EXPERIMENT EIGHT In Mohr's method, chloride is titrated with a silver nitrate solution. A soluble chromate salt is added as DETERMINATION OF CHLORIDE BY THE MOHR METHOD PRINCIPLE the indicator. When the precipitation of the chlorine is complete, the first excess of silver ions react with chromate to form a red precipitate of silver chromate: Ag + C → AgCl(s) (Titrating reaction) (AgNO₂) (White) 2Ag + CO² → Ag-CO(S) (End-point reaction) (red) Titrant added near the equivalent point cause local excesses of silver ions that result in flashes of red colour, but the correct end point is the first permanent darkening of the yellow chromate colour. The end-point is not as sharp as might be desired. Some excess silver nitrate must be added to form enough silvery chromate to be seen over the heavy white precipitate and yellow chromate solution. This makes it necessary to determine an indicator blank, the volume of which is subtracted from the volume of silver nitrate used in titrating the sample. The concentration of chromate indicator is important. If too much chromate is added, the end-point occurs before the equivalence point; if not enough, the end-point come late (Why?). Acidity is important in the Mohr titration. In acidic solutions, part of the indicator is present as HCO, instead of CrO2; hence, more indicator is needed to form a silver chromate precipitate. About pH 8 is ideal for the titration. Sodium Carbonate will buffer the solution of about this pH. With more alkaline solutions, there is danger of precipitating some silvery carbonate of silver hydroxide. PROCEDURE Dry the NaCl for 1 hour at 100-1100C, Carefully, weight 0.25g and 0.35g samples. Dissolve each in about 100cm' of water. Add a pinch of calcium carbonate or sodium hydrogen carbonate, making further additions if necessary, until effervescences ceases. Then introduce 1 to 2 cm³ of 5% potassium chronmate, and titrate with standard silver nitrate solution to the first permanent appearance of a buff colour due to silver chromate. Determine an indicator blank by suspending the small quantity of calcium carbonate in about 100cm' of water containing 1 to 2cm³ of 5% potassium chronmate. Use the colour developed in this determination as a standard for judgement of the end-point in the actual titration.​

The rate at which water molecules gain kinetic energy and escape the liquid phase into a gaseous phase increases as the temperature increases.

In detail, when water is heated, the molecules absorb the energy and start to vibrate more and more vigorously. If the water is heated to its boiling point, 100°C, the molecules have gained enough kinetic energy to escape the liquid phase and transition into a gaseous phase (steam).

This process of a substance changing from a liquid to a gas is called boiling or evaporation. As the temperature of water continues to increase, the rate at which molecules escape the liquid phase also increases, leading to an increase in the rate of boiling or evaporation.

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Answer:

5 points are mine

.....................................

Option C is correct. The right response is 1.4. The Henderson-Hasselbalch equation is written as pH=pKa +log([A][HA])

A weak base will react with the H+ from a strong acid to create the weak acid HA when a strong acid is put to a buffer: H+ + A- HA. The pH only minimally changes because the H+ is absorbed by the A- rather than forming H3O+ (H+) by interacting with water. pH is calculated as follows: pH = pKa + log [Salt] / [Acid]. Any acidic buffer solution will always have a pH below 7, while any basic buffer solution will always have a pH above 7. Option C is correct.

The right response is 1.4.

The Henderson-Hasselbalch equation is written as pH=pKa+log([A][HA])

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To calculate the percent methyl yield, we need to divide the amount of product obtained by the amount of theoretical yield, then multiply by 100.

Theoretical yield = 102 mg

Actual yield = 87 mg

Percent yield = (Actual yield / Theoretical yield) * 100

Percent yield = (87 / 102) * 100 = 85.3

So the Methyl is : 85.3

Methyl is a hydrophobic alkyl functional group. Its name is derived from methane, a simple alkane compound. Methyl is methane which has lost a hydrogen atom, making it unstable and reactive. Its chemical formula is -CH₃. This group occurs frequently in many organic compounds.

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The NaOH given to the student should weigh 46.3 grams.

The formula units can be calculated as moles multiplied by the Avogadro number.

Avogadro number is, 6.023 × 10^23.

The formula units are given to be 7.03 × 10^23.

Formula units = Avogadro Number × Number of moles

7.03 × 10^23 = 6.023 × 10^23 × Number of moles

Number of moles = (7.03 × 10^23)/(6.033 × 10^23)

Number of moles = 1.16

One mole of NaOH has the mass 39.99 grams.

1.16 moles of NaOH has mass = 1.16 × 39.99 grams.

= 46.38 grams.

Hence, the NaOH should weigh 46.3 grams.

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The mass percent of an element says how much gram of it is present in 100 g of the compound. Hence, the total percent is 100. Therefore, if the mass percent of Zn is 35.7, then the mass percent of oxygen is 64.3%.

The percentage composition of an element in a compound is the ratio of its mass to the total mass of the compound multiplied by 100. It is  common term to expresses the concentration and composition of constituent elements in a compound.

35.7 % of Zn in a compound of zinc and oxygen means, 35.7 g of zinc is present in 100 g of the compound. It is said that only Zn and oxygen is present in the compound.

Thus, mass percent of oxygen = 100 -35.7 = 64.3%.

Therefore, the percentage composition of oxygen in the compound is 64.3%.

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The nitrate anion must have 6 additional electrons, making it a negative ion with a total of 32 electrons.

In the Lewis structure of the nitrate anion, NO3–, the central nitrogen atom is surrounded by three oxygen atoms and is connected to them with single covalent bonds. If each atom is to obey the octet rule, then the nitrogen atom must have 8 valence electrons, and each of the oxygen atoms must have 6 valence electrons. This means that the nitrate anion must have a total of 8 + 3×6 = 26 valence electrons. The nitrate anion must also have a total of 8 + 3×8 = 32 electrons when considering the octet rule for the oxygen atoms. As a result, the nitrate anion must have 6 additional electrons, making it a negative ion with a total of 32 electrons.

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Complete question:

What is the Lewis structure of the nitrate anion, NO3–, if all atoms obey the octet rule?

The amount of heat needed to boil the given mass of acetic acid is 72.212 kJ.

Based on the provided information,

The mass of acetic acid = 120 g

The number of moles of acetic acid = Mass of acetic acid/molar mass of acetic acid

The molar mass of acetic acid = 60.052 g/mol

Hence,

The number of moles of acetic acid = 120/60.052 = 1.998 moles

The initial temperature of acetic acid = 16.7 °C = 16.7 + 273.15 = 289.85 K

The standard boiling temperature of acetic acid = 118.1 °C = 118.1 + 273.15 = 391.25 K

The change in temperature of acetic acid ΔT = 391.25 – 289.85 = 101.4 K

The enthalpy of vaporization of acetic acid ΔH = 23.7kJ/mol

The heat capacity of acetic acid c = 2.043 J/g.K

The amount of heat needed to increase the temperature from 16.7 ° C to boiling point is:

q = mcΔT = 120*2.043*101.4 = 24.859 kJ

The amount of heat need for the given mass,

q = ΔH*number of moles = 23.7*1.998 = 47.353 kJ

Hence, the total amount of heat needed to boil the given mass of acetic acid = 24.859 + 47.353 = 72.212 kJ

Note: The question is incomplete. The complete question probably is: Calculate the amount of heat needed to boil 120.g of acetic acid (HCH3CO2), beginning from a temperature of 16.7°C.

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When 50g of solid carbon dioxide (dry ice) sublimes, 28.6kj of heat are required. To produce 57g of carbon dioxide gas from the sublimation of dry ice, you would need approximately 40.4kj of heat.

The calculation of the amount of heat required to produce 57g of carbon dioxide gas from the sublimation of dry ice can be done by using the heat of sublimation. The heat of sublimation is the amount of energy required to turn a substance from a solid to a gas. In this case, the heat of sublimation for carbon dioxide (dry ice) is 28.6kj/mol. Since 1 mol is equal to 44.01g, then 28.6kj/mol is equal to 0.652kj/g. To calculate the amount of heat required to produce 57g of CO2 from the sublimation of dry ice, we can multiply 0.652kj/g by 57g, which gives us a total of 40.4kj of heat.

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1 mole of Sulfuric acid reacts with 2 moles sodium hydroxide to give 1 mole of sodium sulfate and 2 moles of water. Here the concentration of H₂SO₄ used is 0.035 M.

The balanced equation for the reaction is

H₂SO₄ + 2NaOH ⇒ Na₂SO₄ + 2H₂O

So 1 mole of sulfuric acid reacts with 2 moles of sodium hydroxide to give one mole of sodium sulphate and two moles of water.

Here 6.8 ml of 6 M sodium hydroxide is reacted.

Molarity = number of moles/volume in L

         6 = n/ 0.0068 L

n = 6 × 0.0068 = 0.0408 moles.

So, number of moles of H₂SO₄ reacted =

Number of moles of NaOH/2 = 0.0408/2 = 0.0204

Concentration = number of moles/ Volume in L

                                                 = 0.0204/ 0.6 =0.035M.

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Ion's equilibrium potential is defined as the state in which the tendency of ions (electrically charged particles) to flow across a cell membrane from regions of high concentration is exactly balanced by the opposing potential difference (electric charge) present across the membrane.

In other words it is also defined as the electrical potential difference across the cell membrane that exactly balances the concentration gradient for an ion.

The other widely used name of equilibrium potential is  called the Nernst potential, after Walther Nernst, a German physical chemist who, in the late 19th century, developed equations for calculating the electrical potential at which there is no longer a net flux of a specific ion across a membrane.

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The core atom is typically the atom with the smallest subscript in the molecular formula and the atom with the greatest bonding capacity.

If all of the atoms normally make the same amount of bonds, the central atom is usually the least electronegative atom.

Consider the atoms' bonding patterns: Because of its four bonds, carbon is always a central atom. Oxygen often forms two bonds as well as two lone pairs.

Because hydrogen has just two electrons in its valence shell and hence can only make one bond, it can never be the center atom.

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Convection currents are the underlying cause of tectonic plate interactions that cause geological events, like earthquakes and volcanoes.

The tectonic plate interactions and processes that result in the construction of mountains and other landforms constitute the geological event that is taking place. Convection currents, which happen as molten rock rises from the Earth's mantle below the surface and then cools as it flows to the surface, are one of the primary processes generating this creation.

The plates move and interact with one another as a result of this process, which is fueled by the disparity in density between the hot and cold rock. Divergent boundaries, the kind of boundary at which this phenomenon occurs, are brought about by two plates moving apart.

The creation of the Himalayan Mountains is an illustration of this process. The Himalayas were created as a result of the Himalayan Plate colliding with the Eurasian Plate as it steadily moved north.

High peaks, deep valleys, and steep cliffs are some of the physical features that are visible as a result of this process. The highest mountain range in the world is the Himalayas, and Mount Everest is its highest peak.

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Answer:

To determine the mass of an object that has a volume of 23.0 ml and a density of 0.788 g/cm3, we can use the equation:

mass = density x volume

First, we need to convert the volume from milliliters to cubic centimeters (cm^3) since the density is given in g/cm^3.

1 mL = 1 cm^3

so

volume = 23.0 ml = 23.0 cm^3

Next, we can substitute the density and volume into the equation above:

mass = 0.788 g/cm^3 x 23.0 cm^3 = 18.204 g

Therefore, the mass of the object is 18.204 grams.

The density of the metal is 1 g/ml.

To calculate the density of the metal, we need to determine the mass and volume of the metal. If the water level in the graduated cylinder rose to 60 ml after adding the metal pellets.

We can assume that the volume of the metal is equal to the volume of water displaced, which is 60 ml. We can then use the equation of density, which is:

density = mass/volume

Since the volume is known (60 ml), to find the mass we can use the conversion factor: 1 ml of water has a mass of 1 g.

So, the mass of the metal is 60 g.

Now we can substitute the mass and volume into the equation for density:

density = 60 g / 60 ml = 1 g/ml

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Lazzaro Spallanzani concluded that boiling the broth killed any potential living organisms and that air was not necessary for life, based on the results of his experiments boiling broths and sealing the flasks.

Lazzaro Spallanzani was an Italian scientist who lived in the late 18th century. In his experiments, he boiled broths for extended periods of time and then sealed the flasks by melting their glass necks closed. By doing this, he aimed to determine the conditions necessary for life to exist.

The results of his experiments showed that boiling the broth killed any potential living organisms and that the broth did not contain any new microorganisms after being sealed and boiled. This led Spallanzani to conclude that air was not necessary for life and that life could not arise spontaneously from non-living matter.

These findings were crucial in disproving the then-prevailing idea of spontaneous generation, which was the belief that life could arise spontaneously from non-living matter. Spallanzani's experiments paved the way for further advancements in microbiology and the understanding of the origins of life.

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Medium fresh orange because  in a medium fresh orange only contains 0-3 mg sodium (Alternative B).

Sodium is a type of mineral that you can easily find in various foods, especially salt. Salt itself is known as sodium chloride and is the most abundant source of sodium, up to 40% with the remainder consisting of chloride.

People use salt as a flavor enhancer so that food is not bland. Salt also functions as a binder for food components as well as a stabilizer and food preservative.

a. one cup of canned vegetable soup. On average, canned soup has 700 mg of sodium.

b.a medium fresh orange. sodium in a medium fresh orange only contains 0-3 mg of sodium.

c. 4-ounces of 100 percent tomato juice contain about 1200 mg of sodium.

d. hotdogs. a hotdog contains about 1250 mg of sodium.

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The amount of water  that is produced is 3.46 moles of water.

We have to note that we have to apply the stoichiometry of the reaction so that we can be able to get the amount of the water that can be produced in the reaction.

We know that the reaction is; 2H2 + O2 ---->2H2O

Number of moles of the oxygen = 55.44 grams/32 g/mol

= 1.73 moles

If 1 mole of oxygen produces 2 moles of water

1.73 moles of oxygen would produce 1.73 * 2/1

= 3.46 moles of water.

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The third law of thermodynamics will allow by the absolute entropies of the substances to be determined by a reference point by which entropy will changes can be measured and assigned an absolute entropy for the substance.

The third law of thermodynamics states that the entropy of an system approaches a constant value as the temperature approaches absolute zero. The entropy of a system at absolute zero is typically zero, and in all the cases it is determined only by the number of different ground states it has.

Consequences: It defines the sign of the entropy of any of the substance at temperatures above absolute zero as positive, and it provides a fixed reference point that allows us to measure the absolute entropy of any of the substance at any temperature.

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C. The theoretical yield of aspirin is found to be 4.2g

The largest amount of product that could be generated from the provided reactant amounts is termed as the theoretical yield. The quantity of product that actually formed during the reaction in a laboratory environment is known as the actual yield.

C₇H₆O₃ + C₄H₆O₃→ C₉H₈O₄ ( aspirin)

No of moles of  salicylic acid => 3.2/138.122 => 0.023 mol

no of moles of acetic anhydride => 1.08 g/mL x 6.3 mL / 102.089 g/mol

                                                        => 0.066mol

salicylic acid is limiting reagent

Theoretical yield calculated:

1 mole of salicylic acid=> 1 mole of aspirin

      Hence,  0.023  mol of aspirin formed in this reaction.

Theorectical yield of aspirin =>  0.023 mol x 180g/mol => 4.2g

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The total pressure in the flask is determined by the ideal gas law which is 4.00 atm.

This law states that the pressure of a gas is equal to its number of moles times its temperature divided by its volume. For this question, we need to calculate the number of moles of each gas before the reaction.

Methane has a molar mass of 16.04 g/mol, so 177 mL of methane would be 1.106 moles. Chlorine has a molar mass of 35.45 g/mol, so 911 mL of chlorine would be 2.587 moles. Thus, the total number of moles in the flask is 3.693.

Next, we need to calculate the number of moles that have reacted. 72.5% of the reaction has been completed, so 0.725 moles of the 3.693 moles have reacted.

Finally, the total pressure in the flask is equal to the number of moles times the temperature divided by the volume. This gives a pressure of 4.00 atm.

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A chemical reaction typically produces 4.55 g of NaOH. The percent yield if the reaction could theoretically produce 5.00 g would be 91 %

Theoretical yield is the amount of a product that results from the complete conversion of the limiting reactant in a chemical reaction.

The actual yield is calculated as the theoretical yield multiplied by 100 to get the percent yield. the formula will be:

percent yield = ( experimental yield / theoretical yield ) × 100 %

The theoretical yield of the reaction = 5 g

mass of the NaOH produced = 4.55 g

the percent yield = ( experimental yield / theoretical yield ) × 100 %

                             = ( 4.55 g  / 5 ) ×100 %

                             = 91 %

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The molality of a 2.89 mass aqueous solution of sodium chloride is 0.0494 mol/kg .

Molality is a measure of the concentration of a solute in a solution, expressed as the number of moles of solute per kilogram of solvent. It is a unit of concentration that is useful in calculations involving solutions with non-ideal properties. Molality is related to molarity, which is the number of moles of solute per liter of solution. The difference between the two is that molarity takes the volume of the solution into account, while molality does not.

The molality can be calculated using the equation: molality = (mass of solute / volume of solution) / molar mass of solute. In this case, the mass of solute is 2.89 g, the volume of the solution is 1 mL, and the molar mass of sodium chloride is 58.44 g/mol. Plugging these values into the equation, we get molality = (2.89 g / 1 mL) / 58.44 g/mol = 0.0494 mol/kg. Therefore, the molality of the 2.89 mass aqueous solution of sodium chloride is 0.0494 mol/kg.

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Biodiversity is the number & variety of species that are present in an area.

The definition of diversity of flora and fauna (biodiversity) is the variability among living things from all sources, including the interactions of terrestrial, coastal and marine ecosystems and other aquatic ecosystems and the ecological complexes in which living things live as a part. This includes species diversity, between species and ecosystems.

In another sense, diversity of flora and fauna is the availability of diversity of biological resources in the form of types and richness of germplasm (genetic diversity within species), diversity between species and diversity of ecosystems.

Biodiversity is all life on this earth including plants, animals, fungi and microorganisms as well as the various genetic materials they contain and the diversity of the ecological systems in which they live. This includes the relative abundance and genetic diversity of organisms from all habitats, whether on land, sea or other aquatic systems.

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Sodium hypochlorite (NaClO) should be added slowly to borenol because the reaction between sodium hypochlorite and borenol is exothermic and releases heat. If the sodium hypochlorite is added too quickly, the reaction will become very exothermic and generate a lot of heat, which could cause the reaction mixture to boil over or even explode.

By adding the sodium hypochlorite slowly, the heat generated by the reaction is dissipated gradually, preventing an uncontrolled release of energy. This helps to ensure the reaction proceeds smoothly and safely. Additionally, by adding the sodium hypochlorite slowly, the reaction can be controlled more easily, which can lead to a more efficient and complete reaction.

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The atomic mass of copper is 63.546 amu. This can be found on the periodic table. The molecular mass of bromophenol blue is 669.9607 g/mol.

Bromophenol blue is a dye made of copper and bromine, which can be used as an indicator in acid-base titrations. Its molecular formula is CuBr2, meaning that it has two atoms of bromine and one atom of copper.

The atomic mass of copper is 63.546 amu, and the atomic mass of bromine is 79.904 amu. Therefore, the molecular mass of bromophenol blue is 669.9607 g/mol (63.546 + 79.904 * 2). This means that for every mole of bromophenol blue, we have 669.9607 grams.

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Circle b represents the solution after 300 mL of solvent has been added.

Volume percent = {Volume of solute / volume of solution} x 100

After adding the solution, the volume of solution increases but volume of solute remains the same. For same volume of solute, the volume percent is high for once which has the volume of solution is low.

In 100 mL the visually represented solution has 12 balls for solute. When 300 mL of solution is added to the solute, the total volume is 400 mL volume is increased 4 times. Then 12/4 = 3 is the number of solute present in the circle. Circle b represents the solution.

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In normal-phase column chromatography, the solvent which has more eluting power is dichloromethane.  The solvent’s eluting power increases with polarity.

Normal-phase column chromatography (NPLC) refers to a separation technique where components are distributed between two phases. One phase is stationary and polar and the other is non-polar and moves in a definite direction. Hence, NPLC utilizes columns packed with polar stationary phases combined with nonpolar or moderately polar mobile phases to separate the mixture components. The rate at which solutes migrate through NPLC columns is primarily a function of their polarity.

In normal-phase column chromatography, the solvent which has more eluting power is dichloromethane as it is more polar. The eluting power of a solvent refers to a measure of how well the solvent can pull an analyte off the adsorbent to which it is attached. Dichloromethane molecules will attract the polar molecules and elute them from the column.

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It takes 34.1 minutes to evaporate 3 kg of water at 100°C using the element.

The heating element's current draw is I=15 A.

V=220 V is the supply voltage.

The water's mass, m=3 kg

The water's temperature is T=100 °C.

Water's latent heat of vaporization, L v, is 2.25 106 J/kg.

The heating element's power is provided by,

P = IV =Wt

where W is the amount of labor the heating element does to evaporate the water, and t is the amount of time it takes.

Regarding arranging,

t=W/IV

The work carried out on the water and by the heater is identical. Additionally, the effort expended to evaporate the specified amount of water is equivalent to that effort.

i.e.,

W = mL/IV

Therefore,

t = mL/IV

The time will be in seconds because all the values are in SI units.

Thus, the amount of time in minutes it takes for the water to evaporate is given by,

t = mL/IV x 60

Using the known values as a substitute

t = (3 x 2.25 x 10⁶) / (15 x 220 x 60)

Therefore, it takes 34.1 minutes to evaporate the specified volume of water.

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if you spill a chemical on the floor or bench, you should notify your teaching assistant and obtain the proper clean-up procedure.

The compounds are very risky. They are poisonous when inhaled and will result in serious burns. Additionally, if preparation steps are carried out improperly, there is a chance of explosion.

Please create, read, and sign risk assessments for each process before beginning any work. For each chemical, create, read, and sign COSHH forms. If your lab has never used these procedures before, let your safety officer know.

Have someone demonstrate the procedure first, if at all feasible. Work in a functional fume hood at all times, and only prepare the necessary amount of acid. Put on a lab coat, safety glasses, and butyl gloves.

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