ACTIVITY: SOLUTION CONCENTRATION VS. CONDUCTIVITY
Here is your goal for this lesson:
Graph experimental data and interpret results for peer review
A chemistry student carried out an experiment with a conducting apparatus (ammeter) similar to the one below. This ammeter measures in milliamperes (mA). The following data was taken.
Solution Reading
0.1 M H2SO4 150 mA
0.1 M Ba(OH)2 150 mA
To 30 mL of the Ba(OH)2 solution, 10 mL portions of H2SO4 were added until a total of
50 mL of H2SO4 were used. The following results were recorded.
DATA TABLE
Total H2SO4 Added Meter Reading Observations
0 mL 150 mA Ba(OH)2 and H2SO4 clear, colorless
10 mL 65 mA milky white precipitate forms
20 mL 31 mA more precipitate forms
30 mL 0 mA precipitate heavy and settles
40 mL 29 mA no added precipitate seen to form
50 mL 62 mA no change seen
Questions
1. Did you plot the data? yes or no
2. Did you label your graph axes? no or yes
3. Did you give your graph a title? no or yes
4. Does the Ba(OH)2 solution contain ions? yes or no
5. Does the H2SO4 solution contain ions? yes or no
6. Explain the data.
Is there any evidence that a reaction has occurred?
7. Does the conductivity increase or decrease?
8. Does the number of ions in solution increase, decrease, or remain constant?
9. What is the indicator of the number of ions in solution?
10. How does this evidence indicate that the reaction has occurred between ions?
11. The Ba(OH)2 dissociates as Ba+2 + 2 OH-. H2SO4 dissociates as 2 H+ + SO4-2.Write a balanced equation for this reaction.
12. When the conductivity is at a minimum, what must be true about the amount of Ba(OH)2?
13. Why does it not conduct at this low point?
14. Why does it conduct more before and after this minimum point?

Answer:

The change in cell potential under non-standard conditions can be predicted using the Nernst equation. The Nernst equation relates the measured cell potential to the reaction quotient and allows the accurate determination of equilibrium constants (including solubility constants).

In this case, the concentrations of Al³+ and Ni²+ are not standard. According to the Nernst equation, an increase in the concentration of the oxidizing agent ion in the cathodic side of the system (reduction reaction) should result in an increase in cell potential. Conversely, an increase in the concentration of the reducing agent in the anodic side of the system (oxidation reaction) should result in a decrease in cell potential.

Explanation:

The Nernst equation enables the determination of cell potential under non-standard conditions. It relates the measured cell potential to the reaction quotient and allows the accurate determination of equilibrium constants (including solubility constants).

The Nernst equation is given by:

Ecell = E°cell - (RT/nF)lnQ

where Ecell is the cell potential under non-standard conditions, E°cell is the standard cell potential, R is the universal gas constant, T is the temperature in kelvins, n is the number of moles of electrons transferred in the balanced equation for the cell reaction, F is Faraday’s constant, and Q is the reaction quotient.

At room temperature (25°C or 298K), this equation can be simplified to:

Ecell = E°cell - (0.0592/n)logQ

where logQ is the base-10 logarithm of the reaction quotient.

To calculate the change in cell potential using this equation, you need to know the standard cell potential (E°cell), the number of moles of electrons transferred in the balanced equation for the cell reaction (n), and the reaction quotient (Q) under non-standard conditions.

The reaction is endothermic since the energy level of the products have are higher than that of the reactants.

The activation energy (AE) is the energy difference between the reactants and the transition state.

The change in energy E and the energy difference between the reactants and the products

The data given is as follows:

Reactants: 0 kJ/mol

AE forward 125 kJ/mol

AE reverse: 86 kJ/mol

Products: 39 kJ/mol

The values of ΔE forward and ΔE reverse are as follows:

ΔE forward = (39 - 0) kJ/mol

ΔE forward = +39 kJ/mol

ΔE reverse = (0 - 39) kJ/mol

ΔE reverse =  -39 kJ/mol

3. Given that Ea = 154 kJ/mol and ΔE = 136 kJ/mol

AE reverse = ΔE - AE forward

E = 136 kJ/mol - 154 kJ/mol

E = -18 kJ/mol

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The specific heat capacity of the metal can be calculated to be 2.03 J/g･ °C. This result can be explained by the fact that the heat lost by the metal is equal to the heat gained by the ethylene glycol, since no other source of heat is present.

Specific heat capacity is the amount of heat energy needed to raise the temperature of a unit mass of a substance by 1 degree Celsius. It is measured in joules per kilogram Kelvin (J/kg K).

The specific heat capacity (c) of the metal can be calculated using the following equation:

Q = mc∆T

Where Q is the heat lost by the metal, m is the mass of the metal, and ∆T is the change in temperature of the metal.

Q = (115.0 g)(c)(165.0 °C - 25.8 °C)

On the other hand, the heat gained by the ethylene glycol can be calculated using the following equation:

Q = (265.0 g)(2.43 J/g･ °C)(41.5 °C - 25.8 °C)

By equating the two equations, we can solve for the specific heat capacity of the metal:

(115.0 g)(c)(165.0 °C - 25.8 °C) = (265.0 g)(2.43 J/g･ °C)(41.5 °C - 25.8 °C)

c = 2.03 J/g･ °C

Therefore, the specific heat capacity of the metal can be calculated to be 2.03 J/g･ °C.

This result can be explained by the fact that the heat lost by the metal is equal to the heat gained by the ethylene glycol, since no other source of heat is present.

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1) The molar mass of the acid of the titration curve is 166 g/mol

2) The pKa of the acid of the titration curve is 4.97.

1) The molar mass of the acid can be determined from the equivalence point of the titration curve

Mass of acid sample = 0.431 g

Volume of KOH solution at equivalence point = 24.0 mL = 0.0240 L

Molarity of KOH solution = 0.108 M

Number of moles of KOH added at equivalence point = Molarity x Volume

= 0.108 M x 0.0240 L

= 0.00259 moles

Number of moles of acid = Number of moles of KOH added

= 0.00259 moles

Molar mass of acid = Mass of acid sample ÷ Number of moles of acid

= 0.431 g ÷ 0.00259 moles

= 166 g/mol

2) The pKa of the acid can be determined from the half-equivalence point of the titration curve.

Volume of KOH solution at half-equivalence point = 11.5 mL = 0.0115 L

Number of moles of KOH added at half-equivalence point = Molarity x Volume

= 0.108 M x 0.0115 L

= 0.00124 moles

Concentration of acid at half-equivalence point = Number of moles of acid remaining ÷ Volume of acid

= (0.431 g - (0.00124 moles x 56.1 g/mol)) ÷ 0.025 L

= 0.017 M

Concentration of conjugate base at half-equivalence point = Number of moles of KOH added ÷ Volume of KOH

= 0.00124 moles ÷ 0.0115 L

= 0.108 M

pKa = pH + log([conjugate base] ÷ [acid])

= 7.08 + log(0.108 ÷ 0.017)

= 4.97

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Answer:

B. It is hard to change the temperature of the substance

125.4 kJ of heat is absorbed in the process of making 0.887 mol of CF₄.

The given reaction produces one mole of CF₄, and its enthalpy change is 141.3 kJ/mol. Therefore, the enthalpy change for the production of 0.887 mol of CF₄ can be calculated as follows:

Enthalpy change for 1 mol of CF₄ = 141.3 kJ/mol

Enthalpy change for 0.887 mol of CF₄ = (0.887 mol) x (141.3 kJ/mol)

Enthalpy change for 0.887 mol of CF₄ = 125.39 kJ

Therefore, the quantity of heat absorbed in the process of making 0.887 mol of CF₄ is 125.39 kJ.

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We can see that an atom with 14 protons, 14 neutrons, and 16 electrons is unstable, and has a -2 charge.

So the correct option is the third one.

An atom with 14 protons, 14 neutrons, and 16 electrons is not stable. The number of protons in an atom, also known as its atomic number, determines its element and its chemical properties. In this case, the atom has 14 protons, which corresponds to the element silicon (Si) on the periodic table.

For an atom to be stable, it should have a balanced number of protons and electrons. Electrons are negatively charged particles that orbit the nucleus of an atom in energy levels or electron shells. The number of electrons in a stable atom should be equal to the number of protons, resulting in a neutral charge overall.

In this case, the atom has 14 protons and 16 electrons, which means it has two more electrons than protons, resulting in a net charge of -2. This is an example of an ion.

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The balanced equation for the breakdown of solid ammonium hydroxide into gaseous ammonia and liquid water is:

[tex]NH_{4} OH[/tex](s) → [tex]NH_{3}[/tex] (g) + [tex]H_{2}O[/tex] (l)

This equation indicates that one molecule of solid ammonium hydroxide ([tex]NH_{4} OH[/tex]) decomposes to form one molecule of gaseous ammonia ([tex]NH_{3}[/tex]) and one molecule of liquid water ([tex]H_{2}O[/tex]).

The type of reaction that is occurring is a decomposition reaction. This is because one compound, ammonium hydroxide, is breaking down into two simpler substances, ammonia and water. Decomposition reactions can be induced by heat, light, or electricity and are a common type of chemical reaction in nature. In this case, the breakdown of ammonium hydroxide is likely to be endothermic since heat is required to break the bonds within the compound.

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To measure reaction heat under isochoric conditions, a bomb calorimeter is needed.

This device is designed to maintain a constant volume (isochoric) during the reaction, allowing for accurate measurement of reaction heat. To improve the accuracy of the coffee cup calorimeter for measuring reaction heat under isobaric conditions, a modification that could be made is to use a stirring device to ensure uniform mixing of the reactants and to minimize heat loss to the surroundings.

Additionally, a lid with a small hole could be placed over the top of the calorimeter to prevent heat loss while still allowing for pressure equalization. These modifications would help to minimize errors in heat measurement and improve the accuracy of the results obtained.

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The answer is 1ml. The answer is 1ml because of calibration of this graduated cylinder

Answer:

1 mL

Explanation:

According to your definition, it is the difference between marked spaces divided by the # of spaces between marked values.

Difference between 2 marked values: 5 mL

# Of Spaces between marked values: 5

Calibration: 5 mL / 5 mL = 1 mL

Weight percentage of KClO₃ is 117% indicates that there could have been a mistake in the experiment.

First, calculate the partial pressure of O₂ in the flask, which is equal to the total pressure minus the vapor pressure of water:

Partial pressure of O₂ = 749 torr - 16.5 torr = 732.5 torr

Next, calculate the number of moles of O₂ produced from the decomposition of KClO₃. We can use the ideal gas law to do this:

PV = nRT

n = PV/RT

where P is the partial pressure of O₂, V is the volume of O₂ collected over water (in liters), R is the gas constant (0.08206 L atm mol⁻¹ K⁻¹), and T is the temperature in Kelvin (273.15 + 19 = 292.15 K).

n = (732.5 torr / 760 torr/atm) × (0.260 L / 1000 L) × (0.08206 L atm mol⁻¹ K⁻¹) × (292.15 K)⁻¹

n = 0.00966 mol O₂

From the balanced chemical equation, 2 moles of KClO₃ produces 3 moles of O₂. Therefore, the number of moles of KClO₃ in the sample is:

n(KClO₃) = (3/2) × n(O₂)

n(KClO₃) = (3/2) × 0.00966 mol

n(KClO₃) = 0.0145 mol

Finally, use the formula for weight percentage:

Weight percentage of KClO₃ = (mass of KClO₃ / mass of sample) × 100%

Calculate the mass of KClO₃ from the number of moles using the formula:

mass = n × formula weight

mass(KClO₃) = 0.0145 mol × 122.55 g/mol

mass(KClO₃) = 1.77 g

The mass of the sample is given as 1.515 g, so the weight percentage of KClO₃ is:

Weight percentage of KClO₃ = (1.77 g / 1.515 g) × 100%

Weight percentage of KClO₃ = 117% (This result is not physically meaningful, indicating that there may have been an error in the experiment.)

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Dipolar molecules have a separation of charge with a positive center and a negative center located at two different points, resulting in a net dipole moment. The correct option is true

Dipolar molecules are molecules that have a separation of charge, resulting in a positive center and a negative center located at two different points in the molecule.

This separation of charge creates a net dipole moment, which is a measure of the molecule's polarity. The magnitude and direction of the dipole moment depend on the difference in electronegativity between the atoms in the molecule and the molecule's geometry.

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In the year 2000, the population of Arctic foxes reached its peak.

A region's population is the total number of people living there. Typically, it is expressed as the number of persons in a given volume or region. A census is typically performed to estimate population in order to ascertain its size, density, and distribution. The term "population" can also refer to the variety of species present in a region. Population growth is the gradual rise in a species' number of individuals in a particular area.

At that time, the total number of Arctic foxes in their habitat, which stretches from northern Europe and Asia over the tundra of the Arctic Circle, was believed to be 745,000. Based on the International Union for Conservation of Nature's most recent estimations, this population figure.

The Arctic fox is a very tough species that can endure some of the world's harshest environments. They can also adjust to their surroundings and eat a range of foods, such as grass, eggs, carrion, small mammals, and carrion.

Unfortunately, a variety of causes are causing the Arctic fox population to decline at the moment. Additionally, human actions like hunting, habitat loss, and fur trapping are lowering their numbers.

The Arctic fox is not now facing extinction, according to the IUCN, which has classified it as a species of Least Concern. However, the species is threatened by a number of factors, and unless conservation efforts are made, its population is likely to keep declining.

Reducing human influences on the Arctic fox's environment is crucial for its protection. This entails restricting hunting and trapping in addition to minimising habitat loss and pollution. The ability of the species to adapt to climate change should also be improved, and their population numbers and trends should be tracked. If these steps are adopted, the number of Arctic foxes may eventually return to its original high.

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The complete question is,

Which year saw the highest arctic fox population? How many people attended?

The balanced chemical equation for the reaction between Fe2+ and MnO4- in acidic solution is :

5 Fe2+ + MnO4- + 8 H+ -> 5 Fe3+ + Mn2+ + 4 H2O

From the equation, we can see that 1 mole of MnO4- reacts with 5 moles of Fe2+.

The initial moles of Fe2+ in the solution are :

0.500 mol/L x 0.100 L = 0.050 mol

Since the stoichiometric ratio between MnO4- and Fe2+ is 1:5, the moles of MnO4- required to react with all the Fe2+ are :

5 x 0.050 mol = 0.250 mol

Therefore, the quantity of Fe2+ ion reacting, in moles, is 0.050 mol.

C4H10 + O2 --> CO2 + H2O

The mass must be balanced:

2C4H10 + 13O2 --> 8CO2 + 10H2O

The molar mass of butane is 12 × 4 + 10 = 58

The molar mass of carbon dioxide is 16 × 2 + 12 = 44

First, we calculate the moles of carbon dioxide produced

[tex]n_{CO2} = \frac{50,0 g}{44 g/mol} = 1,14 mol[/tex]

If 2 moles of butane are needed for produce 8 moles of CO2 then x moles of butane are needed to produce 1,14 moles of CO2, therefore

[tex]\frac{2}{8} = \frac{x}{1,14} \\ \\ x = \frac{1,14}{4} = 0,285 mol[/tex]

Then the moles can be multiplied by the molar mass of butane in order to get the total mass of butane burned.

[tex]m_{C4H10} = 0,285 mol × 58 g/mol = 1,65 g[/tex]

Explanation:

The molar mass of octane (C8H18) is approximately 114 g/mol.

To find the energy required to increase 1 mole of substance by 10°C, we can use the formula:

ΔE = n * C * ΔT

where ΔE is the energy required, n is the number of moles, C is the specific heat, and ΔT is the change in temperature.

For water, n = 1 mol, C = 4.184 J/gK, and ΔT = 10°C.

So, the energy required to increase 1 mole of water by 10°C is:

ΔE_water = n * C_water * ΔT

= 1 mol * 4.184 J/gK * 10 K

= 41.84 J

For octane, n = 1 mol, C = 2.22 J/gK, and ΔT = 10°C.

So, the energy required to increase 1 mole of octane by 10°C is:

ΔE_octane = n * C_octane * ΔT

= 1 mol * 2.22 J/gK * 10 K

= 22.2 J

Therefore, it takes more energy to increase 1 mole of water by 10°C than 1 mole of octane.

Okay, here are the key points to consider:

- Crude oil is separated into various components like gasoline, diesel fuel, jet fuel, bitumen, etc.

- A barrel of oil contains 22% gasoline and 38% diesel fuel. So these components make up a major portion of the oil.

- When the price of a barrel of oil increases, the costs to produce these components like gasoline and diesel also go up.

- So the prices of gasoline, diesel fuel and other components are directly linked to the price of crude oil. They will likely increase proportionally if oil price rises.

- Bitumen may be affected in supply but its price could still adjust based on supply and demand. It's linked to oil price indirectly.

- Diesel fuel price will also likely rise with oil price increase. It cannot be produced just from ethanol. It requires crude oil.

- Jet fuel price will also follow the increase in oil price. It's not inverse.

So among the options, the choice that is most accurate is:

The price of gasoline will increase in direct proportion to the increase in a barrel of oil.

The other options are not fully supported. Diesel and jet fuel prices will rise, bitumen may see some supply impact but prices will adjust, and prices are directly linked to oil prices, not inversely.

Let me know if you need more explanation.

Answer:

Pressure of the gas =766.4 mmHg.

Explanation:

Gas pressure greater than atmospheric pressure = Atmospheric pressure + Height

745.0 mm + 26.4 cm = 766.4 mmHg.

The kJ of the energy absorbed for the every mole of the carbon reacted is 104.8 kJ.

The chemical equation is as :

2C + 2H ---> C₂H₄   ,     ΔH = + 52.4 kJ/mol

The ΔH is the enthalpy change that is determined by the subtracting the energy of the reactants to the products.

The  ΔH = energy of the products - energy of the reactants

The expression for the energy is as :

q = n ΔH

Where,

n = number of the moles

ΔH = enthalpy change

The kJ of the energy absorbed for the every mole of the carbon reacted :

q = 2 mol × 52.4 kJ/mol

q = 104.8 kJ

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An increase in the internal energy of a system can be caused by several factors, such as heating, compression, and work done on the system.

In general, any process that adds energy to a system will result in an increase in its internal energy. For example, if heat is added to a gas in a closed container, the gas molecules will start moving faster and colliding more frequently, resulting in an increase in the internal energy of the gas.

Similarly, if work is done on a system, such as by compressing a gas, the internal energy of the gas will increase due to the increased kinetic energy of its molecules.

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The enthalpy of vaporization of ethanol is 38.56 kJ/mol at its boiling point (78°C). Calculate the value of entropy of  surrounding when 1.00 mole of ethanol is vaporized at 78°C and 1.00 atm is -110.2 kJ/mol K. The correct option is option A.

Entropy is the measurement of the amount of thermal energy for each degree of temperature in a system that cannot be used for productive work. Entropy is a measure of a system's molecular disorder or unpredictability since work is produced by organised molecular motion.

Entropy theory offers profound understanding of the pattern of impulsive shifts for numerous commonplace events. A standout of 19th-century physics is its invention by the German scientist Rudolf Clausius in 1850.

C[tex]_2[/tex]H[tex]_5[/tex]OH(l)   →  C[tex]_2[/tex]H[tex]_5[/tex]OH(g)    

ΔSsystem= 38.56 /351

                  =110.2 kJ/mol K

ΔSsurrounding=-110.2 kJ/mol K

ΔSuniverse=0

Therefore, the correct option is option A.

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The packing efficiency (in %) of the resultant solid is (d) 75.

Packing efficiency of a crystal lattice refers to the percentage of space in a given volume that is occupied by atoms, ions, or molecules in the lattice.

The closest packing efficiency of a crystal lattice is given by the formula:

packing efficiency = (number of atoms in the unit cell x volume of each atom) / volume of the unit cell

For an fcc lattice, the number of atoms in the unit cell is 4, and for an alternate tetrahedral void, the number of atoms is 2. Therefore, the total number of atoms in the unit cell is 4 + 2 = 6.

The packing efficiency of fcc is 74%, which means the volume occupied by the atoms is 74% of the total volume of the unit cell. When the alternate tetrahedral voids are filled with atoms, the total number of atoms increases, and the volume occupied by the atoms also increases. Hence, the packing efficiency will be greater than 74%.

The closest option to the calculated value is (d) 75. Therefore, the answer is (d) 75.

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Using the equation q = mcT, where q is the amount of heat energy released (0.0501 kJ), m is the sample's mass (0.5 g), c is the specific heat of liquid water (4.184 J/g-°C), and T is the temperature change, one can determine the anticipated temperature change for a 0.5 gramme sample of water that releases 0.0501 kJ of heat energy.

T = q / (mc) is the result of rearranging the equation. We calculate T = 0.0501 kJ / (0.5 g * 4.184 J/g-°C) = 0.6022 °C by plugging in the given variables.

As a result, a 0.5 gramme sample of water that releases 0.0501 kJ of heat energy should have an estimated temperature change of 0.6022 °C.

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1) New plants start to grow and sprout: As temperatures warm up in the spring, seeds that have been dormant over the winter start to germinate and new plants start to grow.

Sprout is a type of plant that is grown from a seed. It is usually a young plant that has just started to grow, and is usually eaten raw or lightly cooked. Some of the most common sprouts are alfalfa, broccoli, and mung bean. Sprouts are highly nutritious, as they contain a large amount of vitamins, minerals, protein, and antioxidants. They are a great addition to salads, sandwiches, and stir-fries, and can also be used as a topping for soups or curries. Sprouts are easy to grow at home, and can be enjoyed in a variety of dishes.

2) The leaves on trees start to change colors: As temperatures warm up in the spring, deciduous trees start to produce new leaves that are lighter in color than the leaves they had in the fall.

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Breaking tension describes this circumstance. Tensiometers function up to 0.5 bar. The vacuum gauge of the majority of commercial tensiometers has a suction scale that ranges from 0 to 100 cb.

A tube filled with water and fitted with a specific porous tip and vacuum gauge is a tensiometer. This device monitors soil water suction, which is akin to the method a plant root employs to get water from the ground. upkeep of the field as seen to the right. Tensiometers are reusable and not very expensive.

In comparison to ECH2O-5TE and Watermark without site-specific calibration, Tensiometer gave relatively reliable soil moisture measurements, according to statistical analysis of the results. Watermark overestimated the water content of the soil, while ECH2O-5TE did not.

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The reaction in the experiment is exothermic reaction and 158.72 kilo joules at 34.51 degrees celsius is released.

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