how cells in unicellular and multicellular organisms perform the tasks needed for life.

The net change in enthalpy for the formation of one mole of lead(ii) sulfate from lead, lead(iv) oxide, and sulfuric acid is -274.5 KJ,

Calculation

Reaction 1: [tex]H_{2} SO_{4(aq)}--- > SO_{3(g)} +H_{2} O_{(l)}[/tex] ,  Δ[tex]H^{Q} = +113 KJ[/tex]

Reaction 2: [tex]Pb_{(s)} +PbO_{2(s)} +2SO_{3(s)} --- > 2PbSO_{4(aq)}[/tex] Δ[tex]H^{Q} =-775 KJ[/tex]

To calculate the net change in enthalpy for the formation of 1 mole of [tex]PbSO_{4(aq)}[/tex]

Divide reaction 2 by  2

⇒[tex]\frac{Pb_{(s)}}{2} +\frac{PbO_{2(s)}}{2} +\frac{2SO_{3(s)}}{2} --- > \frac{2PbSO_{4(aq)}}{2}[/tex],  Δ[tex]H^{Q} =\frac{-775}{2} KJ[/tex]

⇒[tex]\frac{Pb_{(s)}}{2} +\frac{PbO_{2(s)}}{2} +SO_{3(s) --- > PbSO_{4(aq)[/tex] , Δ[tex]H^{Q} =-387.5 KJ[/tex]

Subtract reaction 1 with the above reaction

[tex]H_{2} SO_{4(aq)}--- > SO_{3(g)} +H_{2} O_{(l)}-\frac{Pb_{(s)}}{2} +\frac{PbO_{2(s)}}{2} +SO_{3(s) --- > PbSO_{4(aq)[/tex]

⇒[tex]H_{2} SO_{4(aq)}+\frac{Pb_{(s)}}{2}+\frac{PbO_{2(s)}}{2} --- > PbSO_{4(aq)}+H_{2} O_{(l)}[/tex]

Δ[tex]H^{Q}[/tex]=Δ[tex]H^{Q} Product[/tex]+Δ[tex]H^{Q} Rreactant= -387.5 KJ+113 KJ[/tex]

Δ[tex]H_{formation} =-274.5 KJ[/tex]

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The atomic mass of every element may be simply calculated using the number of protons and neutrons in the nucleus.

The atomic mass can be approximated by summing the number of protons and neutrons in the atom. The average mass of an element's atoms that are meaningfully measured in the atomic mass unit (amu) is defined as its atomic mass. It should be noted that the atomic mass is calculated by adding the masses of all the element's isotopes. This is the most precise method for calculating the relative atomic mass.

However, if we do not wish to compute the precise atomic mass of one of the elements, we may simply sum the number of protons and neutrons in the atom. This provides us a ballpark estimation of the atom's mass. Another way for estimating the atomic mass of any element is to simply double the value of the atomic number that is known for each individual element.

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Calculation of percent yield requires the theoretical yield to be calculated first. Using that method, the percent yield of the reaction is 44%.

To calculate the percent yield of calcium nitride, we first need to calculate the theoretical yield. To do this, we need the molar mass of both calcium (40 g/mol) and calcium nitride (3 * 40 + 2 * 14) g/mol = 148 g/mol.

3 moles of calcium produce 1 mol of calcium nitride so the proportion we can make will look like this:

120 g of calcium : 148 g of calcium nitride = 56.6 g of calcium : X

X = 148 g of calcium nitride * 56.6 g of calcium / 120 g of calcium

X = 69.8 g of calcium nitride

This is the theoretical yield. Calculating the percent yield works like this - we divide the actual mass by the theoretical yield and then multiply that number (that is always supposed to be between 0 and 1) by 100%:

%yield = 100% * 31.0 g / 69.8 g = 44%

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It takes 5.89 x 10¹⁰ Oreos to reach the moon.

The average distance from the Earth to the moon is 385 000.6 km.

Metres = 385 000.6 km × (1000 m/1 km ) = 385 000 600 m

Centimetres = 38 500 060 000 m × (100 cm/1 m) = 38 500 060 000 cm

Oreos = 38 500 060 000 cm × (1 Oreo/0.654 cm) = 58 900 000 000 Oreos

= 5.89 x 10¹⁰ Oreos

Its diameter is around one-quarter that of the Earth (comparable to the width of Australia). The Moon is the Solar System's fifth-largest satellite. It is the largest (and most massive) satellite relative to its home planet and is larger than any other known dwarf planet. [f] According to geophysical criteria, the Moon is a planetary-mass object that became a differentiated rocky body, making it a satellite planet. There is no atmosphere, hydrosphere, or magnetic field. Its surface gravity is around one-sixth that of Earth (0.1654 g). Io, Jupiter's moon, has the highest surface gravity and density of any satellite in the Solar System.

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Answer:

Atomic Size Trend Across the Period

This is caused by the increase in the number of protons and electrons across a period. One proton has a greater effect than one electron cause of the coulombic law. Thus, electrons are pulled towards the nucleus, resulting in a smaller radius.

Explanation:

Continental drift is a geologic process that forms channel on Mars.

Continental drift, the same process that creates contemporary channels like the mid-Atlantic channel or the African Rift Valley, is the geologic process that is most likely to have created the channel on Mars. Massive troughs that are visible from orbit are being exposed when Mars' tectonic plates separate. Similar to Earth, Mars too experiences gradual continental drift, which moves by less than an inch per year and is much too slow for any person to notice. However, this can lead to significant geological and geographic changes over millions of years that modify the planet's surface.

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The average atomic mass of the given isotopes of Halfnium is 178.55 amu

The average atomic mass of an element is equal to the sum of its isotope masses multiplied by it's own natural abundance (the decimal associated with the percent of atoms of that element for a given isotope).

In order to determine the weighted average, we must consider the % natural abundances of each isotope. The atomic mass of an element is the weighted average of the atomic masses of the element's naturally occurring isotopes. Determine the average atomic mass by using atomic masses and percentage abundances of each isotope. To convert each percentage abundance to decimal form, divide it by 100. Multiply this figure by the atomic mass of the isotope. To get the average atomic mass, add the atomic masses of each isotope together.

To determine the average atomic mass of Halfnium, the mass fractions of the isotopes multiplied by their respected atomic masses must all be added.

Using 100 atoms as the basis, calculate the mass fractions (m1, m2,...m5):

m1 =   5/100 = 0.05

m2 = 19/100 = 0.19

m3 = 27/100 = 0.27

m4 = 14/100 = 0.14

m5 = 35/100 = 0.35

Multiplying the mass fractions with the atomic masses of the respective isotopes.

Average atomic mass of Halfnium is:

Avg = (m1 x 176) + (m2 x 177) + (m3 x 178) + (m4 x 179) + (m5 x 180)

Avg = (0.05 x 176) + (0.19 x 177) + (0.27 x 178) + (0.14 x 179) + (0.35 x 180)

Avg = 178.55 amu

Therefore, the average atomic mass of Halfnium based on the data for its given isotopes is 178.55 amu.

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The enthalpy of precipitation of calcium fluoride is -13.974 kJ/mol.

In order to solve this, first we need to write the balanced chemical reaction equation of the reaction in question:

CaCl₂(aq) + 2KF(aq) → CaF₂(s) + 2KCl(aq)

In order to calculate the enthalpy of precipitation (ΔH), we need the amount  of heat released (Q) and the number of moles of CaF₂ (n):

ΔH = Q/n

To calculate the number of moles, we can use the molarity (c = 1.00 M) of the calcium chloride solution and its volume (V = 25 mL = 0.025 L):

c = n/V ⇒ n = c*V

n = 1.00 M * 0.025 L = 0.025 mol

We calculate the amount of heat released (Q) using the following equation:

Q = (t₁ - t₂) * C * m

t₁ - initial temperature (25.0 ⁰C)

t₂ - final temperature (26.7 ⁰C)

C - specific heat capacity (4.184 J/⁰Cg)

m - the mass of the solution

We need the mass of the solution, which we can calculate using the density (d = 1.00 g/mL) and the volume (V = 25 mL + 25 mL = 50 mL) of the solution:

d = m/V ⇒ m = d*V

m = 1.00 g/mL * 50 mL = 50 g

Q = (25.0 ⁰C - 26.7 ⁰C) * 4.184 J/°Cg * 50 g

Q = -349.4 J

ΔH = -349.4 J / 0.025 mol

ΔH = -13974 J/mol = -13.974 kJ/mol

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In a polypeptide chain, to generate an amide, the peptide bond connects the carboxyl group of one amino acid (x) to the amino group of the subsequent amino acid (y).

A polypeptide chain is defined as a series of amino acids linked together by peptide bonds. Poly stands for numerous, while peptide stands for protein. A polypeptide chain is therefore a chain of protein or amino acid building components. Polypeptide chains are crucial because they are the building blocks of proteins.

The carboxyl group of the first amino acid, w binds with the amino group of the next amino acid, x. The carboxyl group of x binds with the amino group of the y amino acid. Thus, peptide bonds are formed between the w-x-y amino acids making them a polypeptide chain.

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The number of milliliters of 3.0m NaOH required to react with 0.5g of Cu2+ to form Cu(OH)2 is 5.249 ml

The reaction is as follows;

2NaOH  + Cu2+  ------------> Cu(OH)2  +  2Na+

From the balanced chemical reaction, 0.5 g of Cu2+ = 0.5/63.5 = 7.874x10-3 moles  (molar mass of Cu2+ = 63.5 g)

Thus, moles of NaOH required = 2*moles of Cu2+ = 0.01575

Now, moles of NaOH = molarityxvolume in litres

or,  3*volume in litres = 0.01575

or, volume in litres  = 5.249*10-3 litres = 5.249 ml

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Answer: Hormones are are the body's chemical messengers, sending signals into the bloodstream and tissues. Hormones work slowly, over time, and affect many different processes, including growth and development, metabolism – how your body gets energy from the foods you eat- sexual function, reproduction, and mood

Light energy is used in photosynthesis to convert carbon dioxide and water into glucose and oxygen. 1 glucose molecule and 6 oxygen molecules are produced for every 6 carbon dioxide and 6 water molecules.

C₆H₁₂O₆ is the chemical formula for glucose, a simple sugar. When a glucose molecule is assembled during photosynthesis, it absorbs 12 hydrogen ions from the chloroplast stroma. Reactants in photosynthesis include oxygen, carbon dioxide, ATP, and NADPH. Water and GA3P are both products. Chlorophyll, water, and carbon dioxide are reactants in photosynthesis. When the process is finished, photosynthesis produces oxygen and carbohydrate molecules, most commonly glucose. These sugar molecules contain the energy required by living things to survive.

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Get the fire blanket and notify the teacher.

If your clothing catches fire do not run or do anything else to fan the flames. Immediately drop it on the ground and roll it to extinguish the flames. The laboratory is also equipped with fire blankets to extinguish clothing fires. Used by instructors as needed to completely extinguish flames.

Long hair should be tied up and long sleeves should not be worn. Always keep hair clothing, and hands at a safe distance from flames. Never touch the open flame with your hands. Use tongs when holding objects in flames. Long hair can fall on lab benches or come into contact with chemical or biological agents.

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Answer:0.74

Explanation:0.74

14.67KJ is the number of joules given off when 32.0 grams of steam cools from 110.0 C to ice at -40.0 C.

The vibrations of molecules or atoms increase when a body's temperature rises. From one area of the body to another, these vibrations are then transmitted. The amount of energy that a system's molecules vibrate with is referred to as its stored heat.

According to the definition of heat, it is the movement of energy from a warm item to a cooler one. The flow of heat energy is in the direction of moving from a substance with a higher temperature to one with a lower temperature.

q =mcΔT

    =32.0×4.18×(110-40)

    = 14.67KJ

Therefore, 14.67KJ is the number of joules given off when 32.0 grams of steam cools from 110.0 C to ice at -40.0 C.

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The molar concentration of HCl in the original solution is 0.19

The balanced chemical equation for the reaction must be our starting point because it will provide us with the reactants' mole ratios and allow us to answer this question.

* NaOH + HCl --> NaCl + H2O

this means:

1 mole NaOH reacts with 1 mole HCl

thus the ratio of NaOH to HCl is 1: 1

Next we've got to calculate the moles of NaOH: (molecular Mass = 40 g/mol)

moles(NaOH) = 3.76g/40

= 0.094 moles

Now we can calculate the concentration of NaOH:

Note: 361mL/1000 = 0.361L

conc(NaOH) = 0.094 moles/0.361L

= 0.26 mol/L

Now the mole ratio of NaOH to HCl is 1:1

But we have used only 0.094 moles so since the ratio of NaOH to HCl is 1:1, it means that 0.094moles of NaOH can only react with 0.094 moles of HCl.

Note: 491mL/1000mL = 0.491L

conc(HCl) = 0.094 moles/0.491L

= 0.19 mol/L

Thus the molar concentration of HCl in the original solution is 0.19

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If ammonia is added to the system, the reaction will shift to the right, in favour of the forward direction.

A reaction is said to be at equilibrium when the concentration of reactants is equal to the concentration of the products. This means that the rate at which reactants are forming products is equal to the rate at which products are changed back to reactants.

All reactions at equilibrium follow Le Chatelier's principle, which states that if a chemical system in equilibrium is disturbed by changing the conditions (such as concentration, temperature and pressure changes), the position of equilibrium shifts to the left or to the right in order to counteract the change and to re-establish an equilibrium.

This means that if certain factors in a chemical reaction at equilibrium is changed, the reaction will shift either to the left or to the right. If it shifts to the left, the backward reaction is favoured and more reactants are produces, but if it shifts to the right, the forward reaction is favoured, and more products are produced.

In the question above, ammonia (2NH₃) is added to the chemical system. This will cause an increase in the concentration of ammonia; hence, more ammonia will be converted to nitrogen and hydrogen in order to decrease the concentration of ammonia and re-establish equilibrium. This causes the reaction to shift to the right.

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In this question, we need to find the value of pressure of a 15 grams sample of CO2 gas, and in order to find this value, we will be using the Ideal gas law formula, which is the following:

PV = nRT

Where:

P = pressure in atm

V = volume in liters, 20 Liters

n = number of moles

R = gas constant, 0.082

T = temperature in kelvin, 0°C = 273 K

The number of moles we need to find based on the mass in the question and based on the molar mass of CO2, 44g/mol:

44g = 1 mol

15g = x moles

44x = 15

x = 15/44

x = 0.34 moles of CO2 in 15 grams

Now we have the values to add to the formula:

P * 20 = 0.34 * 0.082 * 273

20P = 7.61

P = 7.61/20

P = 0.38 atm of pressure

The pressure will be 0.38 atm

Answer:

128

Explanation:

Iron has atomic number of 53

so mass number is 53 + 75 = 128

Chemical compounds are created when elements combine and are frequently separated into two groups. Ionic compounds are frequently created when metals and nonmetals react.

These substances are made of neutral atoms and molecules that have had their electrons added to or taken away to generate positive and negative ions.

The mantle and the solid inner core are separated by this layer of the planet. It is the sole liquid layer, a 1,400 mile sea made largely of iron and nickel. Iron and nickel make up the majority of the lava. The magnetic field of the Earth is produced by the outer core. The inner core, which is the last layer, is 900 miles deep. According to scientists, the inner core is a solid ball of minerals and iron.

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The molarity of a solution is 3.743M.

Molarity of a solution:

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

The formula for the molarity of a solution:

M = [tex]w_{B}[/tex] × 1000 / [tex]M_{B}[/tex] × V(ml)

[tex]w_{B}[/tex] = 50.54g

[tex]M_{B}[/tex] = molecular mass of water(H2O) = 2 + 16 = 18

V = Volume = 750ml

Putting the value in the equation, we get

M = 50.54 ×1000 / 18 × 750

   = 50540 / 13500

    = 3.743M

Therefore the molarity of a solution is 3.743M

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The group with a better result is group 1

Three ways that the groups could improve their results in terms of the crystallization experiment and the melting point investigation are: recrystallisation, elimination of impurity, and heating the solvent.

Group 1's result is better, it is so because they have got the melting point range in a close proximity, that means they do not have a broad range. Smaller the range of melting point, more accurate the compound is synthesized.

3 ways that the groups could improve their results:

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Yes, there are chemical reactions that are brought about through the use of light (such as free radical halogenation) and there are chemical reactions that produce light (chemiluminescence).

Numerous reactions use light as an initiator. For example, in various examples of free radical halogenation (a reaction between a hydrocarbon and a halogen molecule, where alkyl halides are formed), light is needed to break the bond between the bromine atoms in order to form bromine radicals that then initiate the chain reaction leading to the formation of the product.

The phenomenon of producing light through a chemical reaction is called chemiluminescence. It is relatively rare, but not unheard of. One example is the reaction between luminol and hydrogen peroxide, which forms 3-aminophthalate and releases light.

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All of the nitrogen in the N2H4 molecule hybridizes to Sp3.

The combining of two atomic orbitals to create a whole new class of hybridized orbitals is the notion of hybridization in chemistry. Hybrid orbitals with completely distinct energies are often the outcome of this mixing. In hybridization, the same-energy level atomic orbitals are crucial. However, as long as they have an equivalent amount of energy, both fully and partially filled orbitals can participate in this process.

All of the nitrogen in the N2H4 molecule hybridizes to Sp3. N2H4 has a dipole moment of 1.85 D and is polar in nature. The nitrogen atoms in N2H4 have no formal charge. The N2H4 molecule has a trigonal molecular geometry (shape).

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Likely the foremost recognizable impact of soil disintegration is land degradation.

Asia-Pacific region is an area of extreme soil degradation.

Likely the foremost recognizable impact of soil disintegration is land debasement. As disintegration wears down the soil and its arrival, its capacity to bolster plant life diminishes.

Around the globe, soil disintegration is happening at a speedier rate than it can regenerate. When arrival corrupts, it annihilates territories and diminishes the sum of arrival accessible for agricultural needs or the requirements of natural life.

Since of land degradation, the soil cannot back plant life. Plants require solid, nutrient-filled soil to develop and deliver. In case the ground isn’t able to back vegetation, you won’t be able to develop nourishment.

Other than that, with fewer plants accessible to sequester carbon dioxide from the environment, the rate of climate alters increments. Increasingly carbon dioxide is cleared out within the climate, which is causing harm to the environment.

It increments the earth’s normal temperature and modifies precipitation, both of which can advance the progress of desertification.

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This chemical equation is balanced.

What is chemical equation?

chemical equation are symbolic representation of chemical reactions in which the reactants and the product are expressed in term of their respective chemical formula.

Reactants are converted to products and the process is symbolise by a chemical equation.

Sol-

NH^3+O^2------>NO+H^2O

2NH^3+O^2----->2NO+3H^2O

2NH^3+O^2------>2NO+3H^2O

2NH^3+5/2 O^2------2NO+3H^2O

2NH^3+5/2 O^2------->2NO+3H^2O

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Answer:

mercury

Explanation:

mercury is a metal on the periodic table which is liquid at room temperature

A hiker climbs to the top of a mountain at rate of 0.5 m/hr. The speed of hiker is 1.3 x 10⁻⁴ m/s and the velocity of the hiker is 1.3 x 10⁻⁴ m/s west.

Speed is a scalar quantity. It is used to measure the distance traveled in a period of time. It is represented by -

s = d/Δt

where,

s = speed

d = distance

Δt = change in time

Velocity is a vector quantity. It is used to measure the change in position, that is, displacement over the change in time. It is represented by -

v = Δs / Δt

where,

v = velocity

Δs = change in position/displacement

Δt = change in time

The standard unit of velocity and speed both is m/s.

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19.2g/cm³

D = m / V

24.20g / 1.92ml = 19.2g/cm³

Answer:

what happened was when he dried off, there was still a little salt water on him. so, since the water has salt in it and the sun is very hot wich makes salty dried up as hard salt on him.

For producing 639L of [tex]SF_6[/tex], a volume of 1916.96L of [tex]F_2[/tex] gas is required for the reaction.

If the pressure and temperature at which the reaction occurs is known, we may use the ideal gas law to compute the stoichiometry of processes involving gases by using the connection between the volume (in liters) and quantity of gases (in moles). A chemical reaction's volume of gas can be evaluated by collecting it in an inverted vessel filled with water. The gas pushes water out of the vessel, and the amount of liquid displaced is proportional to the amount or volume of gas.

Given:

Volume of [tex]SF_6[/tex] = 639L

Pressure, P = 2atm

Temperature, T = 273.15K

To find:

Volume, V of [tex]F_2[/tex] gas = ?

Formula:

PV = nRT

Calculations:

No. of moles of [tex]SF_6[/tex] = 2 x 639 / 0.082 x 273.15

No. of moles of [tex]SF_6[/tex] = 57.057 moles

[tex]S (s) + 3F_2 (g) \rightarrow SF_6 (g)[/tex]

From the reaction,

1 mole of [tex]SF_6[/tex] is formed from 3 moles of [tex]F_2[/tex]

Therefore,

No. of moles of [tex]F_2[/tex] = 3 x 57.057 = 171.171 moles

Volume of [tex]F_2[/tex] = 171.171 x 0.082 x 273.15 / 2

Volume of [tex]F_2[/tex] = 1916.96L

Result:

1916.96L of [tex]F_2[/tex] gas is required to produce 639L of [tex]SF_6[/tex].

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