What two statements are true about a system?A) systems are a group of objects analyzed as one unit? B) energy that moves across a system boundaries is covered? C) only one way to define the boundary of a system? D) systems are made by humans?

The theoretical yield of MgO for Trial 1 is 0.348 g, and for Trial 2 is 0.307 g. The percent yield of MgO for Trial 1 is 58.0% and for Trial 2 is 159.2%. The average percent yield of MgO for the two trials is 108.6%.

To calculate the theoretical yield of MgO, we need to use the balanced chemical equation for the reaction between magnesium (Mg) and oxygen (O2) to form magnesium oxide (MgO):

2Mg + O₂ → 2MgO

According to the stoichiometry of this equation, 2 moles of Mg react with 1 mole of O2 to produce 2 moles of MgO. Therefore, we need to determine the number of moles of Mg in each trial and use the mole ratio to find the theoretical yield of MgO.

For Trial 1:

The mass of Mg used is: 26.682 g - 27.012 g = 0.330 g

The molar mass of Mg is 24.31 g/mol, so the number of moles of Mg is:

0.330 g / 24.31 g/mol = 0.0136 mol Mg

According to the balanced equation, 2 moles of Mg produce 2 moles of MgO, so the theoretical yield of MgO is:

0.0136 mol Mg x (2 mol MgO / 2 mol Mg) x (40.31 g MgO/mol) = 0.348 g MgO

For Trial 2:

The mass of Mg used is: 26.987 g - 26.695 g = 0.292 g

The number of moles of Mg is:

0.292 g / 24.31 g/mol = 0.0120 mol Mg

The theoretical yield of MgO is:

0.0120 mol Mg x (2 mol MgO / 2 mol Mg) x (40.31 g MgO/mol) = 0.307 g MgO

To calculate the percent yield of MgO, we need to use the following formula:

Percent yield = (actual yield / theoretical yield) x 100%

For Trial 1:

The actual yield of MgO is: 27.214 g - 27.012 g = 0.202 g MgO

The percent yield of MgO is:

(0.202 g / 0.348 g) x 100% = 58.0%

For Trial 2:

The actual yield of MgO is: 27.183 g - 26.695 g = 0.488 g MgO

The percent yield of MgO is:

(0.488 g / 0.307 g) x 100% = 159.2%

To calculate the average percent yield of MgO for the two trials, we add the percent yields and divide by 2:

Average percent yield = (58.0% + 159.2%) / 2 = 108.6%

Therefore, the theoretical yield of MgO for Trial 1 is 0.348 g, and for Trial 2 is 0.307 g. The percent yield of MgO for Trial 1 is 58.0% and for Trial 2 is 159.2%. The average percent yield of MgO for the two trials is 108.6%.

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To calculate the mass of KOH needed to make a 5 M solution in 185.5 mL, we need to use the formula:

mass = moles × molar mass

where moles is the amount of KOH in moles and molar mass is the mass of one mole of KOH.

We can calculate the moles of KOH as follows:

moles = Molarity × Volume (in liters)

First, we need to convert the volume from milliliters to liters:

185.5 mL = 0.1855 L

Now we can calculate the moles of KOH:

moles = 5 M × 0.1855 L = 0.9275 moles

The molar mass of KOH is 56.11 g/mol. Therefore, the mass of KOH needed is:

mass = 0.9275 moles × 56.11 g/mol = 52.05 g

Therefore, 52.05 grams of KOH are needed to make a 5 M solution in 185.5 mL.

The number of molecules of BF₃ present in 2 grams of BF₃ is 1.776×10²² molecules (1st option)

We'll begin by calculating the number of mole of 2 grams of BF₃. Details below:

Mole = mass / molar mass

Mole of BF₃ = 2 / 67.81

Mole of BF₃ = 0.02949 mole

Finally, we shall determine the number of molecules of BF₃. This is shown below:

Avogadro's hypothesis suggest that:

1 mole of BF₃ = 6.022×10²³ molecules

Therefore,

0.02949 mole of BF₃ = 0.02949 × 6.02×10²³

0.02949 mole of BF₃ = 1.776×10²² molecules

Thus, the number of molecules of BF₃ is 1.776×10²² molecules (1st option)

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Answer:

V ≈ 2144.66 m³

Explanation:

Volume of sphere formula is:

V = 4/3 πr³

Radius is half the diameter so we divide the given diameter, 16 by 2 to get 8, the radius. Now we can solve

V = 4/3 π (8)³

V = 4/3 (512π)

V = 2048/3 π

V ≈ 2144.66 m³

Answer:

4/3 x π

Explanation:

The nucleus completing the following equation is option C: ₂₄⁵⁰Cr.

This reaction is a type of radioactive nuclei decay.

Radioactive decay is the process by which unstable atomic nuclei undergo spontaneous transformations in order to achieve a more stable state. This is accomplished by the emission of particles and/or electromagnetic radiation from the nucleus. The decay may occur by several mechanisms, including alpha decay, beta decay, gamma decay, and electron capture.

In alpha decay, the nucleus emits an alpha particle, which consists of two protons and two neutrons, resulting in a daughter nucleus that has two fewer protons and two fewer neutrons than the original nucleus.

In beta decay, a neutron in the nucleus is converted into a proton and an electron, and the electron is then emitted from the nucleus as a beta particle. This results in the daughter nucleus having one more proton and one fewer neutron than the original nucleus.

In gamma decay, the nucleus emits a gamma ray, which is a high-energy electromagnetic radiation, without changing the number of protons or neutrons in the nucleus.

In electron capture, an electron from the inner shell of the atom is captured by the nucleus, and a proton in the nucleus is converted into a neutron. This results in the daughter nucleus having one fewer proton and one more neutron than the original nucleus.

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Answer: C

Explanation:

Answer: C

Explanation:

The electronic configuration of the d-block metal ions in the 3d series is represented by electronic configuration of Argon (Ar), 3d and 4s sub orbitals.

The electronic configuration of the d-block metal ions in the 3d series is as follows:

Scandium (Sc): [Ar] 3d¹ 4s²

Titanium (Ti): [Ar] 3d² 4s²

Vanadium (V): [Ar] 3d³ 4s²

Chromium (Cr): [Ar] 3d⁵ 4s¹

Manganese (Mn): [Ar] 3d⁵ 4s²

Iron (Fe): [Ar] 3d⁶ 4s²

Cobalt (Co): [Ar] 3d⁷ 4s²

Nickel (Ni): [Ar] 3d⁸ 4s²

Copper (Cu): [Ar] 3d¹⁰ 4s¹

Zinc (Zn): [Ar] 3d¹⁰ 4s²

Thus, the above illustration shows the electronic configuration of all the metal ions in the d-blocks (3d series)​.

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The volume of O2 that can be released at STP from the given sample of silver oxide is 23.45 mL.

Creating the balanced chemical equation for the breakdown of silver oxide is the first step in tackling this issue:

2Ag2O(s) → 4Ag(s) + O2(g)

We can deduce from the equation that 2 moles of AgO will result in 1 mole of O2. Since Ag2O has a molar mass of 231.735 g/mol, 0.4856 g of Ag2O is equivalent to:

0.4856 g Ag2O x (1 mol Ag2O/231.735 g Ag2O) = 0.002095 mol Ag2O

Therefore, the number of moles of O2 that can be produced from 0.4856 g of Ag2O is:

0.002095 mol Ag2O x (1 mol O2/2 mol Ag2O) = 0.0010475 mol O2

1 mole of any gas takes up 22.4 L of space at STP As a result, 0.4856 g of Ag2O can generate the following amount of O2 at STP:

0.0010475 mol O2 x 22.4 L/mol = 0.02345 L or 23.45 mL

Therefore, the volume of O2 that can be released at STP from the given sample of silver oxide is 23.45 mL.

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B. To plot the data on a bar chart, draw a horizontal axis for metals and a vertical axis for time to complete the reaction. Then, draw bars for each metal that represent the amount of time required to complete the reaction. The height of the bars must match the time values ​​in the table.

C. No, Emilia was not correct in her forecast. According to the data, aluminum reacted 100 seconds faster than magnesium, which reacted in 50 seconds. Thus aluminum reacts more rapidly with hydrochloric acid than magnesium.

From most reactive to least reactive, the metals are as follows:

This order is consistent with the reactivity series, which is:

We are unable to estimate the reactivity of potassium, sodium, calcium, copper, silver, or gold from this experiment because those variables are not present in the data.

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To find the pH of the solution, we need to first calculate the concentration of H+ ions in the solution using the following equation:

[H+] = (moles of HCl) / (volume of solution in liters)

First, let's convert the mass of HCl to moles:

moles of HCl = mass / molar mass = 4.0 g / 36.46 g/mol = 0.1096 moles

Next, let's convert the volume to liters:

475 mL = 0.475 L

Now we can calculate the concentration of H+ ions:

[H+] = 0.1096 moles / 0.475 L = 0.2306 M

Finally, we can calculate the pH using the equation:

pH = -log[H+]

pH = -log(0.2306) = 0.637

Therefore, the pH of the solution is approximately 0.637.

Answer:

Explanation:

Both 2CH4 and C2H8 have the same number and kind of elements. But practically, 2CH4 will be existing but C2H8 cannot exist.

The mass of silver oxide needed to decompose in order to produce 120.6 grams of silver is 494.5 grams.

The balanced chemical equation for silver oxide breakdown is:

[tex]Ag_2O[/tex] → [tex]2 Ag[/tex] + [tex]1/2 O_2[/tex]

The equation shows that for every mole of silver oxide that decomposes, two moles of silver are created, and the molar mass of [tex]Ag_2O[/tex] is 231.74 g/mol.

Hence, using stoichiometry, we can calculate the quantity of silver oxide necessary to generate 120.6 grams of silver:

120.6 g Ag × (1 mol Ag / 107.87 g Ag) × (1 mol [tex]Ag_2O[/tex]/ 2 mol Ag) × (231.74 g [tex]Ag_2O[/tex] / 1 mol [tex]Ag_2O[/tex] )

= 494.5 g [tex]Ag_2O[/tex]

As a result, 494.5 grams of silver oxide is needed to decompose in order to produce 120.6 grams of silver.

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Answer:

The Correct answer is option 3

Step by Syep Explanation:

4Fe+3O2---->rust

formula for rust----->Fe2O3

4Fe+3O2---->Fe2O3

Balancing the Chemical Equation

both the reactant and product side

we have that;

4Fe+3O2------->2FeO3

the equation is Chemically Balanced

therefore 4Fe+3O2------->2×rust

Answer:

Explanation:

Given that,

Law of conservation of mass states that " Mass of reactants is equal to the mass of products".

Also we know that In a balanced equation the total number of atoms in the reactants equals the total number of atoms in the product.

We are given with 4Fe + 3O₂ i.e the reactant.

First Let's calculate the number of atoms in the reactant.

Now, Let's find the product .

Also, We can see 2Fe₂O₃ (Product)

4Fe + 3O₂ → 2Fe₂O₃

Number of atoms in the reactants = the total number of atoms in the product.

Therefore, 2Fe₂O₃ (Option 3) will the required answer .

Question #3: 0.8 g of NaHCO3 mass NaCI weight: 0.4 g 0.8 g/84 g/mol, or 0.0095 moles, of NaHCO3 0.4 g/58.5 g/mol = 0.0068 moles of NaCI are the moles.

The reaction's mole to mole ratio and the ratio in the balanced equation (1:1) are in agreement. The highest quantity of NaCI that may be produced from this reaction is 0.0095 moles since NaHCO3 is the limiting reactant.

The theoretical yield of NaCI is 0.0095 moles, which is question #6. The finished product weighs 0.4 g. The percent yield is 0.4 g/0.0095 moles times 100, which is 42.1%.

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The balanced chemical equation for the reaction between hydrochloric acid (HCl) and sodium bicarbonate [tex](NaHCO_3)[/tex] is:

[tex]HCl + NaHCO_3\ - > NaCl + CO_2 + H_2O[/tex]

The coefficients in the balanced equation show that 1 mole of HCl reacts with 1 mole of [tex]NaHCO_3[/tex] to produce 1 mole of NaCl, 1 mole of [tex]CO_2[/tex], and 1 mole of [tex]H_2O[/tex]. We need to find the number of moles of [tex](NaHCO_3)[/tex] present in the tablet.

2 grams of [tex]NaHCO_3[/tex] is equivalent to 0.02 moles, and 18 grams of HCl is equivalent to 0.45 moles. Since [tex](NaHCO_3)[/tex] is limiting reagent, only 0.02 moles of NaCl and [tex]CO_2[/tex] will be produced. The molar mass of [tex]CO_2[/tex] is 44 g/mol, so the mass of [tex]CO_2[/tex] produced is 0.88 g. The molar mass of NaCl is 58.44 g/mol, mass of NaCl produced is 1.17 g.

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Answer:

90g

Explanation:

Ans. 90 gram

we know that,

n = wt/m.wt

where, n=  moles

wt.= weight

m.wt = molecular weight

putting values we get

5 = wt./18 ( molecular weight of water is 18

wt.= 90

hence  ans.= 90 gram

The ΔG value for the reaction A (aq) + B (aq) → C(aq) at 25 °C and the given concentrations is -8.35 kJ/mol.

The relationship between ΔG and K is given by the following equation:

ΔG = -RTln(K)

where R is the gas constant (8.314 J/(mol·K)), T is the temperature in Kelvin (25 °C = 298.15 K), and ln denotes the natural logarithm.

To calculate K, we need to use the equilibrium expression and the given concentrations:

[tex]K = [C]/([A][B])[/tex]

[tex]K = (5.00 * 10^{-5} M)/((1.50 M)(1.00 M))[/tex]

[tex]K = 3.33 x 10^{-5}[/tex]

Now we can substitute the values for R, T, and K into the equation for ΔG:

ΔG = -RTln(K)

ΔG = [tex]-(8.314 J/(mol.K))(298.15 K)ln(3.33 x 10^{-5})[/tex]

ΔG = -8.35 kJ/mol

Therefore, the ΔG value for the reaction A (aq) + B (aq) → C(aq) at 25 °C and the given concentrations is -8.35 kJ/mol.

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The molarity of the solution that has 2.0 moles of solute in 3.0 L of solution is 0.67 mol/L

Molarity is  described as a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution.

Molarity = moles of solute / liters of solution

we then substitute the given values, and have

Molarity = 2.0 moles / 3.0 L

Molarity = 0.67 mol/L

Molarity is  very important because the ration used to express the concentration of  any  solution.

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Answer:

we need to know the definitions of the two types of mutations:

Looking at the definitions, we can see that a chromosomal mutation can affect many genes at once, while a gene mutation can affect only one or a few nucleotides. Therefore, a chromosomal mutation could have the most drastic effect on a gene, because it could alter or delete an entire gene or multiple genes, resulting in major changes in the phenotype or function of an organism. A gene mutation could also have significant effects on a gene, but it could also be silent or minor depending on the location and type of the mutation. Therefore, the answer is a chromosomal mutation. One possible way to back up this choice is to give an example of a chromosomal mutation that causes a genetic disorder, such as Down syndrome or Turner syndrome.

To solve this problem, we can use the formula:

q = m × c × ΔT

where q is the heat absorbed or released, m is the mass of the substance, c is its specific heat, and ΔT is the change in temperature.

First, let's calculate the mass of water:

m = 225.0 g

Next, let's calculate the heat absorbed by the water:

q_water = m × c × ΔT

q_water = 225.0 g × 4.184 J/(g·°C) × (24.60°C - 20.53°C)

q_water = 3749.8 J

Since the metal released 4274 J of heat, the heat absorbed by the calorimeter can be calculated by subtracting the heat absorbed by the water from the total heat released by the metal:

q_calorimeter = - (q_water + q_metal)

q_calorimeter = - (3749.8 J + 4274 J)

q_calorimeter = - 8023.8 J

Therefore, the heat absorbed by the calorimeter is -8023.8 J, which is approximately equal to -8000 J or -8.0 kJ. The answer is (c) -339 J, since it is the closest to the calculated value when rounded to the nearest integer. Note that the negative sign indicates that the calorimeter absorbed the heat, which is expected since the reaction involved a release of heat.

Answer: 6.11 L

Explanation:

STP= 1atm, 273.15K

Molar mass of CO2=44.01g/mol so n= (12.0/44.01)

PV=nRT

V=(nRT)/P

V=((12.0/44.01)(0.0821)(273.15))/1

V=6.11L

Answer:

Atomic number of sodium is 11

Electronic configuration of a sodium atom :

Since sodium has one electron in its outermost shell, Therefore, sodium can easily donate it's one electron. As the result it becomes sodium cation with + 1 charge.

Electronic configuration of a sodium cation,[tex] \: \sf ({Na}^{+1}) [/tex]

In case of sodium cation, it has fully filled electronic configuration.

Cations - Atoms that carry postive charge are called cations. Cations are formed when an atom loses its electron.

For example : [tex]\sf {Na}^{+} [/tex]

Anions - Atoms that carry negative charge are called anions. Anions are formed when an atom gains a electron.

For example : [tex]\sf {Cl}^{-} [/tex]

Johannes Brsted and Thomas M. Lowry, two chemists, identified the Bromsted-Lowry acids and bases as a particular kind of acid-base reaction in 1923.

Acids are substances that give a base a proton (H+), whereas bases are substances that take a proton from an acid. In a Bromsted-Lowry acid-base reaction, the acid gives the base a proton in order to create the conjugate base and the conjugate acid, two new compounds.

Nitric acid (HNO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl) are a few examples of acids. Sodium hydroxide (NaOH), ammonium hydroxide (NH4OH), and potassium hydroxide (KOH) are a few examples of bases.

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According to the information, we can infer that the difference between photographs 1 and 2 originate from the translation of the Moon around the earth (option C).

To explain the difference between both images we must take into account the movement patterns of the earth and the moon. In the case of the earth, it has 2 main movements, which are rotation on its own axis and translation around the sun.

On the other hand, the moon has a translational movement around the earth, which is what causes the different lunar phases. This motion causes the moon to appear partially shadowed from the earth because the earth blocks the sunlight.

Based on the above, we can infer that the correct answer is option C because this phenomenon is caused by the translation of the moon.

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The results of the lab activity showed that the larger the mass of the sun, the more likely at least one planet will fall into the habitable zone.

The mass of the sun affects the orbits of planets in a solar system. When the mass of the sun is larger, the gravitational force between the sun and the planets is stronger, causing the planets to move at a slower pace around the sun.

Conversely, when the mass of the sun is smaller, the gravitational force is weaker, causing the planets to move at a faster pace.

Additionally, when Earth is closer to the sun, the gravitational force is stronger, causing its orbit to become faster, while a farther distance from the sun results in a slower orbit.

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Using the Ideal Gas Law, the pressure expected for 30 mol of  [tex]C_2H_4[/tex] gas in a 6.00-L container at 20 °C is 1210.07 atm, and using the van der Waals equation, the pressure is 1179.71 atm.

To calculate the pressure expected for 30 mol of [tex]C_2H_4[/tex] gas in a 6.00-L container at 20 °C, we will use both the Ideal Gas Law and van der Waals equation.

Ideal Gas Law: PV = nRT
P = pressure
V = volume (6.00 L)
n = moles (30 mol)
R = ideal gas constant (0.0821 L•atm/mol•K)
T = temperature (20 °C + 273.15 = 293.15 K)

Solve for P (pressure):

P = nRT / V

P = (30 mol)(0.0821 L•atm/mol•K)(293.15 K) / 6.00 L

P = 1210.07 atm

Van der Waals equation:

(P + a(n/V)²)(V - nb) = nRT
a = 4.612 atm•L²/mol²
b = 0.0582 L/mol

Solve for P (pressure):
(P + (4.612)(30/6)²) (6 - 0.0582 * 30) = (30)(0.0821)(293.15)

P = 1179.71 atm

Using the Ideal Gas Law, the pressure is 1210.07 atm, and using the van der Waals equation, the pressure is 1179.71 atm.

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We need to carry at least 187 CCCs on board the space shuttle to absorb all the CO2 produced by the crew during the 18-day mission.

To solve this problem, we need to use the following information:

First, we need to calculate the total amount of CO2 that will be expelled during the mission:

Total CO2 = 6 crew members x 42.0 g CO2/hour x 24 hours/day x 18 days = 136,080 g CO2

Next, we need to calculate the amount of LIOH needed to absorb this CO2. The balanced chemical equation for the reaction between CO2 and LIOH is:

CO2 + 2 LIOH → Li2CO3 + H2O

The molar mass of CO2 is 44.01 g/mol, and the molar mass of LIOH is 23.95 g/mol.

This means that 2 moles of LIOH are needed to absorb 1 mole of CO2.

So, to absorb 136,080 g of CO2, we need:

136,080 g CO2 x (1 mol CO2/44.01 g) x (2 mol LIOH/1 mol CO2) x (23.95 g LIOH/1 mol) = 139,648 g LIOH

Since each CCC contains 750 g of LIOH, we need:

139,648 g LIOH / 750 g CCC = 186.2 CCCs

Therefore, we need to carry at least 187 CCCs on board the space shuttle to absorb all the CO2 produced by the crew during the 18-day mission.

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