Which of the following is a cause of eutrophication of a lake? ​

Answer:

[tex]\Delta H\textdegree = -2856.8\;\text{kJ}[/tex] per mole reaction.

[tex]\Delta H\textdegree = -22.3\;\text{kJ}[/tex] per mole reaction.

Explanation:

What is the standard enthalpy of formation [tex]\Delta H_f\textdegree{}[/tex] of a substance? [tex]\Delta H_f\textdegree{}[/tex] the enthalpy change when one mole of the substance is formed from the most stable allotrope of its elements under standard conditions.

Naturally, [tex]\Delta H_f\textdegree{} = 0[/tex] for the most stable allotrope of each element under standard conditions. For example, oxygen [tex]\text{O}_2[/tex] (not ozone [tex]\text{O}_3[/tex]) is the most stable allotrope of oxygen. Also, under STP [tex]\text{O}_2[/tex]  is a gas. Forming [tex]\text{O}_2\;(g)[/tex] from itself does not involve any chemical or physical change. As a result, [tex]\Delta H_f\textdegree{} = 0[/tex] for [tex]\text{O}_2\;(g)[/tex].

Look up standard enthalpy of formation [tex]\Delta H_f\textdegree{}[/tex] data for the rest of the species. In case one or more values are not available from your school, here are the published ones. Note the state symbols of the compounds (water/steam [tex]\text{H}_2\text{O}[/tex] in particular) and the sign of the enthalpy changes.

How to calculate the enthalpy change of a reaction [tex]\Delta H_\text{rxn}[/tex] (or simply [tex]\Delta H[/tex] from enthalpies of formation?

For the first reaction:

Try these steps for the second reaction:

[tex]\Delta H_\text{rxn} = -22.3\;\text{kJ}\cdot\text{mol}^{-1}[/tex].

Answer:

22.94 L.

Explanation:

We can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the gas in atm.

V is the volume of the gas in L.

n is the no. of moles of the gas in mol.

R is the general gas constant,

T is the temperature of the gas in K.

If n and T are constant, and have two different values of V and P:

P₁V₁ = P₂V₂

P₁ = 367.0 mm Hg, V₁ = 49.0 L.

P₂ = 784.0 mm Hg, V₂ = ??? L.

∴ V₂ = P₁V₁/P₂ = (367.0 mm Hg)(49.0 L)/(784.0 mm Hg) = 22.94 L.

Answer:

The correct answer is B

Explanation:

Nuclear Fusion is a raection in which two or more atomic nuclei are combined together to form a heavier nuclei.

The study of chemicals and bonds is called chemistry. The element is made of electrons, protons, and neutrons.

The correct answer is option B that is involves the collision of two nuclei.

The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom.

Fusion means the joining of two-component and according to the question, the correct answer is option B.

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A I believe is correct

Answer:

metal spoon because travels fastest through solid objects

Explanation:

Answer:1. Age of earth 2. D. Newer, Older 3. True

Explanation:

Scientists use rock layers to determine the age of Earth. Fossils in newer, or higher, rock layers are typically younger than those in older or deeper layers. And yes, new evidence can indeed lead to changes in scientific understanding.

1. Scientists use rock layers primarily to determine the age of Earth. They do this through a method called stratigraphy, wherein they study the arrangement of rock layers and relative ages to understand the Earth's past. So, the correct answer is C. The age of Earth.

2. Generally, fossils found in newer layers of rock are estimated to be younger than those found in deeper (or older) layers. As sediment is deposited over time, newer layers form on top of older ones, and as a result, newer fossils are typically found closer to the surface. So the correct answer is B. newer, younger.

3. True. New evidence can definitely lead to a change in scientific knowledge. Science is a dynamic and evolving field and new discoveries or data can modify or even completely change previously held theories and understandings.

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72.71 . simple google search, you shouldnt waste points

For this case we have the [tex]CO_ {2}[/tex]

It is composed of one atom of carbon and two of oxygen.

The atomic mass of carbon and oxygen, which can be found in a periodic table, are given by:

[tex]C: 12 \frac {g} {mol}\\O: 16 \frac {g} {mol}[/tex]

Then, we find the atomic mass of [tex]CO_{2}[/tex]:

[tex]1 * 12 \frac {g} {mol} = 12 \frac {g} {mol}\\2 * 16 \frac {g} {mol} = 32 \frac {g} {mol}[/tex]

Adding we have:

[tex]44 \frac {g} {mol}[/tex]

To find the percentage of oxygen, we divide the atomic mass of the two oxygen atoms between that of [tex]CO_{2}:[/tex]

[tex]\frac {32} {44} * 100 = 72.73[/tex]%

Thus, the percentage of oxygen is 72.73%

Answer:

72.73%

Answer:

471 g

Explanation:

When 8.73 moles of benzene react with excess oxygen, approximately 471.42 grams of water will be produced.

In order to find out how many grams of water are produced from the reaction of 8.73 moles of benzene (C6H6) with excess oxygen (O2), we need to know the balanced chemical reaction. The combustion reaction for benzene looks like this:

C6H6 + 7.5O2 -> 6CO2 + 3H2O

From the balanced combustion reaction, it can be seen that for each mole of benzene reacting, 3 moles of water are produced. So, if 8.73 moles of benzene react, it would yield 3 times this many moles of water: 8.73*3 = 26.19 moles of water.

As the molar mass of water (H2O) is approximately 18 g/mole, we can calculate grams of water by multiplying moles of water and molar mass of water.

26.19 moles * 18 g/mole = 471.42 grams of water

So, approx 471.42 grams of water can be produced when 8.73 moles of benzene react with excess oxygen.

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Solution:

Density of iron( d)=?

Specific gravity of iron=7.87

Density of water at 4°C=1g/cm^3

we have,

specific gravity =density of object/density of water at 4°C

or,7.87=d/1

or, d=7.87g/cm^3

Again,

density=mass/ volume

or,7.87=7/V

or,V=7/7.87

or,V=0.88cm^3

therefore, volume occupied by iron is 0.88cm^3

Answer:

Cr

Mn⁺¹

Fe⁺²

Explanation:

Answer:

CaF₂+H₂SO₄ → CaSO₄+2HF     ΔH = +157.7KJ

Explanation:

Energy changes in chemical reactions is one of the most important issues in thermodynamics  especially the enthalpy of reaction (ΔHrxn)

           CaF₂+H₂SO₄+157.7KJ → CaSO₄+2HF

which can be expressed in alternate form as following

CaF₂+H₂SO₄ → CaSO₄+2HF     ΔH = +157.7KJ

Answer:

3.8 liters

Explanation:

According to Avogadro’s Law  of gases

at constant temperature and pressure, the volume of all gases constitutes an equal number of molecules. In other words, the volume of any gas is directly proportional to the number of molecules of that gas.

∴ V ∝ n   or (V₁/V₂) = (n₁/n₂)

V₁= 2.5 L

n₁= 0.3 mol

n₂= 0.3 mol + 0.15 mol = 0.45 mol

using cross multiplication

(2.5 L / V₂) = (0.3 mol / 0.45 mol)

V₂= 3.8 L

∴ The right choice is 3.8 liters

Answer:

3.8 liters

Explanation:

Answer:hi guys it is both objects are the same temperature

Explanation:

Heat transfers from a warmer object to a colder one (such as an ice cube) until both objects are at the same temperature. This is a process known as conduction.

When an ice cube is placed on an object that is warmer than it, heat will be transferred from the warmer substance to the ice cube. This process will continue until both objects are the same temperature. This is explained by the physics law of heat transfer, specifically conduction, which is the process where heat energy is transferred between substances in direct contact with each other.

The warmer object will lose heat to the colder object (the ice cube) until equilibrium is reached and both objects have the same temperature. It may also coincide with other options like the ice melting or ice reaching 0°C, but this depends on the initial temperature of the warmer object.

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Answer:

When substances combine to form new substances, the properties of the reactants are preserved.

Explanation:

When the two elements Na and Cl combine, they produce a stable, crystalline solid known commonly as table salt.  This explains as when substances combine to form new substances, the properties of the reactants are preserved. Therefore, option A is correct.

Elements are pure substances that cannot be broken down into simpler substances by chemical means. They are made up of atoms, which have a specific number of protons in their nucleus that defines their atomic number.

In a chemical reaction, the atoms that form the first substances are regrouped into other molecules, and these new substances have various properties from those of the reactants. The total number of all types of atoms is kept, and thus the mass does not change.

Thus, option A is correct.

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lowest melting point-covalent solids

highest melting point-ionic solids

Molecular solids like ice tend to have lower melting points due to weaker intermolecular forces, while ionic solids such as sodium chloride have high melting points due to strong ionic bonds. Network covalent solids also have high melting points, whereas amorphous solids soften over a range of temperatures.

The melting point of a solid is the temperature at which the solid changes into a liquid. It reflects how much kinetic energy is required for the particles within a solid to overcome the attractive forces keeping them in place. In general, molecular solids, such as ice (melting point of 0°C), tend to have lower melting points due to weaker intermolecular forces like hydrogen bonds or London dispersion forces. On the other hand, ionic solids, such as sodium chloride (melting point of 801°C), display the highest melting points because the ionic bonds between their ions are very strong.

Network covalent solids often have high melting points as well since the atoms within the network are bonded by covalent bonds that require significant energy to break. By contrast, amorphous solids like butter do not have a sharp melting point but rather soften over a range of temperatures due to the lack of a well-ordered molecular structure like that seen in crystalline solids.

Answer is A Access pictures of the area taken by satelites.

Explanation: Satelites are the only thing out of these four answers that does not requir power supply from the town. Hope it helped!

The newspaper can get the pictures of the place by accessing pictures of the area taken by satellites.

Satellites use magnetic sensors to collect electromagnetic radiation of specific wavelength reflected from the Earth surface.

These sensors are able to detect wavelengths that are not possible by human eyes.

The power supply that has been cut off does not affect the satellite, hence it will detect the waves reflected from the Earth surface during the hurricane and the photo of the place can used by the newspaper for its morning edition.

Thus, the best way for the newspaper to get the pictures of the place is to access pictures of the area taken by satellites.

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Answer:

34.44 g.

Explanation:

Fe + S → FeS,

It is clear that 1.0 mol of Fe reacts with 1.0 mol of S to produce 1.0 mol FeS.

no. of moles of Fe = mass/atomic mass = (60.0 g)/(55.845 g/mol) = 1.074 mol.

no. of moles of FeS = mass/molar mass = (90.0 g)/(87.91 g/mol) = 1.024 mol.

∵ Fe reacts with S with (1: 1) molar ratio.

∴ The no. of moles of S needed to react with Fe is 1.074 mol.

∴ The no. of grams of S needed = no. of moles x molar mass = (1.074 mol)(32.065 g/mol) = 34.44 g.

Answer:

The answer is:

A. 30 grams

Explanation:

Answer:

- 0.0413°C ≅ - 0.041°C (nearest thousands).

Explanation:

ΔTf = Kf.m,

Where,

ΔTf is the change in the freezing point.

Kf is the freezing point depression constant (Kf = 1.86 °C/m).

m is the molality of the solution.

Molality is the no. of moles of solute per kg of the solution.

∴ molality (m) = no. of moles of solute/kg of solvent = (0.04685 mol)/(2.11 kg) = 0.0222 m.

∴ ΔTf = Kf.m = (1.86 °C/m)(0.0222 m) = 0.0413°C.

∴ The freezing point of the solution = the freezing point of water - ΔTf = 0.0°C - 0.0413°C = - 0.0413°C ≅ - 0.041°C (nearest thousands).

Answer:

-0.041

Explanation:

Answer:

The last choice is oxidation.

Explanation:

The this is a reaction in which the oxidation number of chromium metal

( 0 ) goes the an oxidation number of 3 in Cr3+.

Answer : The correct option is, [tex]Cr(s)\rightarrow Cr^{3+}(aq)+3e^-[/tex]

Explanation :

Redox reaction : It is a reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is a reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Reduction reaction : It is a reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

The correct oxidation-half reaction will be :

[tex]Cr(s)\rightarrow Cr^{3+}(aq)+3e^-[/tex]

In this half oxidation reaction, the oxidation state of 'Cr' changes from (0) to (+3) that means the oxidation state increases that means it shows oxidation.

Answer:

D. Catalysts speed up the rate of reactions by lowering the amount of energy required for the reaction to proceed.

Explanation:

A catalyst is a substance that:

A catalyst provides an alternative reaction pathway that has a lower activation energy than the uncatalyzed reaction.

The figure shows how the energy of the reactants and products change during a reaction.

Answer:

[tex]\boxed{\text{311 K}}[/tex]

Explanation:

We can use the Ideal Gas Law and solve for T.

pV = nRT

Data:  

p = 0.998 atm

V = 1.20 L

n = 0.0470 mol

R = 0.082 06 L·atm·K⁻¹mol⁻¹

Calculation:

0.998 × 1.20 = 0.0470 × 0.082 06 × T

1.198 = 0.003 857T

[tex]T = \dfrac{1.198}{0.003 857} = \textbf{311 K}[/tex]

The Kelvin temperature is [tex]\boxed{\textbf{311 K}}[/tex], not 307 K.

I suppose you could choose the last square, as it has the closest value.

you can find the run by subtracting the X coordinate of the left point from that of the right point

You can find by subtracting the variable

Answer:

Hydrogen sulfide is nonpolar. Even though the molecular geometry would allow for it to polar, the bonds are not polar, so the molecule isn't either. Polarity is determined by electronegativity.

[tex]H_2S[/tex] is a polar substance.

Polar particles form when two molecules don't share electrons similarly in a covalent bond. This happens when there is a distinction between the electronegativity of every molecule. An extraordinary distinction shapes an ionic bond, while a lesser contrast frames a polar covalent bond.  

If the electronegativity between the two ions is somewhere in the range of 0.5 and 2.0, the structure of the particle forms a polar covalent bond. In the event that the electronegativity distinction between the ions is more than 2.0, the bond is ionic. Ionic mixes are amazingly polar particles.  

Instances of polar particles include:  

Answer:

The theoretical yield of copper is approximately 1.65 grams.

Explanation:

Relative atomic mass data from a modern periodic table:

As a metal, aluminum is more reactive than copper. Aluminum will reduce the [tex]\text{Cu}^{2+}[/tex] ion in [tex]\text{CuCl}_2\;(aq)[/tex] to [tex]\text{Cu}\;(s)[/tex]. This process will form a positive aluminum ion, which will then combine with chloride ions in the solution. What will be the charge on each aluminum ion? Aluminum is in IUPAC Group 13 of the periodic table. Each aluminum atom contains three valence electrons. As a main group metal in the p-block, each atom will lose all three of its valence electrons to form [tex]\text{Al}^{3+}[/tex] ions with three positive charges. Each ion will combine with three [tex]\text{Cl}^{-}[/tex] ions to produce a species with the empirical formula [tex]\text{Al}\text{Cl}_3[/tex].

Reactants:

Products:

Let the coefficient in front of [tex]\text{AlCl}_3\;(aq)[/tex] be [tex]1[/tex].

[tex]\begin{array}{cccccccl}\text{Al}\;(s) & +& \text{CuCl}_2\;(aq) & \to & \text{AlCl}_3\;(aq) & + & \text{Cu}\;(s)\\ & & & & {\bf 1} & & &\begin{aligned}&\text{Assign "1" to the most}\\[-0.5em]&\text{complex compound.}\end{aligned} \\ {\bf 1}& &{\bf 3/2} & & 1 & & &\begin{aligned}&\text{Al and Cl atoms}\\[-0.5em]&\text{conserve.}\end{aligned}\end{array}[/tex][tex]\begin{array}{cccccccl}\phantom{\;\text{Al}\;(s)} & \phantom{+}& \phantom{\text{CuCl}_2\;(aq)} & \phantom{\to} & \phantom{\text{AlCl}_3\;(aq)} & \phantom{+} & \phantom{\text{Cu}\;(s)}\\[-1em]1& &{3/2} & & 1 & & {\bf 3/2} &\begin{aligned}&\text{Cu atoms shall also}\\[-0.5em]&\text{conserve.}\end{aligned} \\2& &{3} & & 2 & & {3} &\begin{aligned}&\text{Multiply all}\\[-0.5em]&\text{coefficients by two}\\[-0.5em]&\text{to eliminate fractions.}\end{aligned}\end{array}[/tex].

Hence the balanced equation:

[tex]2 \;\text{Al} \;(s) + 3 \;\text{CuCl}_2\;(aq) \to 2\;\text{AlCl}_3\;(aq) + 3\;\text{Cu}\;(s)[/tex].

Assume that [tex]\text{CuCl}_2[/tex] is the limiting reactant.

Formula mass of [tex]\text{CuCl}_2[/tex]:

[tex]M(\text{CuCl}_2) = 63.546 + 2 \times 35.45 = 134.446\;\text{g}\cdot\text{mol}^{-1}[/tex].

Number of moles of [tex]\text{CuCl}_2[/tex] available:

[tex]\displaystyle n = \frac{m}{M} = \frac{3.5}{134.446} = 0.0260328\;\text{mol}[/tex].

The ratio between the coefficient in front of [tex]\text{CuCl}_2[/tex] is the same as the coefficient in front of [tex]\text{Cu}[/tex].

[tex]\displaystyle \frac{n(\text{Cu})}{n(\text{CuCl}_2)} = \frac{\text{Coefficient in front of } n(\text{Cu})}{\text{Coefficient in front of } n(\text{CuCl}_2)} = \frac{3}{3} = 1[/tex].

[tex]n(\text{Cu}) = 1 \cdot n(\text{CuCl}_2) = 0.0260328\;\text{mol}[/tex].

Mass of copper that is expected to be produced if [tex]\text{CuCl}_2[/tex] is the limiting reactant:

[tex]m(\text{Cu}) = n(\text{Cu}) \cdot M(\text{Cu}) = 0.0260328 \times 63.546 =1.65\;\text{g}[/tex].

Assume that [tex]\text{Al}[/tex] is the limiting reactant.

The methods are similar. Try the steps above yourself.

Formula mass of [tex]\text{Al}[/tex]:

[tex]M(\text{CuCl}_2) = 26.982\;\text{g}\cdot\text{mol}^{-1}[/tex].

Number of moles of [tex]\text{Al}[/tex] available:

[tex]\displaystyle n = \frac{m}{M} = \frac{0.5}{26.982} = 0.0185\;\text{mol}[/tex].

The ratio between the coefficient in front of [tex]\text{CuCl}_2[/tex] is [tex]3/2[/tex] times the coefficient in front of [tex]\text{Al}[/tex].

[tex]\displaystyle \frac{n(\text{Cu})}{n(\text{Al})} = \frac{\text{Coefficient in front of } n(\text{Cu})}{\text{Coefficient in front of } n(\text{Al})} = \frac{3}{2}[/tex].

[tex]\displaystyle n(\text{Cu}) = \frac{3}{2} \cdot n(\text{Al}) = 0.0277963\;\text{mol}[/tex].

Mass of copper that is expected to be produced if [tex]\text{Al}[/tex] is the limiting reactant:

[tex]m(\text{Cu}) = n(\text{Cu}) \cdot M(\text{Cu}) = 0.0277963 \times 63.546 =1.77\;\text{g}[/tex].

[tex]1.65\;\text{g} < 1.77\;\text{g}[/tex]. The first assumption is valid. [tex]\text{CuCl}_2[/tex] will run out before all [tex]0.5\;\text{g}[/tex] of aluminum are consumed, Only [tex]1.65\;\text{g}[/tex] of copper will be produced.

Air, soil, plants, fuels and water are examples of natural resources. Some of these (ex. air & water) are renewable. Some however are nonrenewable (ex. fuels). If not conserved and protected, we may lose some of these resources to pollution or depletion.

The Earth's natural resources include air, water, soil, minerals, fuels, plants, and animals. Conservation is the practice of caring for these resourcesso all living things can benefit from them now and in the future. ... These are renewable resources. Otherresources, such as fossil fuels, cannot be replaced at all.

Source: National Geography

Answer:

Graphics can sometimes convey more information in a brief amount of space than an author can explain in a paragraph.

The average rate of the reaction over the first 580 seconds is approximately [tex]2.07 \times 10^{(-3)} M/s[/tex]. Thus, option C is correct.

To find the average rate of the reaction over the first 580 seconds, we can use the formula:

[tex]\[ \text{Average rate} = \frac{\text{Change in concentration}}{\text{Change in time}} \][/tex]

Given the concentrations at 0 s and 580 s, and the corresponding times, we can calculate the change in concentration and change in time:

Change in concentration = 1.8 M - 0.6 M = 1.2 M

Change in time = 580 s - 0 s = 580 s

Now, we can calculate the average rate:

Average rate = [tex]\(\frac{1.2 \text{ M}}{580 \text{ s}}\)[/tex]

Average rate = [tex]\(2.07 \times 10^{-3}\) M/s[/tex]

Therefore, the average rate of the reaction over the first 580 seconds is approximately [tex]2.07 \times 10^{(-3)} M/s[/tex]. Since this is closest to option C [tex](2.0 \times 10^{(-3)})[/tex], the answer is C.

Answer:

[tex]\boxed{\text{417 kJ}}[/tex]

Explanation:

There are three heat transfers in this process:

Total heat = warming the ice + melting the ice + warming the water  

       q        =           q₁               +           q₂             +              q₃

       q        =       mC₁ΔT₁          +        mΔHfus       +          mC₂ΔT₂

Let's calculate these heat transfers separately.

Data:

      m = 1 kg = 1000 g

     C₁ = 2.108 J·°C⁻¹g⁻¹

     C₂ = 4.184 J·°C⁻¹g⁻¹

ΔHfus = 333 J/g

Tmax =   15 °C

 m.p. =    0 °C

Tmin = -10 °C

Calculations:

ΔT₁ = 0 – (-10) = 10 °C

q₁ = 1000 × 2.108 × 10 = 21 080J = 21.08 kJ

q₂ = 1000 × 333 = 333 000 J =333 kJ

ΔT₂ = 15 - 0 = 15 °C

 q₃ = 1000 × 4.184 × 15 = 62 760 J = 62.76 kJ

q = 21.08 + 333 + 62.76 = 417 kJ

You must add [tex]\boxed{\textbf{417 kJ}}[/tex].

Answer:

9.0 g/cm³

Explanation:

Density can be computed with the formula:

[tex]D=\dfrac{M}{V}[/tex]

Where:

D = Density

M = Mass

V = Volume

In your problem we are given:

84 cm³ = volume

760 g = mass

So we just plug in our given into the formula:

[tex]D=\dfrac{M}{V}[/tex]

[tex]D=\dfrac{760g}{84cm^{3}}[/tex]

[tex]D=9.05g/cm^{3}[/tex]

The answer would then be:

9.0 g/cm³

Answer:

it is 9.04 or 9.0

Explanation:

Volume is a measurement if the amount of space an object occupies.

Answer:

He is determining physical properties that are sufficient to identify the metal.

Explanation:

So, the right choice is:

He is determining physical properties that are sufficient to identify the metal.

A! He is determining physical that are sufficient to identify the metal.