat energy is absorbed when 1.275 moles of CH3OH reacts, to find the amount of heat energy absorbed when 2.55 moles of H2 is formed, we can simply double the value of Q:

Q = 2 x 163.28 kJ = 326.56 kJ

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The net ionic equation of the reaction is as follows:

4 Al3+(aq) + 12 NO3-(aq) + 3 Ag(s) = 4 Al(s) + 12 Ag+(aq) + 12 NO3-(aq)

Ions which remain in their ground state and do not take part in the reaction are called spectator ions. The net ionic equation cancels out these ions, which are present on both the reactant and product sides of the equation.

Spectator ions, which can be found on both the reactant and product sides, but are not included in the finished reaction from the net ionic equation. The [tex]NO^3^-[/tex] ions are spectator ions in this example, thus taking them out of the equation. The net ionic equation makes up the rest of the species.

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The volume of C₂H₂ that is collected over water at 23 ∘C by the reaction of 1.52 g of CaC₂ is 0.61 L

First, we shall determine the mole of CaC₂ that reacted. Details below:

Mole = mass / molar mass

Mole of CaC₂ = 1.52 / 64

Mole of CaC₂ = 0.024 mole

Next, we shall determine the mole of C₂H₂. obtained. Details below:

CaC₂ + 2H₂O -> C₂H₂ + Ca(OH)₂

From the balanced equation above,

1 mole of CaC₂ reacted to produced 1 mole of C₂H₂

Therefore,

0.024 mole of CaC₂ will also react to produce 0.024 mole of C₂H₂

Finally, we shall determine the volume of C₂H₂ collected. This is shown below:

PV = nRT

729.93 × V = 0.024 × 62.36 × 296

Divide both sides by 729.93

V = (0.024 × 62.36 × 296) / 729.93

V = 0.61 L

Thus, the volume of the C₂H₂ gas collected is 0.61 L

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Explanation:

Table H lists vapor pressure data for pure water at various temperatures. We can use this data to estimate the vapor pressure of the water in the given system at its final temperature of 80.0°C.

First, we need to calculate the heat absorbed by the water sample during the heating process. We can use the specific heat capacity of water to do this:

q = m * c * ΔT

where q is the heat absorbed, m is the mass of water (100 g), c is the specific heat capacity of water, and ΔT is the temperature change (80°C - 30°C = 50°C).

Plugging in the values, we get:

q = 100 g * 4.18 J/(g*C) * 50 C

q = 20900 J

This tells us that 20,900 joules of energy were absorbed by the water sample during heating.

Next, we need to consider the saturated solution of KCIO3 in the water sample. At 80.0°C, the water is already close to boiling, so it is likely that the vapor pressure of the water in the system is close to the vapor pressure of pure water at this temperature. From Table H, we can see that the vapor pressure of pure water is approximately 356 mmHg at 80.0°C.

Therefore, the vapor pressure of the water in the given system at its final temperature of 80.0°C is approximately 356 mmHg.

Chemical reactions nearly always include a change in energy between the products and reactants.

Thus, Energy is released when chemical bonds are created and is released when chemical bonds are destroyed.

The overall energy of a system, however, must remain constant according to the Law of Conservation of Energy, and chemical reactions frequently absorb or release energy in the form of heat, light, or both.

The difference in the amounts of chemical energy that are stored in the products and reactants accounts for the energy change in a chemical reaction. Enthalpy refers to the system's heat content or stored chemical energy.

Thus, Chemical reactions nearly always include a change in energy between the products and reactants.

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For strong electrolytes, molar conductivity decreases as the solution is diluted because the concentration of ions decreases.

For weak electrolytes, molar conductivity increases as the solution is diluted because as the solution is diluted, the concentration of ions increases.

The expression for the dilution law is A = εcb

The conductivity of a solution containing one mole of an electrolyte when placed between two electrodes spaced one centimeter apart is known as the molar conductivity of the electrolyte. The strength of the electrolyte affects how molar conductivity changes with dilution.

At infinite dilution, the molar conductivity of an electrolyte reaches its maximum value because the electrolyte's ions are so far apart that they no longer interact with one another.

The dilution law or Beer-Lambert law states that the absorbance of a solution is directly proportional to the concentration of the solution and the path length of the light through the solution.

A ∝ cb

Adding a proportionality constant gives:

A = εcb

where;

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The mass of the HI that is produced is  1843 g

Stoichiometry is a branch of chemistry that focuses on the quantitative relationships in chemical reactions between reactants and products.

What is the number of moles?

Number of moles of [tex]N_{2} H_{4}[/tex] = 115.7 g/32 g/mol

= 3.6 moles

Now we have that the balanced reaction equation is;

[tex]N_{2} H_{4} + 2I_{2} --- > N_{2} + 4 HI[/tex]

If 1 mole of [tex]N_{2} H_{4}[/tex] produces 4 moles of HI

3.6 moles of [tex]N_{2} H_{4}[/tex] will produce 3.6 * 4/1

= 14.4 moles of HI

Mass of HI produced = 14.4 moles * 128 g/mol

= 1843 g

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Answer:

3.8 ⋅*10^-14

Explanation:

The standard free energy change (ΔG°) for the reaction at 298 K can be calculated using the following equation:

ΔG° = ΣnΔGf°(products) - ΣnΔGf°(reactants)

where ΔGf° is the standard molar free energy of formation of the species and n is the stoichiometric coefficient.

ΔG° = [1×ΔGf°(Fe2O3)] - [1×ΔGf°(FeO) + 1×ΔGf°(Fe) + 1×ΔGf°(O2)]

ΔG° = [1×(-822.16 kJ/mol)] - [1×(-271.9 kJ/mol) + 1×(0 kJ/mol) + 1×(0 kJ/mol)]

ΔG° = -550.26 kJ/mol

The standard enthalpy change (ΔH°) and standard entropy change (ΔS°) can be used to calculate the standard free energy change (ΔG°) at any temperature using the following equation:

ΔG° = ΔH° - TΔS°

where T is the temperature in Kelvin.

ΔG° = ΔH° - TΔS° = (-550.26 kJ/mol) - (298 K)(-0.08996 kJ/K/mol) = -524.05 kJ/mol

Now, we can calculate the equilibrium constant (K) for the reaction at 298 K using the following equation:

ΔG° = -RTlnK

where R is the gas constant (8.314 J/K/mol) and T is the temperature in Kelvin.

-524.05 kJ/mol = -(8.314 J/K/mol)(298 K)lnK

lnK = -200.16

K = e^(-200.16) = 3.89×10^(-87)

Therefore, the value of K for the reaction at 25 °C is 3.89×10^(-87). Answer: 3.8 ⋅*10^-14.

Answer: Moss

Explanation: It's a flowerless plant

The minimum concentration of fluoride ions necessary to precipitate [tex]CaF_2[/tex] from a [tex]5.25 * 10^{-3}[/tex] M solution of [tex]Ca(NO_3)_2[/tex] is [tex]6.09 * 10^{-5}[/tex] M.

The solubility product expression for [tex]CaF_2[/tex] is:

[tex]Ksp = [Ca_2^+}][F^-]^2[/tex]

We can use this expression to find the minimum concentration of fluoride ions necessary to precipitate [tex]CaF_2[/tex] from a [tex]5.25 * 10^{-3} M[/tex] solution of [tex]Ca(NO_3)_2[/tex].

First, we need to determine the initial concentration of [tex]Ca_2^+[/tex] ions in solution. Since [tex]Ca(NO_3)_2[/tex] dissociates into two [tex]Ca_2^+[/tex] ions and two [tex]NO_3^-[/tex]ions, the initial concentration of [tex]Ca_2^+[/tex] ions is:

[tex]Ca_2^+[/tex] = [tex]2 * 5.25 * 10^{-3} M = 1.05 * 10^{-2} M[/tex]

Next, we can use the solubility product expression to solve for the minimum concentration of fluoride ions required to precipitate [tex]CaF_2[/tex]:

Ksp = [[tex]Ca_2^+[/tex]][tex][F^-]^2[/tex]

[tex]3.9 * 10^{-11} = (1.05 * 10^{-2} M)([F^-]^2)[/tex]

[tex][F^-]^2 = (3.9 * 10^{-11})/(1.05 * 10^{-2} M) = 3.71 * 10^{-9}[/tex]

[tex][F^-] = \sqrt{(3.71 * 10^{-9}) } = 6.09 * 10^{-5} M[/tex]

Therefore, the minimum concentration of fluoride ions necessary to precipitate [tex]CaF_2[/tex] from a [tex]5.25 * 10^{-3}[/tex] M solution of [tex]Ca(NO_3)_2[/tex] is [tex]6.09 * 10^{-5}[/tex]M.

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the answer is 2.5 according to me

We can use the combined gas law to determine the pressure of the gas at the final state. The combined gas law relates the pressure, volume, and temperature of a gas:

(P1 x V1) / T1 = (P2 x V2) / T2

where P1, V1, and T1 are the pressure, volume, and temperature of the gas at the initial state, and P2, V2, and T2 are the pressure, volume, and temperature of the gas at the final state.

We are given the initial pressure (P1 = 1.01 atm), volume (V1 = 2.31 L), and temperature (T1 = 279 K) of the gas, and the final volume (V2 = 1.09 L), and temperature (T2 = 308 K) of the gas. We can solve for P2, the final pressure of the gas:

(P1 x V1) / T1 = (P2 x V2) / T2

P2 = (P1 x V1 x T2) / (V2 x T1)

P2 = (1.01 atm x 2.31 L x 308 K) / (1.09 L x 279 K)

P2 = 2.41 atm (rounded to three significant figures)

Therefore, the pressure of the gas when the volume is 1.09 L and the temperature is 308 K is approximately 2.41 atm.

To solve this problem, we need to use the balanced chemical equation for the reaction between zinc (Zn) and hydrochloric acid (HCl):

[tex]Zn + 2HCl - > ZnCl_2 + H_2[/tex]

According to the stoichiometry of this equation, one mole of Zn reacts with two moles of HCl to produce one mole of H2. Therefore, we need to determine the number of moles of Zn in 25 g, and then use the mole ratio to find the number of moles of H2 produced.

Finally, we can convert the number of moles of H2 to volume at STP using the molar volume of a gas.

First, we need to calculate the number of moles of Zn in 25 g:

The molar mass of Zn is 65.38 g/mol

The number of moles of Zn in 25 g is:

25 g / 65.38 g/mol = 0.383 mol Zn

Next, we use the mole ratio from the balanced equation to find the number of moles of H2 produced:

According to the balanced equation, one mole of Zn reacts with one-half mole of H2, so we produce 0.5 x 0.383 = 0.192 mol H2.

Finally, we can use the molar volume of a gas at STP to convert the number of moles of H2 to volume:

The molar volume of a gas at STP is 22.4 dm3/mol

Therefore, the volume of H2 produced is:

V = (0.192 mol) x (22.4 dm3/mol) = 4.30 dm3 or 4,300 ml

Therefore, the volume of hydrogen gas produced at STP is 4.30 dm3 or 4,300 ml when 25 g of zinc is added to excess dilute hydrochloric acid at 31°C and 778 mm Hg pressure.

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The aluminum block absorbed 0.875 kJ of heat energy when it was dropped into the coffee.

let's calculate the heat lost by the coffee when it is cooled from its initial temperature of 90.0°C to its final temperature of 55.0°C:

Q1 = m1 * C1 * (90.0°C - 55.0°C)

Q1 = 850 g * 4.184 J/g °C * (90.0°C - 55.0°C)

Q1 = 125660 J

where m1 is the mass of the coffee, C1 is the specific heat of water.

Next, let's calculate the heat gained by the aluminum block when it is heated from 4.4°C to the final temperature of the mixture, which is 55.0°C:

Q2 = m2 * C2 * (55.0°C - 4.4°C)

Q2 = 18 g * 0.89 J/g °C * (55.0°C - 4.4°C)

Q2 = 875.16 J

where m2 is the mass of the aluminum block, and C2 is the specific heat of aluminum.

Since the energy lost by the coffee is gained by the aluminum block, we can set Q1 equal to Q2:

Q1 = Q2

125660 J = 875.16 J + m2 * C2 * (55.0°C - 4.4°C)

Solving for m2, we get:

m2 = (125660 J - 875.16 J) / (0.89 J/g °C * (55.0°C - 4.4°C))

m2 = 152.2 g

Therefore, the mass of the aluminum block that was dropped into the coffee is 152.2 g. To calculate the heat energy absorbed by the aluminum block, we can use the heat gained by the aluminum block that we calculated earlier:

Q2 = 875.16 J

Converting this to kJ, we get:

Q2 = 0.875 kJ

Therefore, the aluminum block absorbed 0.875 kJ of heat energy when it was dropped into the coffee.

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Answer:

A position-time graph can support the statement that a positive slope results when an individual is moving away from the origin. This is because a positive slope on a position-time graph represents a positive velocity, which means that the object is moving in a positive direction (away from the origin). Conversely, a negative slope would indicate that the object is moving in a negative direction (towards the origin).

Option A and B are incorrect. A negative slope on a position-time graph indicates that the object is moving towards the origin, not away from it. A horizontal line on a position-time graph indicates that the object is not moving at all (velocity is zero), not moving at a non-zero velocity.

Option D is also incorrect. The speed of an individual can be determined from a position-time graph by calculating the slope of the graph at any point, which gives the velocity (speed and direction) of the individual at that point..

mark me brilliant

Answer:

Explanation:

a) The balanced equation for the double replacement reaction between lead (II) nitrate and potassium bromide is:

Pb(NO₃)₂(aq) + 2KBr(aq) → PbBr₂(s) + 2KNO₃(aq)

In this reaction, lead (II) bromide (PbBr₂) will precipitate, while potassium nitrate (KNO₃) will remain in solution.

b) To determine the amount of precipitate produced, we need to first determine the limiting reactant. We can do this by calculating the number of moles of each reactant and comparing it to the stoichiometry of the balanced equation.

The molar mass of lead (II) nitrate is 331.21 g/mol and the molar mass of potassium bromide is 119.00 g/mol.

The number of moles of lead (II) nitrate is 32.5 g / 331.21 g/mol = 0.0981 mol The number of moles of potassium bromide is 38.75 g / 119.00 g/mol = 0.3256 mol

According to the balanced equation, one mole of lead (II) nitrate reacts with two moles of potassium bromide to produce one mole of lead (II) bromide. This means that if all the lead (II) nitrate were to react, it would require 0.0981 mol * 2 = 0.1962 mol of potassium bromide.

Since we have more than enough potassium bromide (0.3256 mol > 0.1962 mol), lead (II) nitrate is the limiting reactant.

The number of moles of lead (II) bromide produced will be equal to the number of moles of lead (II) nitrate consumed, which is 0.0981 mol.

The molar mass of lead (II) bromide is 367.01 g/mol, so the mass of lead (II) bromide produced will be 0.0981 mol * 367.01 g/mol = 36.0 g.

c) To determine the amount of excess reactant remaining, we need to subtract the amount consumed from the initial amount.

The number of moles of potassium bromide consumed is half the number of moles of lead (II) nitrate consumed, which is 0.0981 mol / 2 = 0.04905 mol.

The mass of potassium bromide consumed is 0.04905 mol * 119.00 g/mol = 5.84 g.

The mass of potassium bromide remaining is 38.75 g - 5.84 g = 32.91 g.

Answer:

Br, Se, Sr, Rb

Explanation:

Atomic radius increases as you move to the left and down the periodic table. The increase in radius as you move left is due to decreasing effective nuclear charge (the pull an electron feels from the nucleus) since the number of protons decrease. The increase in radius as you move down is due to a higher number of principle energy levels (orbital in which the electron is located relative to the atom's nucleus), causing the electrons to be farther from the nucleus.

20 g of calcium would release the same number of valence electrons as 23 g of sodium.

The atomic number of calcium (Ca) is 20, which means it has 20 electrons in its neutral state. When calcium loses two electrons, it becomes a Ca2+ ion with 18 electrons.

On the other hand, the atomic number of sodium (Na) is 11, which means it has 11 electrons in its neutral state. When sodium loses one electron, it becomes a Na+ ion with 10 electrons.

To release the same number of valence electrons as 23 g of Na, we need to calculate how many moles of Na there are in 23 g:

Molar mass of Na = 23 g/mol

Number of moles of Na = 23 g / 23 g/mol = 1 mol

Since each Na+ ion has lost one electron, 1 mol of Na+ ions has lost 1 mol of valence electrons.

To release the same number of valence electrons as 1 mol of Na+ ions, we need to calculate how many moles of Ca2+ ions are required:

1 mol of Na+ ions = 1 mol of valence electrons

1 mol of Ca2+ ions = 2 mol of valence electrons

Therefore, we need 0.5 mol of Ca2+ ions to release the same number of valence electrons as 1 mol of Na+ ions.

Finally, we can calculate the mass of calcium that would release the same number of valence electrons as 23 g of Na:

Molar mass of Ca = 40 g/mol

Mass of Ca required = 0.5 mol x 40 g/mol = 20 g

Therefore, 20 g of calcium would release the same number of valence electrons as 23 g of sodium.

learn more about valence electrons here

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