is the second one or the fourth one?

Answer:

am going to work it out

Explanation:

i am going to work it out and then tell you the answer ok

Answer:

no I am in 8 standard

I am already preparing for a doctor for my future

Answer:

23.55°C

Explanation:

Based on the equation:

Ca²⁺(aq) + 2F⁻(aq) → CaF₂(s) ∆H°=-11.5 kJ

When 1 mole of Ca²⁺ and 2 of F⁻ reacts, 11.5kJ are released.

Thus, we need to find moles of reaction to find the heat released and using:

C = SₓmₓΔT

We can find the final temperature as follows:

Moles of reaction:

0.0500L * (0.400mol / L) = 0.0200moles Ca²⁺ = Moles of reaction

Heat produced is:

0.0200 moles * (11.5kJ / mol) = 0.23kJ

Using:

C = SₓmₓΔT

Where C is heat = 230J

S is specific heat = 4.18J/g

m is mass of solution = 100.00g

And ΔT is change in temperature

230J = 4.18J/gₓ100.00gₓΔT

ΔT = 0.55°C

As initial temperature is 23.0°C

Final temperature = 23.0°C + 0.55°C =

The final temperature of the solution is 23.55°C.

We were given the equation

Ca²⁺(aq) + 2F⁻(aq) → CaF₂(s) ∆H°=-11.5 kJ

This means that 1 mole of Ca²⁺ and 2 of F⁻ reacts to form CaF₂ and  1.5kJ is released.

The formula we need to use is C = SₓmₓΔT

where c is heat, s is specific heat, m is number of mole and ΔT is temperature change.

We need to find the moles of reaction first

Moles of reaction = 0.0500L × (0.400mol / L) = 0.0200moles Ca²⁺

Heat produced = 0.0200 moles ×11.5kJ / mol = 0.23kJ

We can then substitute into the formula

C = SₓmₓΔT

C = 230J

S = 4.18J/g

m = 100.00g

ΔT= ?

230J = 4.18J/gₓ100.00gₓΔT

         = 0.55°C

Since the  initial temperature is 23.0°C

The Final temperature will be 23.0°C + 0.55°C

                                               =23.55°C

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Answer:

135 moles

Explanation:

300*0.45

= 135

PLS GIVE BRAINLIEST

3/2 moles

We are given:

Molarity of the solution = 0.450 M

Volume of the Solution = 300 mL OR 0.3 L

Solving for the number of moles:

We know that the formula for molarity:

M = nV          (where n is the number of moles and V is the volume in Liters)

replacing the variables

0.450 = n * (0.3)

n = 0.450 / 0.3

n = 3/2 moles

Therefore, we have 3/2 moles of Na(OH) in the give solution

Answer:

Melting = endothermic, solid = exothermic

Explanation:

Ok so when ice cream melts, that requires heat, so it’s Endothermic. In order to melt it, it requires heat, heat is entering. When it becomes solid again, that is exothermic because it is losing heat in order to become cool again.

Answer:

ΔU° = 56.0 J

Explanation:

Step 1: Given data

Step 2: Calculate the change in the internal energy of the gas (ΔU°)

The internal energy of a gas is the energy contained within it. We can calculate it using the following expression.

ΔU° = q + w

ΔU° = -27.0 J + 83.0 J

ΔU° = 56.0 J

Answer:

no

Explanation:

Answer:

[tex]C_{metal}=126.6\frac{J}{g\°C}[/tex]

Explanation:

Hello!

In this case, when two substances at different temperature are put in contact and an equilibrium temperature is attained, we can evidence that the heat lost by the hot substance (metal) is gained by the cold substance (water) and we can write:

[tex]Q_{metal}=-Q_{water}[/tex]

Which can be also written as:

[tex]m_{metal}C_{metal}(T_{EQ}-T_{metal})=-m_{water}C_{water}(T_{EQ}-T_{water})[/tex]

Thus, since we need the specific heat of the metal, we solve for it as shown below:

[tex]C_{metal}=\frac{m_{water}C_{water}(T_{EQ}-T_{water})}{-m_{metal}(T_{EQ}-T_{metal})} \\\\C_{metal}=\frac{250.0g*4.184\frac{J}{g\°C}(29.0\°C-98.0\°C)}{95.0g(29.0\°C-23.0\°C)} \\\\C_{metal}=126.6\frac{J}{g\°C}[/tex]

Best regards.

The molarity of calcium bicarbonate if 9.52 mL of 1.20 M HNO3 is required in a titration to neutralize 50.0 mL of a solution of Ca(HCO3)2 is 0.228M.

HOW TO CALCULATE MOLARITY:

C1V1 = C2V2

Where;

According to this question;

1.20 × 9.52 = C2 × 50

11.424 = 50C2

C2 = 11.424 ÷ 50

C2 = 0.228M

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Answer:

The elements that have the same number of energy levels or the orbitals.

Explanation:

They have he same number -- energy levels

Answer:

3.34x10²⁴ molecules of oxygen

Explanation:

1 Mole of particles of any kind of gases or particles are always 6.022x10²³.

1 mole of electrons are 6.022x10²³ electrons

1 mole of any gas are 6.022x10²³ molecules

1 mole of oxygen are 6.022x10²³ molecules. Thus, 5.55 moles are:

Answer:

pH = 9.11

Explanation:

First, using gas law, we will determine the moles of NH3 bubbled. Then, with moles of HCl we can determine how many NH4⁺ are produced. As last, using H-H equation for bases we can find pOH and pH of the solution:

Moles NH3:

PV = nRT

P = pressure: 743 torr * (1atm / 760torr) = 0.9776atm

V = volume: 7.4L

n = Moles. Our incognite

R = Gas constant: 0.082atmL/molK

T is absolute temperature: 273.15K + 22°C = 295.15K

PV / RT = n

0.9776atm*7.4L / 0.082atmL*295.15K = 0.30 moles of NH3

Moles HCl:

0.50L * (0.35mol / L) = 0.175 moles of HCl

Based on the reaction:

NH3 + HCl → NH4⁺ + Cl⁻

All HCl added is producing NH₄⁺ = 0.175 moles NH₄⁺

Moles NH₃: 0.30moles NH3 - 0.175 moles = 0.125 moles NH₃

H-H equation for bases is:

pOH = pKb + log [BH+] / [B]

Where pKb = -log Kb = 4.74

[BH+] could be taken as moles of NH4+ = 0.175 mol

[B] are moles of NH3 = 0.125 mol

pOH = pKb + log [BH+] / [B]

pOH = 4.74 + log [0.175mol] / [0.125mol]

pOH = 4.89

pH = 14-pOH

Answer:

The amount of heat required to raise the temperature of a 32g sample of water from 8°C to 22°C is 1,874.432 J

Explanation:

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

Between heat and temperature there is a direct proportional relationship. The constant of proportionality depends on the substance that constitutes the body and its mass, and is the product of the specific heat and the mass of the body. So, the equation that allows to calculate heat exchanges is:

Q = c * m * ΔT

where Q is the heat exchanged by a body of mass m, constituted by a substance of specific heat c and where ΔT is the variation in temperature.

In this case:

Replacing:

Q= 32 g* 4.184 [tex]\frac{J}{g*C}[/tex] *14 °C

Solving:

Q= 1,874.432 J

The amount of heat required to raise the temperature of a 32g sample of water from 8°C to 22°C is 1,874.432 J

Answer: E

Explanation:hope this helps you out

Answer:

The different ways to represent compounds are chemical formulas and molecular models. There are so many ways to represent compounds so that a particular formula can be used depending upon how much information is provided and how much is needed to be share.

Explanation:

The representation of molecules depends on what property of the molecule we want to explore.

A molecule is composed of atoms of molecules. The representation of molecules depends on what property of the molecule we want to explore.

A molecule can be represented using;

In each case, a particlar feature of the molecule is more vividly expressed.

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we are given the molarity and the volume of solution. The only issue is that the volume is given in mL instead of L. This issue can be fixed by using the following conversion factor:

a

a

a

a

a

a

a

a

a

a

a

a

a

a

a

a

a

a

a

a

a

1000

m

L

=

1

L

Therefore, if we divide 50mL by 1000mL we will obtain a value of 0.05L.

Next, the equation has to be rearranged to solve for the moles of solute:

Moles of solute = Molarity

×

Liters of solution

Now, multiply 0.360 M by 0.05:

0.360 mol

1 L

×

0.05 L

=

0.018 mol

To obtain the mass of solute, we will need to the molar mass of NaCl, which is 58.44 g/mol:

Finally, multiply the number of moles by 58.44 g/mol

0.018

mol

×

58.44

g

1

mol

Boom, here it is:

1.05

g

Answer: 0.923 L

Explanation: The reaction between naoh and h3po4 is:

3naoh + h3po4 —> na3po4 + 3h20

this means it requires 3 mols of naoh to make na3po4

given the concentration, 3.25 M, the equation looks like this:

3.0 mol x (1.0L/ 3.25mol) = 0.923 L

To prepare 250 ml 0.25 M hydrogen peroxide, 10.63 ml of 20g/100 ml hydrogen peroxide has been taken and made up the volume to 250 ml.

The dilution of the sample can be prepared with the help of expression:

M1V1 = M2V2

M1 = molarity of the concentrated solution

V1 = volume of concentrated solution

M2 =  molarity of diluted solution

V2 = volume of diluted solution.

The molarity of concentrated solution has been:

Molarity = [tex]\rm \dfrac{weight}{molecular\;weight}\;\times\;\dfrac{1000}{Volume\;(ml)}[/tex]

The 20g/100 ml Hydrogen peroxide has molarity:

Molarity = [tex]\rm \dfrac{20}{34.0147}\;\times\;\dfrac{1000}{100}[/tex]

Molarity of Hydrogen peroxide = 5.879 M

The volume of 5.879 M hydrogen peroxide is required to prepare 0.25 M hydrogen peroxide has been:

Volume of Hydrogen peroxide (20g/100 ml) [tex]\times[/tex] 5.879 = 250 ml [tex]\times[/tex] 0.25 M

Volume of Hydrogen peroxide (20g/100 ml) = 10.63 ml.

To prepare 250 ml 0.25 M hydrogen peroxide, 10.63 ml of 20g/100 ml hydrogen peroxide has been taken and made up the volume to 250 ml.

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Answer:

12 π electrons.

Explanation:

The structure of adenine can be seen below.

From the diagram, the total number of electrons in adenine is 70 electrons where 20 of them are core electrons.

Also from this same structure, we will notice that we have a total number of  12 π electrons.

i.e.

Each one of these five atoms described takes part in the π electron. These are N-1, N-3, N-7 which comprise of 2σ bonds, and also each of three N contributes one π electron.

Similarly, N-9 and N-10 contain 3σ bonds; Hence, each of them donates two electrons.

Thus;

5C = 5π electrons

3N = 3π electrons

2N = 4π electrons

     = 12π electrons

Answer:

What’s the answer

Explanation:

I neeeddsdd

The statements correctly describes the function of cell parts is the mitochondria are the power plants of the cell. Therefore, option C is correct.

The cytoplasm of a cell contains tiny structures (fluid that surrounds the cell nucleus). The majority of a cell's energy is produced by mitochondria, which also have unique genetic material distinct from that present in the nucleus.

Oxidative phosphorylation, which produces ATP using the energy generated during the oxidation of the food we ingest, is the traditional function of mitochondria.

For the majority of biochemical and physiological activities, including growth, mobility, and equilibrium, ATP is used as the main energy source in turn.

Thus, option C is correct.

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Answer:

Water is heated as it travels through flat, glazed panels known as solar collectors, which are normally situated on the roof of the building. The heated water is then stored in an insulated storage tank.

The number of mole of NaCl needed to react with excess Pb²⁺ to produce 45.5 g of PbCl₂ is 0.328 mole

We'll begin by calculating the number of mole in 45.5 g of PbCl₂. This can be obtained as follow:

Mass of PbCl₂ = 45.5 g

Molar mass of PbCl₂ = 207 + (35.5×2) = 278 g/mol

Mole = mass / molar mass

Mole of PbCl₂ = 45.5 / 278

2NaCl + Pb²⁺ —> PbCl₂ + 2Na⁺

From the balanced equation above,

2 moles of NaCl reacted to produce 1 mole of PbCl₂

Therefore,

Xmol of NaCl will react to produce 0.164 mole of PbCl₂ i.e

Xmol of NaCl = 2 × 0.164

Xmol of NaCl = 0.328 mole

Thus, the number of mole of NaCl needed for the reaction is 0.328 mole

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Answer:The properties of magnets are used to make electricity.

Explanation: Moving a magnet around a coil of wire, or moving a coil of wire around a magnet, pushes the electrons in the wire and creates an electrical current. Electricity generators essentially convert kinetic energy (the energy of motion) into electrical energy.

Answer: When the metamorphic rock continues to heat up it will eventually melt creating molten rock. When it cools it will become igneous rock

Explanation:

:D

Answer:

As metamorphic rock continues to heat up, it can eventually melt and become molten/magma. When the molten rock cools it forms an igneous rock.

Explanation:

basically it need heat as hot as lava.

Answer:

The quantity of heat required to melt all the ice at 0°C is 2.21 * 10⁶ J

Explanation:

Latent heat of fusion  is the heat absorbed by a unit mass of a given solid at its melting point that completely converts the solid to a liquid at the same temperature. Its unit is Joules/kg or Joules/g.

1 calorie = 4.184 Joules

Therefore , 80.0 cal/g = 80.0 cal/g * 4.184 J/cal = 334.72 J/g

1 g = 0.001 kg; Heat of fusion in J/kg = 334.72 J/g * 1g /0.001 kg = 3.35 * 10⁵ J/kg

Quantity of heat, Q = mass * latent heat of fusion of ice

quantity of heat required = 6.60 kg * 3.35 * 10⁵ J/kg

Quantity of heat required = 2.21 * 10⁶ J

Therefore, the quantity of heat required to melt all the ice at 0°C is 2.21 * 10⁶ J

Answer: 5 months

Explanation: Rate Law for a reaction is an equation relating the reaction rate of reactants. It is expressed as:

aA + bB → cC + dD

[tex]r=k[A]^{a}[B]^{b}[/tex]

in which k is the rate constant of the reaction

Zero-order Kinetics is a chemical reaction in which the rate doesn't change with the variations in concentration of the reactants. At this state, it is possible to determine the final concentration by using:

[tex][A]=-kt+[A_{0}][/tex]

Shelf-Life is the time required for 10% of a drug or material to desintegrate: it is the time necessary for A to desintegrate 90% of its original concentration.

Then, the shelf-life for the drug is

[tex][A]=-kt+[A_{0}][/tex]

[tex]90=-2t+100[/tex]

2t = 10

t = 5

Shelf-life for a drug which decomposes by zero-order kinetics with rate constant of 3mgmL^{-1}month^{-1} is 5 months

The shelf life for a drug suspension decomposes by zero-order kinetics with a rate constant of 2 mg mL-1month-1 is 5 months.

Shelf life for the zero order reaction will be calculated by using the below equation as:

[A] = -kt + [A₀], where

[A₀] = initial concentration of drug suspension = 100 mg/mL

[A] = Final concentration of drug suspension after 10% decomposition = 100-10 = 90mg/mol

k = rate constant = 2 mg/mL.month

t = shelf lime = to find?

On putting all these values on the above equation we get

90 = -2×t + 100

t = 10/2 = 5 months

Hence, 5 months is the shelf life.

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