Part complete When a 235 92U nucleus is bombarded by neutrons (10n) it undergoes a fission reaction, resulting in the formation of two new nuclei and neutrons. The following equation is an example of one such fission process: 235 92U+10n→AZBa+9436Kr+310n
Enter the isotope symbol for the barium (Ba) nucleus in this reaction.In another process in which 235 92U undergoes neutron bombardment, the following reaction occurs:235 92U+10n --> AZSr+143 54Xe+310nEnter the isotope symbol for the strontium (Sr) nucleus in this reaction.

The enthalpy of neutralization of HCl and NaOH is 8.18 kJ/mol.

The enthalpy of neutralization is the heat released or absorbed when an acid and a base react to form one mole of water. In this case, the reaction is between hydrochloric acid (HCl) and sodium hydroxide (NaOH).

From the given information, 87 cm3 of 1.6 mol dm-3 HCl is neutralized by 87 cm3 of 1.6 mol dm-3 NaOH. The temperature rose from 298 K to 317.4 K.

To calculate the enthalpy change, we can use the formula:

Enthalpy change of neutralization = (mole of limiting reactant) x (heat evolved per mole of reaction)

From the balanced equation: HCl(aq) + NaOH(aq) -> NaCl(aq) + H2O(l)

This means that 1 mole of HCl reacts with 1 mole of NaOH to produce 1 mole of water. So, the heat evolved per mole of reaction is equal to the enthalpy change of neutralization.

Now, let's calculate the mole of the limiting reactant:

Given volume of HCl = 87 cm3 = 87 x 10-3 dm3

Given molarity of HCl = 1.6 mol dm-3

Mole of HCl = volume x molarity = (87 x 10-3) x 1.6 = 0.1392 mol

Since the mole of HCl and NaOH are equal, the mole of the limiting reactant is 0.1392 mol.

To determine the heat evolved per reaction, we need to divide the heat evolved by the mole of reaction:

Given temperature change = 317.4 K - 298 K = 19.4 K

Given the specific heat capacity of water = 4.18 J/K g

Assuming the density of the solutions is the same as water, we can use the mass of the solutions:

Mass of solution = volume x density = 87 x 10-3 dm3 x 1 g/cm3 = 87 g

Now, we can calculate the heat evolved:

Heat evolved = mass x specific heat capacity x temperature change = 87 g x 4.18 J/K g x 19.4 K = 8,177.56 J/mol

Convert the heat evolved from Joules to kilojoules:

The heat evolved = 8,177.56 J/mol = 8.18 kJ/mol (rounded to 2 decimal places)

Therefore, the enthalpy of neutralization of HCl and NaOH is 8.18 kJ/mol.

A main goal of most environmental scientists is to achieve biodiversity.

Answer : The pressure of the hydrogen gas exert before its volume was decreased will be, 2.28 atm

Explanation :

According to the Boyle's law, the pressure of the gas is inversely proportional to the volume of the gas at constant temperature of the gas and the number of moles of gas.

[tex]P\propto \frac{1}{V}[/tex]

or,

[tex]PV=k[/tex]

or,

[tex]P_1V_1=P_2V_2[/tex]

where,

[tex]P_1[/tex] = initial pressure of the gas = ?

[tex]P_2[/tex] = final pressure of the gas = 5.09 atm

[tex]V_1[/tex] = initial volume of the gas = 12.16 L

[tex]V_2[/tex] = final volume of the gas = 5.45 L

Now put all the given values in this formula, we get the initial pressure of the gas.

[tex]P_1\times 12.16L=5.09atm\times 5.45L[/tex]

[tex]P_1=2.28atm[/tex]

Therefore, the pressure of the hydrogen gas exert before its volume was decreased will be, 2.28 atm

Answer:

4.083 * 10^20 atoms.

Explanation:

One Mole of phosphorus  contains 6.022 * 10^23 atoms (Avogadros number)'

Since 1 mole of Phosphorus  has a mass of  30.974 grams, 21 milligrams has

6.022 * 10^23  * 0.021 / 30.974

= 0.004083 * 10^23

= 4.083 * 10^20

Acid rain is the process that involves  heavy chemicals falling to the Earth

as dry particles.

Acid rain is common in areas which have a lot of industries which release

chemicals into the atmosphere. With time, these chemicals accumulate and

falls to earth as dry particles through precipitation.

The acid rain normally contains water which pushes the chemicals down and the water is usually  acidic with a pH between 4.2 and 4.4 as a result of the chemicals.

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Answer:

B) Changing the enzyme concentration

The slowest way to regulate a reaction in a metabolic pathway is by changing the enzyme concentration.

It is series of chemical reactions that occurred in the cell. Metabolites referred to as species participating in an enzymatic reaction.

Role of Enzymes:

Enzymes act as catalysts – they allow a reaction to proceed more rapidly – and they also allow the regulation of the rate of a metabolic reaction

The binding of an enzyme to its substrate lowers the activation energy of the reaction. If an enzyme is present, the amount of energy needed to make a product is lowered.

In metabolic reactions there is transfer of electrons from one compound to another by processes catalyzed by enzymes.

Enzymes participates in increasing and decreasing the metabolism process inside our body. On increasing the substrate concentration, the rate of enzyme activity also increases.

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Answer:

177.8kJ/mol

Explanation:

In this reaction, the heat of decomposition is the same as the heat of formation. This is a decomposition reaction.

Given parameters:

ΔHf CaCO₃ = -1206.9kJ/mol

ΔHf CaO = −635.6 kJ/mol

ΔHf CO₂ = −393.5 kJ/mol

The heat of decomposition =

                     Sum of ΔHf of products - Sum of ΔHf of reactants

The equation of the reaction is shown below:

     CaCO₃ → CaO + CO₂

The heat of decomposition = [ -635.6 + (-393.5)] - [−1206.9 ]

                                             = -1029.1 + 1206.9

                                             = 177.8kJ/mol

The heat of decomposition given by the difference in the ΔH of product and reactant is 177.8 kj/mol

Given the equation for the decomposition process :

The heat for the decomposition process is the difference of the sum of heat of the product and the heat of the reactant :

Reactant :

Product :

Heat of decomposition :

Heat of decomposition = - 1029.1 - (- 1206.9)

Heat of decomposition = -1029.1 + 1206.9 = 177.8 kj/mol

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Answer:

Acetylcholine causes an end-plate potential by triggering the opening of sodium channels.

Acetylcholine (ACh), a neurotransmitter released by motor neurons, causes an end-plate potential by binding to receptors in the motor end plate and triggering a depolarization process that eventually leads to an action potential.

Acetylcholine (ACh) is a neurotransmitter that plays a pivotal role in triggering an end-plate potential within the neuromuscular system. The process starts when an action potential travels down the motor neuron's axon, triggering the release of these neurotransmitters. The ACh then binds to receptors in the motor end plate and initiates a series of events that lead to changes in ion permeability, the influx of sodium ions into the muscles cells, and ultimately a reduction in the voltage difference between the inside and outside of the cell - a process called depolarization. When ACh binds at the motor end plate, this depolarization is called an end-plate potential.

This depolarization then spreads along the muscle fiber membrane, the sarcolemma, creating an action potential, which moves across the entire cell, creating a wave of depolarization. Therefore, the acetylcholine indeed causes the end-plate potential by triggering the release of these neurotransmitters and the subsequent sequence of events.

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Answer:

lowers activation energy

Answer:

Explanation:

An enzyme reduces the free energy of activation (EA) of the reaction it catalyzes.

Answer:

a. have an excess number of neutrons.

Explanation:

Every atomic nucleus  have a specific neutron/proton ratio that makes them stable. Any nucleus with a neutron/proton ratio that differs from the stability ration will become unstable. An unstable nucleus will split up and emit small particles of matter and/electromagnetic ionizing radiation. This makes an atom radioactive.

Therefore, an atom with excess number of neutrons is a radioactive isotope.

Answer:

b. 9.29 L is the new volume of the gas if the pressure is constant.

Explanation:

As per Charles’s law  

At constant pressure for a given amount of a gas,

Volume is directly proportional to its temperature.

Thus the expression is [tex]V \propto T[/tex]

[tex]\frac {V}{T} = k[/tex] where k is a constant  

When there is a change in the volume and temperature the expression will be

[tex]\frac {V_1}{T_1} = \frac {V_2}{T_2}[/tex]

where [tex]V_1[/tex] and [tex]T_1[/tex] are the initial volume and initial temperature and [tex]V_2[/tex] and [tex]T_2[/tex] are the final volume and temperature.

Plugging in the values given

[tex]\frac {(9.3L)}{(279.5K)}=\frac {V_2}{(279.1K)}[/tex]

[tex]V_2=\frac {(9.3L\times279.1K)}{279.5K} \\\\=9.29L[/tex]

(Answer)

Answer:

This ion is in an octahedral geometry.

See the diagram attached for the Lewis Dot Structure of the iodide hexafluoride cation [tex]\rm {IF_6}^{+}[/tex]. (Created with Google Drawings.)

Note that in this diagram,

Explanation:

The iodine in [tex]\rm {IF_6}^{+}[/tex] forms an expanded octet. There are twelve valence electrons in total around this atom.

Overall, there needs to be [tex]6 \times 1 + 5 + 1= 12[/tex] more electrons for seven atoms to achieve an octet. They will form half that number of chemical bonds. That's [tex]12 / 2 = 6[/tex] bonds.

Now consider: what will be the geometry of this ion? There are six chemical bonds but no lone pair around the central iodine atom. The six [tex]\mathrm{I-F}[/tex] bonds repel each other equally. They will stay as far apart from each other as possible. As a result, the shape of the ion will be octahedral. Each of the fluorine atoms occupies a vertex.

Answer:

Exothermic

Explanation:

An exothermic reaction results when the energy released by the formation of products is greater than the energy required to break the bonds in the reactants.

Answer:

Explanation:

1) Data:

2) Formula:

Combined law of gases:

3) Solution:

T₂ = P₂ V₂ T₁ / (P₁ V₁)

T₂ = 872.15 mmHg × 7.63 liter × 261.2 K / ( 424.9 mmHg × 0.66 liter)

T₂ = 6198 K

Answer: pH = 4.11

Explanation: pH of the buffer solution is calculated using Handerson equation:

[tex]pH=pKa+log(\frac{base}{acid})[/tex]

pKa is calculated from the given Ka value as:

pKa = - log Ka

[tex]pKa=-log1.34*10^-^5[/tex]

pKa = 4.87

pH of the solution before adding HCl to it:

[tex]pH=4.87+log(\frac{0.112}{0.322})[/tex]

pH = 4.87 - 0.46

pH = 4.41

Now, 0.069 moles of HCl are added to the buffer solution. This added HCl react with base(sodium propanoate) to produce acid(propanoic acid).

Initial moles of acid = 0.322*1.44 = 0.464

initial moles of base = 0.112*1.44 = 0.161

moles of base after reacting with HCl = 0.161 - 0.069 = 0.092

moles of acid after addition of HCl = 0.464 + 0.069 = 0.533

Let's plug in the values in Handerson equation to calculate the pH:

[tex]pH=4.87+log(\frac{0.092}{0.533})[/tex]

pH = 4.87 - 0.76

pH = 4.11

So, the original pH of the buffer solution is 4.41 and after addition of HCl the pH is 4.11 .

The pH of solution following the addition of 0.069 moles of HCl is 4.11.

The pH of a buffer solution can be calculated using Handerson equation as follows:

pH = pka + log (base/acid)

pKa of the acid is calculated from the given Ka value as follows:

pKa = - log Ka

pKa = - log 1.34 × 10-⁵

pKa = 4.87

The pH of the solution before adding HCl to it is as follows:

pH = 4.87 + log(0.112/0.322)

pH = 4.87 - 0.46 = 4.41

According to this question, 0.069 moles of HCl are added to the buffer solution.

Therefore, the pH of the buffer after adding HCl is:

pH = 4.87 + log(0.092/0.533)

pH = 4.87 - 0.76 = 4.11

Therefore, the pH of solution following the addition of 0.069 moles of HCl is 4.11.

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Answer:

Hygroscopic

Explanation:

An hygroscopic substance is one that absorbs moisture from the atmosphere and becomes wet. Their ability to remove water from air is less than that of deliquescent substances. Most of the solid hygroscopic substances forms pasty substances and not solutions like the deliquescent compounds.

Examples are sodium trioxonitrate(v), copper(ii) oxide e.t.c

Efflorescence compounds gives off their water of crystallization to the atmosphere.

Hydrates capable of removing moisture from the air due to their low vapor pressure are known as hygroscopic.

Hydrates that have a low vapor pressure and can remove moisture from air are hygroscopic. Substances such as anhydrous calcium chloride and magnesium chloride exhibit hygroscopic properties due to their ability to absorb moisture, ultimately becoming hydrates in the process.

For example, anhydrous calcium chloride mixed with cobalt chloride serves as both a drying agent and an indicator; cobalt chloride is blue when anhydrous and pink when hydrated, thus revealing the condition of the desiccant.

Furthermore, the presence of nonvolatile solutes, such as these hydrates, can lower the vapor pressure of a solution by preventing the evaporation of solvent molecules. The waters of hydration in compounds are loosely bound water molecules that can often be removed through heating, turning hydrates back into their anhydrous form.

Answer : The percent composition by volume of mixture of [tex]CO[/tex] and [tex]CO_2[/tex] are, 18.94 % and 81.06 % respectively.

Solution :

According to the Graham's law, the rate of effusion of gas is inversely proportional to the square root of the molar mass of gas.

[tex]R\propto \sqrt{\frac{1}{M}}[/tex]

And the relation between the rate of effusion and volume is :

[tex]R=\frac{V}{t}[/tex]

or, from the above we conclude that,

[tex](\frac{V_1}{V_2})^2=\frac{M_2}{M_1}[/tex]            ..........(1)

where,

[tex]V_1[/tex] = volume of helium gas = 29.7 ml

[tex]V_2[/tex] = volume of mixture = 9.28 ml

[tex]M_1[/tex] = molar mass of helium gas  = 4 g/mole

[tex]M_2[/tex] = molar mass of mixture = ?

Now put all the given values in the above formula 1, we get the molar mass of mixture.

[tex](\frac{29.8ml}{9.28ml})^2=\frac{M_2}{4g/mole}[/tex]

[tex]M_2=40.97g/mole[/tex]

The average molar mass of mixture = 40.97 g/mole

Now we have to calculate the percent composition by volume of the mixture.

Let the mole fraction of [tex]CO[/tex] be, 'x' and the mole fraction of [tex]CO_2[/tex] will be, (1 - x).

As we know that,

[tex]\text{Average molar mass of mixture}=\text{Mole fraction of }CO[/tex]

[tex]\text{Average molar mass of mixture}=(\text{Mole fraction of }CO\times \text{Molar mass of } CO)+(\text{Mole fraction of }CO_2\times \text{Molar mass of } CO_2)[/tex]

Now put all the given values in this expression, we get:

[tex]40.94g/mole=((x)\times 28g/mole)+((1-x)\times 44g/mole)[/tex]

[tex]x=0.1894[/tex]

The mole fraction of [tex]CO[/tex] = x = 0.1894

The mole fraction of [tex]CO_2[/tex] = 1 - x = 1 - 0.1894 = 0.8106

The percent composition by volume of mixture of [tex]CO[/tex] = [tex]0.1894\times 100=18.94\%[/tex]

The percent composition by volume of mixture of [tex]CO_2[/tex] = [tex]0.8106\times 100=81.06\%[/tex]

Therefore, the percent composition by volume of mixture of [tex]CO[/tex] and [tex]CO_2[/tex] are, 18.94 % and 81.06 % respectively.

Answer:

C. If it is tested and the evidence does not support it.

Explanation:

A hypothesis is more less a scientific guess. Before such a guess or prediction is made, empirical observations and deductions are first made. It is from the result of the observations that a hypothesis statement is made.

For a hypothesis to become widely adopted and accepted, it must be testable within the limits of the experiment as described by the proposer. When subjected to test and it agrees, the status of a hypothesis can be upgraded.

If the hypothesis is tested and evidence contrasts the result being sort for, a hypothesis will be discarded.

Answer : The number of moles of gas added to the container will be, 20.89 mole

Explanation :

According to the Avogadro's law, the volume of gas is directly proportional to the number of moles of gas at same pressure and temperature. That means,

[tex]V\propto n[/tex]

or,

[tex]\frac{V_1}{V_2}=\frac{n_1}{n_2}[/tex]

where,

[tex]V_1[/tex] = initial volume of gas  = 8.15 L

[tex]V_2[/tex] = final volume of gas  = 17.9 L

[tex]n_1[/tex] = initial number of moles of gas  = 9.51 mole

[tex]n_2[/tex] = final number of moles of gas  = ?

Now we put all the given values in this formula, we get  the final moles of gas.

[tex]\frac{8.15L}{17.9L}=\frac{9.51mole}{n_2}[/tex]

[tex]n_2=20.89mole[/tex]

Therefore, the number of moles of gas added to the container will be, 20.89 mole

Answer:

propanoic acid forms hydrogen bonded dimers and 1-butanol does not.

Explanation:

Propanoic acids will have a higher boiling point because it forms dimers.

The two compounds have hydrogen bonds as their predominant intermolecular bonds. The intermolecular determines a lot about the physical properties of a substance such as it's viscosity, boiling point, melting point etc.

The two compounds have hydrogen bonds which are bonds that occur between between hydrogen and a more electronegative atom. The electronegative atoms are usually oxygen,nitrogen and fluorine.

In a compound of 1-butanol, we have just a single hydrogen bond between the hydrogen on one compound and the oxygen on the hydroxyl group of another one.

For, propanoic acids, dimerization occurs. Here, we have two hydrogen bonds. The alkanoic acid functional group furnishes the bond. This bond forms between the carbonyl group and hydrogen on a compound and the hydroxyl group and another hydrogen on the same compound.

Answer:

B. Peer review

Explanation:

Peer review ensures that the results of an experimental procedures are consistent are reliable and they meet their objective statement.

When peers which are professionals in a field of study subjects the results from an experiment into a test, they can give their own verdict as to wether such findings are consistent and reliable with the problem in view.

Answer:

the answer would be peer review

Explanation:

founders education chemistry

Answer:

because energy is released

Explanation:

freesing is an exothermic process

C. Because energy is released, freezing is an endothermic process.

In thermochemistry, an endothermic system is any process with an increase in the enthalpy H of the system. In such a process, a closed system usually absorbs thermal energy from its surroundings, which is heat transferred into the system.

Endothermic reactions are chemical reactions wherein the reactants absorb heat energy from the surroundings to form products. these reactions lower the temperature in their surrounding region, thereby creating a cooling effect.

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Answer:

=0.5 moles

Explanation:

Let us assume that the sodium chloride solution has a density of 1g/cm³.

Therefore the volume of the 0.5 kg of solution will be calculated as follows.

0.5kg into grams=0.5 kg×1000g/kg

=500g

volume= mass/density

=500g/1g/cm³

=500cm³

The solution is 1.0 M which means that 1.0 moles are in 1000 cm³

500cm³ will have:

(500 cm³×1.0 moles)/1000 cm³

=0.5 moles

Answer:  Hypothesis

Explanation:  Hypothesis is a kind of idea that has been put forward prior to experimentation and whose results are not out yet.

The laws makes the theory then there are some rules which are needed to be followed in order to make the most out of the experiments. Then prior to the experiments , there comes the hypothesis whis the explanation of the work and which would be tested through the experiments.

Answer:

option B

Explanation:

A spontaneous reaction drive favorable when enthalpy is decreasing and the entropy is increasing on the system. If that happens the reaction occurs spontaneously

Answer:

b. decreasing enthalpy and increasing entropy

Explanation:

∆H stands for enthalpy change and ∆S stands for entropy change

Spontaneity depends on the enthalpy and entropy changes of the reaction

∆G = ∆H - T∆S

When ∆H is negative and ∆S is positive  

∆G will be negative

For a spontaneous reaction ∆G is negative

If ∆G = 0 then the reaction will be at equilibrium  

If ∆G is positive the reaction is non spontaneous.

Decreasing enthalpy (negative) and increasing entropy (positive) will give a negative number for [tex]\Delta G[/tex]

Answer:

The order of increasing entropy will be:

1 mol of NaCl (s) at 25 ° C < 1 mol of HCl (g) at 25 ° C<  1 mol of HCl (g) at 50 ° C < 2 mol of HCl (g) at 50 ° C

Explanation:

The entropy increases with

a) increase in temperature

b) state of matter (the entropy order of matter is gas > liquid > solid)

So here

i) 1 mol of HCl (g) at 50 ° C : it is gas at high temperature as compared to HCl gas at lower temperature.

ii. 1 mol of NaCl (s) at 25 ° C : this is solid so will have lower entropy than gas.

iii. 2 mol of HCl (g) at 50 ° C: the moles are more so will have more entropy than 1 mol of HCl (g) at 50 ° C

iv. 1 mol of HCl (g) at 25 ° C : will have lower entropy than HCl gas at higher temperature but will have higher entropy than solid NaCl.

The correct order of increasing entropy is given as:

1 mol of NaCl (s) at 25 ° C < mol of HCl (g) at 50 ° C < 1 mol of HCl (g) at 25 ° C < 2 mol of HCl (g) at 50 ° C

Entropy can be defined as that measure of thermal energy of a system per unit temperature that is unavailable for doing work.

Mathematically, the entropy change in a chemical reaction is given by:

The sum of the entropies of the products - the sum of the entropies of the reactants.

In conclusion, the correct order of increasing entropy is given as

1 mol of NaCl (s) at 25 ° C < mol of HCl (g) at 50 ° C < 1 mol of HCl (g) at 25 ° C < 2 mol of HCl (g) at 50 ° C

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Answer:

The ones with 8 protons

Explanation:

Since there are two of them with 8 protons, we can assume they are the same element. The first 8 proton element has 10 neutrons while the second has 11. This makes them isotopes of one another

Answer:

77.6%

Explanation:

Parameters given:

Number of moles of H₂ = 1 mole

Actual yield = 14g

Equation of the reaction:

                 2H₂ + O₂ → 2H₂O

Solution

From the statement of the problem, we have been given the actual yield that was obtained during the laboratory procedure. Now, we find the theoretical yield and this would lead us to the percentage yield.

 Percentage yield = [tex]\frac{actual yield}{Theoretical yield}[/tex] x 100

Theoretical yield:

  From the stoichiometeric equation:

            2moles of H₂ produced 2 moles of water

      Hydrogen gas the limiting reactant and it is in short supply,

   Therefore, 1 mole of water would be produced by 1 mole of hydrogen gas.

We use this to estimate the mass of the water that would be produced:

         mass of water = number of moles of water x molar mass of water

Molar mass of H₂O = (2x1) + 16 = 18gmol⁻¹

          mass of water = 1 mol x 18gmol⁻¹ = 18g

This is the theoretical yield

Percentage yield = [tex]\frac{actual yield}{Theoretical yield}[/tex] x 100

Percentage yield = [tex]\frac{14}{18}[/tex] x 100 = 77.6%