Science (middle school work)

The change in entropy for each reaction is;

1)  -198 J/mol

2) -5 J/mol

3) -148 J/mol

The change in entropy, denoted as ΔS, is a measure of the amount of disorder or randomness in a system before and after a process or reaction. It is defined as the difference between the entropy of the final state and the entropy of the initial state.

The formula for calculating the change in entropy is:

ΔS = S_final - S_initial

where ΔS is the change in entropy, S_final is the entropy of the final state, and S_initial is the entropy of the initial state.

We have that;

1) 2(192.5) - [3(130.58) + 191.50]

= 385 - [391.74 + 191.50]

= -198 J/mol

2) [213.6 + 2(188.83] - [186.3 + 2(205]

= -5 J/mol

3) 2(220) - [2(191.50) + 205]

-148 J/mol

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The minimum volume of a 0.100 M calcium hydroxide solution required to neutralize all of the dimethylglycine is 41.2 mL.

The balanced chemical equation for the reaction between dimethylglycine and calcium hydroxide is:

N(CH3)2CH2COOH + Ca(OH)2 → Ca(N(CH3)2CH2COO)2 + 2H2O

From the equation, we can see that 1 mole of dimethylglycine reacts with 1 mole of calcium hydroxide. We can use this information to calculate the amount of calcium hydroxide required to neutralize the acid.

First, we need to determine the number of moles of dimethylglycine in the sample:

molar mass of dimethylglycine = 115.13 g/mol

number of moles = 475 mg / 1000 mg/g / 115.13 g/mol = 0.00412 mol

Since 1 mole of dimethylglycine reacts with 1 mole of calcium hydroxide, we need 0.00412 mol of calcium hydroxide to neutralize the acid.

Finally, we can use the molarity of the calcium hydroxide solution to determine the volume required:

moles of Ca(OH)2 = 0.00412 mol

volume of Ca(OH)2 solution = moles / molarity = 0.00412 mol / 0.100 mol/L = 0.0412 L

Converting this to milliliters:

volume of Ca(OH)2 solution = 41.2 mL

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The type of solution would you have if you have a sealed container with 100g of water and 0.15g of dissolved CO₂ at 40°C is a saturated solution.

A saturated solution is a solution that has dissolved as much solute as it is capable of dissolving. In a saturated solution, no more solute can be dissolved at a given temperature. We can make an saturated solution by keep on dissolving solute until no more solute can be dissolved.

Given,

mass of water = 100g

mass of dissolved CO₂ = 0.15g  

Solubility = (weight of solute ÷ weight of solvent)×100

Solubility = (0.15 ÷ 100)×100 = 0.15g

Therefore, the type of solution would you have if you have a sealed container with 100g of water and 0.15g of dissolved CO₂ at 40°C is a saturated solution.

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Answer:

saturated

Explanation:

The density of a substance is its mass divided by volume. The density of the substance with a mass of 108.75 g and volume of 75 ml is 1.45 g/ml.

The density of a substance is the  measure of its mass per unit volume. Density describes how closely its particles are packed. The density of a substance depends on the bond type, molecular weight, temperature and pressure as well.

The floating property of a substance on a fluid depends on its density. If it has less density than the fluid it will float on it.

Given,

the mass of the object m = 108.75 g

volume = 75 ml

density = mass/ volume

d = 108.75 g /75 ml

   = 1.45 g/ml.

Therefore, the density of the substance with the mass of 108.75 g and 75 ml volume is 1.45 g/ml.

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In aquaponics, the ammonia present in water is converted into nitrates which is used by the plants as a nutrients which is a chemical change. When the mass is converted into energy, it increases the temperature of the ecosystem and also the earth surface indicating a physical change.

Chemical changes are defined as changes which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical change.

There are several characteristics of chemical changes like change in color, change in state , change in odor and change in composition . During chemical change there is also formation of precipitate an insoluble mass of substance or even evolution of gases.

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The number of moles present in the 1.2×10²⁴ molecules of the sample is 2 moles

The number of mole of the sugar in the sample containing 1.2×10²⁴ molecules can be obtained as follow:

From Avogadro's hypothesis,

6.022×10²³ molecules = 1 mole of NaCl

Therefore, we can say that

1.2×10²⁴ molecules = 1.2×10²⁴ / 6.022×10²³

3.011×10²³ molecules = 2 mole of sugar

Thus, the number of mole of sugar present is 2 mole

From the above calculation, we can see that we started with molecules and we ended in moles

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Answer: Your welcome!

Explanation:

Answer 1: Ice, water, sugar, lemon juice

Answer 2: Liquid in a gas

Answer 3: Saturated

Answer 4: Dissolution

Answer 5: Moles of solute/liters of solution

Answer 6: Strong electrolytes completely dissociate in water, weak electrolytes partially dissociate, and nonelectrolytes do not dissociate.

Answer 7: Molarity

Answer 8: Saturated

Answer 9: Freezing-point depression

Answer 10: Silver chloride (AgCl)

To solve this problem, we first need to use stoichiometry to determine the number of moles of O2 produced by the decomposition of 37.25 grams of KCIO3.

From the balanced equation, we know that 2 moles of KCIO3 decompose to produce 3 moles of O2. Therefore, we can use the molar mass of KCIO3 to convert 37.25 grams to moles:

37.25 g KCIO3 x (1 mol KCIO3/ 122.55 g KCIO3) = 0.3032 mol KCIO3

Using the stoichiometry of the balanced equation, we can convert the moles of KCIO3 to moles of O2:

0.3032 mol KCIO3 x (3 mol O2/ 2 mol KCIO3) = 0.4548 mol O2

Now that we know the number of moles of O2 produced, we can use the ideal gas law to calculate the volume of gas produced at the given temperature and pressure.

V = nRT/P

Where:

V = volume of gas (in liters)

n = number of moles of gas

R = ideal gas constant (0.0821 L·atm/K·mol)

T = temperature (in Kelvin)

P = pressure (in atm)

First, we need to convert the temperature to Kelvin:

12.43°C + 273.15 = 285.58 K

Now we can substitute the values into the ideal gas law equation:

V = (0.4548 mol)(0.0821 L·atm/K·mol)(285.58 K)/(941.34 kPa/101.325 kPa/atm)

V = 0.0151 L or 15.1 mL (rounded to three decimal places)

Therefore, 37.25 grams of KCIO3 will produce 15.1 mL of O2 at a temperature of 12.43°C and 941.34 kPa.

If we have 100 g of O₂,  the mass in  grams of Al₂O₃ will be produced is 477.8 g.

The chemical equation is as follows :

4Al (s) + 3O₂ (g) ==> 2Al₂O₃ (s)

The mass of the O₂  = 100 g

The molar mass of the O₂ = 32 g/mol

The moles of the O₂ = 100 g / 32 g/mol

The moles of the O₂ = 3.125 mol

The 3 moles of the O₂ produces the 2 moles of the Al₂O₃

The moles of the Al₂O₃ = (2/3 ) 3.125

The moles of the Al₂O₃ = 4.687 mol

The mass of the  Al₂O₃ = moles × molar mass

The mass of the Al₂O₃ = 4.687 × 101.96

The mass of the Al₂O₃ = 477.8 g

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Over-watering and aggressive plowing can have a variety of negative effects on the land used for crop production.

How are these activities likely to have impacted the land?

Some potential consequences of these practices include:

Overall, these activities can have a negative impact on the health of the land and reduce its productivity over time. To mitigate these effects, it may be necessary to adopt more sustainable farming practices, such as conservation tillage and crop rotation, that help to preserve the health of the soil and maintain its productivity.

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Lead cannot melt at such level, hence it cannot break down into individual atoms or molecules. A change in the bonding of atoms or molecules is referred to as melting.

The metallic connections are broken and the atoms are made more mobile by the energy needed to melt the metal. Atoms have the same kinetic energy as they did as a solid at a particular temperature, such as the melting point.

No, an atom cannot be melted. The three common states of matter no longer hold true when you are dealing with so tiny a piece. Atoms do not alter until by nuclear fission or fusion.

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The reagent which is completely consumed in a reaction and thereby limits how much product can be formed is called the limiting reagent. Here the limiting reagent is O₂.

The quantity of the product which is actually made compared with the maximum calculated yield is defined as the percent yield. The percent yield is the ratio of the actual yield to the theoretical yield.

% Yield = Actual yield / Theoretical yield × 100

The number of moles (n) = Given mass / Molar mass

'n' of C₂H₄ = 170.9 / 28.05 = 6.09 mol

'n' of O₂ = 64.1 / 31.9 = 1.65 mol

So O₂ is the limiting reactant.

Theoretical yield of CO₂ is:

170.9 × 1 mol / 28 g × 2 mol / 1 × 44/1 = 537.1 g CO₂

%Yield = 64.1 / 537.1 × 100 = 11.93 %

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Your question is complete most probably your full question was:

In an experiment, 170.9 g of C_{2}*H_{4} was reacted with 52.75g of O₂, 64.1 g of C*O_{2} is produced .What is the limiting reagent? ) What is the percent yield of this reaction?

Knowing each element's mass and molar mass allows one to compute the percentage of zinc and copper that is present in a coin.

The mass in grams from one mole of a chemical is its molar mass. A mole is the measurement of the number of things, such as atoms, molecules, and ions, that are present in a substance. Any material has 6.022 x 1023 molecules in a mole.

A substance's molar mass is the volume of the material that contains one mole of the substance. Its basic definition seems to be the weight of a single mole of a substance. The atomic mass of the each substance then multiplied by the subscript of such a element inside the chemical formula to determine the molar mass.

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The cost (in dollar) of running your 100 watt light bulb at the time per month is $ 14.4

First, we shall determine the energy consumed per month by the light bulb

E = Pt

E = 0.1 × 720

E = 72 KWh

Finally, we shall determine the cost of running the light bulb. Details below

Cost = energy × Cost per KWh

Cost of running per month = 72 × 0.2

Cost of running per month = $ 14.4

Thus, we can conclude that the cost of running per month is $ 14.4

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Using the masses of reactants and products the balanced chemical equations are:

a)C₃H₈ + 5O₂ ⇒ 3CO₂ + 4H₂O

b) C₂H₅OH  + 3O₂ ⇒ 2CO₂ + 3H₂O

c) C₁₄H₃₀ ⇒ C₇H₁₆ + C₃H₈ + 2C₂H₄(cracking)

Equations are balanced when they have the same number of each element on both the reactant and product sides. Equations need to be balanced in order to express the conservation of mass rule appropriately.

To balance chemical equations, stoichiometric coefficients for the reactants and products are necessary. Because a chemical equation must adhere to the rules of conservation of mass and constant proportions, the reactant and product sides of the equation must have an equal number of atoms of each element.

Long chain hydrocarbons, also known as kerogens, are complex chemical molecules that can be broken down into lighter, simpler molecules by a process called cracking. It results from the dissolution of carbon-carbon bonds. The presence of a catalyst and temperature are two elements that have a significant impact on the catalyst rate.

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The periodic chart is a tabular collection of chemical elements arranged according to atomic number, starting with hydrogen and going up to oganesson, which has the greatest atomic number.

In the periodic table, also referred to as the periodic chart of the (chemical) elements, the chemical elements are organised in rows and columns. It is frequently used in physics, chemistry, and other academic fields and is widely recognised as a sign of chemistry.

This is a visual representation of the periodic law, which states that the properties of molecular elements depend approximately periodically on their atomic numbers. There are four roughly rectangular "pieces" that make up the table's top.

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The measurement of the Earth, Moon, and distance from each other using 1/64 scale is 55600 km that will 1/64 of earths size.

The Moon is just 1/4 the size of Earth, with a diameter of 2,159 miles (3,475 kilometres).

The average distance between the Moon and Earth is 238,000 miles (383,500 km).

Orbit around Earth: It takes the Moon 27.3 Earth days to complete one orbit around our planet.

The Moon rotates on its axis once every 27.3 Earth days.

Surface features include craters, mountain ranges, rilles (long, narrow channels), and lava plains. The enormous, dark areas seen on the Moon's surface are known as maria, or seas. These are, in fact, massive, smooth lava beds. Highlands are brilliant, luminous patches on the Moon's surface.

Around 500 miles (800 kilometres) of the Moon's surface is covered by a solid, rocky crust.

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Energy in chemical reactions involves the process in which it is absorbed to break bonds, and energy is evolved as bonds are made.

This is referred to as a process in which one or more substances, the reactants, are converted to one or more different substances, the products.

According to the modern view of chemical reactions, bonds between atoms in the reactants must be broken, and the atoms or pieces of molecules are reassembled into products by forming new bonds. All chemical reactions involve energy changes ad in some reactions, we are able to observe these energy changes as either an increase or a decrease.

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The planet you are referring to is not a planet, but a celestial object called a comet. Comets are made up of frozen gas, rock, and dust and can develop a visible "tail" when they get close to the sun due to the heat causing the ice to vaporize and release gas and dust particles.

Answer: highwinds and earthquake

Explanation:

"What does a tuned mass damper do?

Image result for tuned mass damper

A Tuned Mass Damper (TMD), also called a "harmonic absorber", is a device mounted to a specific location in a structure, so as to reduce the amplitude of vibration to an acceptable level whenever a strong lateral force such as an earthquake or high winds hit"

The number of phases present is two.

There are two phases present in sweetened iced tea with sugar and ice cubes. The first phase is the liquid phase of the tea, which contains water, sugar, and other dissolved substances.

The second phase is the solid phase of ice cubes, which contains solid water molecules. These two phases are in contact with each other, and the sugar molecules in the liquid phase are dissolved in the water molecules.

The ice cubes, being a solid, do not dissolve in the liquid phase but coexist with it in the same container.

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A piece of metal weighing 59.047g was heated to 100°C and then put into a 100mL of water. The metal and water were allowed to come to an equilibrium temperature determined to be 27.8°C. 0.40J/g °C is the  specific heat of the metal.

In thermodynamics, the massic heat capacity (also known as massic heat capacity) of a material is indeed the heat capacity of such a sample of both the material divided by that of the mass of the sample (symbol c).

Informally, it refers to the quantity of heat that needs to be added between one unit of a substance's mass in order to raise its temperature by one unit.

m₁ × c₁×(final temperature-T₁) =-(m₂×c₂×(final temperature-T₂)

59.04 × c₁×(27.8-100) =-(100×4.18×(27.8-23.7)

c₁ =0.40J/g °C

Therefore, 0.40J/g °C is the specific heat of the metal.

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The mass of Fe2S3 formed would be 12.0 g

The limiting reactant is iron (Fe)

The percent yield of iron (III) sulfide would be 108.4%

Fe + S -> FeS

From the equation, we see that one mole of Fe reacts with one mole of S to produce one mole of FeS. To determine the mass of FeS that can be formed, we need to determine which reactant is limiting and which is in excess.

Number of moles of Fe = mass / molar mass = 7.62 g / 55.845 g/mol = 0.136 moles

Number of moles of S = mass / molar mass = 8.67 g / 32.06 g/mol = 0.27 moles

We see that Fe is limiting because there are fewer moles of Fe than S. The stoichiometry of the reaction tells us that one mole of Fe produces one mole of FeS.

The mass of FeS that can be formed is:

mass = number of moles × molar mass

mass = 0.136 moles × 87.91 g/mol (molar mass of FeS)

mass = 12.0 g

percent yield = actual yield / theoretical yield × 100%

percent yield = 13.01 g / 12.0 g × 100%

percent yield = 108.4%

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As a result, the gas's molar mass is 72.05g/mol. If 0.310 grams of a gas are present at the a temperature of 41.4 degrees and a pressure of 951 mm Hg, the molar mass of the gas is 72.05 g/mol.

The amount of a material measured in moles is multiplied either by mass of a chemical compound to get the molar mass M. MB = m/nB, where m is just the total mass of such a sample of a pure substance & nB is the sum of substance B expressed in moles, is the formula for this equation.

A chemical element or compound's molar mass is calculated by dividing its mass (in grams) by the substance's volume (mol). The standard atomic masses of the constituent atoms (in g/mol) can be added to determine the molar mass of a compound.

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The mole ratio of Na₂CO3 to Al₂(CO3)3 can be determined by comparing the coefficients in the balanced chemical equation for the reaction involving these two compounds.

Mole ratio is a term used in chemistry to describe the relationship between the amount of two or more substances in a chemical reaction. It is the ratio of the number of moles of one substance to the number of moles of another substance involved in the reaction.

A mole is a unit of measurement used in chemistry to quantify the amount of a substance. One mole of any substance contains Avogadro's number of particles, which is approximately 6.02 x 10^23 particles. Therefore, a mole ratio describes the relative amounts of substances in terms of the number of moles.

The mole ratio of Na₂CO3 to Al₂(CO3)3 can be determined by comparing the coefficients in the balanced chemical equation for the reaction involving these two compounds.

However, since a reaction is not specified, I can't give you an exact answer.

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Explanation:

Refer to pics.............

According to the molar concentration, if the student needs 250 ml of the diluted solution, 50 ml of the original solution should be used and in second case 0.29 liters of the solution should be used.

Molar concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molar concentration is moles/liter.

The molar concentration depends on change in volume of the solution which is mainly due to thermal expansion. Molar concentration is calculated by the formula, molar concentration=mass/ molar mass ×1/volume of solution in liters.

In terms of moles, it's formula is given as molar concentration= number of moles /volume of solution in liters.Substitution in second  formula gives volume= 0.36/1.25=0.288 liters. and in case of 2 solutions it is calculated as, M₁V₁=M₂V₂ and on substitution gives V₁=0.1×250/0.5=50 ml.

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In the above question regarding metals and conductors, I is false and II is true (option B).

A conductor is a something that can transmit electricity, heat, light or sound.

Metallic elements or solids are excellent conductors of electricity and heat because their atoms form a matrix through which outside electrons can easily move.

Instead of orbiting their individual atoms, they generate a sea of electrons around the positive nuclei of the interacting metal ions.

Therefore, statement I is false while II is true.

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Ce(IO3)3 will not precipitate from the solution.

To determine if Ce(IO3)3 will precipitate from the solution, we need to calculate the concentration of Ce3+ and IO3- ions in the solution, and then use the solubility product constant (Ksp) to determine if a precipitate will form.

First, let's calculate the number of moles of Ce(NO3)3 added to the solution:

nCe(NO3)3 = (750.0 mL) (4.00 x 10^-33 mol/L) = 3.00 x 10^-30 mol Ce(NO3)3

Next, let's calculate the number of moles of KIO3 in the solution:

nKIO3 = (300.0 mL) (2.00 x 10^-2 mol/L) = 6.00 x 10^-3 mol KIO3

Since KIO3 is a strong electrolyte, it will dissociate completely in solution, giving us the same number of moles of IO3- ions:

nIO3- = 6.00 x 10^-3 mol

Since Ce(NO3)3 is also a strong electrolyte, it will dissociate completely to give us 3 times the number of moles of Ce3+ ions:

nCe3+ = 3.00 x 10^-30 mol x 3 = 9.00 x 10^-30 mol

Now, let's calculate the concentration of Ce3+ ions:

[Ce3+] = (9.00 x 10^-30 mol) / (1050.0 mL) = 8.57 x 10^-34 M

Finally, we can calculate the ion product (IP) of Ce(IO3)3:

IP = [Ce3+] [IO3-]^3 = (8.57 x 10^-34)^1 (6.00 x 10^-3)^3 = 7.34 x 10^-41

Comparing this value to the Ksp of Ce(IO3)3 (1.9 × 10^-10), we see that IP << Ksp.

Therefore, Ce(IO3)3 will not precipitate from the solution, and the solution will remain homogeneous.

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The scientist I have chosen is J.J. Thomson, who made significant contributions to the study of atomic structure in the late 19th and early 20th centuries.

Thomson's most well-known contribution is his discovery of the electron, which he identified as a negatively charged particle present in all atoms. This discovery formed the basis of Thomson's "plum pudding" model of the atom, which proposed that atoms consisted of a positively charged "pudding" with negatively charged electrons scattered throughout.

While this model was eventually disproven, Thomson's discovery of the electron and his work on the measurement of atomic and molecular masses laid the foundation for the modern atomic model. Specifically, Thomson's work on mass spectrometry led to the development of more advanced techniques for determining the masses and properties of atoms and molecules, which are still used in modern research today.

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