7.66 Write balanced equations for the following reactions: (a) potassium oxide with water, (b) diphosphorus trioxide with water, (c) chromium(III) oxide with dilute hydrochloric acid, (d) selenium dioxide with aqueous potassium hydroxide

Answer: Chipless RFID tags

Final answer:

To calculate the percent by mass of calcium carbonate in the sample, we need to determine the mass of calcium carbonate present in the 1.14 L of carbon dioxide produced. We can use the ideal gas law to calculate the moles of carbon dioxide, and then use stoichiometry to convert from moles of CO2 to moles of CaCO3. Finally, we can calculate the percent by mass of CaCO3 in the sample by dividing the mass of CaCO3 by the mass of the sample and multiplying by 100.

Explanation:

To calculate the percent by mass of calcium carbonate in the sample, we need to determine the mass of calcium carbonate present in the 1.14 L of carbon dioxide produced. We can use the ideal gas law to calculate the moles of carbon dioxide, and then use stoichiometry to convert from moles of CO2 to moles of CaCO3. Finally, we can calculate the percent by mass of CaCO3 in the sample by dividing the mass of CaCO3 by the mass of the sample and multiplying by 100.

First, let's calculate the moles of CO2 using the ideal gas law:

mass of CO2 = (volume of CO2) x (molar mass of CO2) = (1.14 L) x (22.4 g/mol) = 25.536 g

Next, let's calculate the moles of CaCO3 using stoichiometry. From the balanced equation CaCO3 + 2HCl → CaCl2 + H2O + CO2, we know that 1 mole of CaCO3 produces 1 mole of CO2. Therefore, moles of CaCO3 = moles of CO2 = 25.536 g / (molar mass of CaCO3) = 25.536 g / 100.09 g/mol = 0.255 mol

Finally, let's calculate the percent by mass of CaCO3:

percent by mass of CaCO3 = (mass of CaCO3 / mass of the sample) x 100 = (0.255 mol x (100.09 g/mol)) / 5.28 g x 100 = 4.85%

Answer:

Newton's 2nd Law says the acceleration of an object depends on its mass and the amount of net force acting on it.

Explanation:

Definition of acceleration:

The acceleration is rate of change of velocity of an object with respect to time.

Formula:

a = Δv/Δt

a = acceleration

Δv = change in velocity

Δt = change in time

Units:

The unit of acceleration is m.s⁻².

Acceleration can also be determine through following formula,

F = m × a

a = F/m

This is the newton's second law:

"The acceleration of an object depends on its mass and the amount of net force acting on it"

The acceleration is depend directly on the force while inversely on the mass.

Answer:

Mass and Force

Explanation:

Answer:

Pyruvate dehydrogenase / Feedback on pyruvate decarboxylase production

Explanation:

In the Krebs cycle, pyruvic acid from glycolysis undergoes an oxidative decarboxylation process through the action of the pyruvate dehydrogenase enzyme found within the mitochondria of eukaryotes, it reacts with coenzyme A (CoA).

The result of this reaction is the production of acetylcoenzyme A (acetylCoA) and a carbon dioxide (CO₂) molecule.

When acetyl CoA and ATP are at high concentrations (in addition to the increased NADH / NAD⁺ ratio), pyruvate carboxylase production is stimulated.

This process will eventually generate oxalacetic acid for gluconeogenesis (conversion of pyruvate to glucose).

By increasing oxalacetic acid concentrations, pyruvate dehydrogenase is eventually inhibited by a negative feedback mechanism.

In other words, as energy levels increase, the higher the pyruvate carboxylase production, and therefore the greater the inhibition of pyruvate dehydrogenase.

Explanation:

Relation between entropy change and specific heat is as follows.

            [tex]\Delta S = C_{p} log (\frac{T_{2}}{T_{1}})[/tex]

The given data is as follows.

     mass = 500 g,         [tex]C_{p}[/tex] = 24.4 J/mol K

     [tex]T_{h}[/tex] = 500 K,          [tex]T_{c}[/tex] = 250 K               

   Mass number of copper = 63.54 g /mol

Number of moles = [tex]\frac{mass}{/text{\molar mass}}[/tex]

                                 = [tex]\frac{500}{63.54}[/tex]

                                 = 7.86 moles

Now, equating the entropy change for both the substances as follows.

     [tex]7.86 \times 24.4 \times [T_{f} - 250][/tex] = [tex]7.86 \times 24.4 \times [500 -T_{f}][/tex]

       [tex]T_{f} - 250 = 500 - T_{f}[/tex]

          [tex]2T_{f}[/tex] = 750

So,       [tex]T_{f}[/tex] = [tex]375^{o}C[/tex]

         [tex]\Delta S = C_{p} log (\frac{T_{2}}{T_{1}})[/tex]

              = [tex]24.4 log [\frac{375}{500}][/tex]

              = -3.04 J/ K mol

         [tex]\Delta S = C_{p} log (\frac{T_{2}}{T_{1}})[/tex]

                  = [tex]24.4 log [\frac{375}{250}][/tex]

                  = 4.296  J/Kmol

And, total entropy change will be as follows.

                       = 4.296 + (-3.04)

                      = 1.256 J/Kmol

Thus, we can conclude that change in entropy of block A is -3.04 J/ K mol  and change in entropy of block B is 4.296  J/Kmol.

To calculate the percent ionization in this scenario, information regarding the ionization constant of lactic acid and the pH is required. The calculation would typically use the Henderson-Hasselbalch equation, but without additional data, we cannot provide a specific answer.

The question involves the calculation of the percent ionization of a weak acid in the presence of its conjugate base. To calculate this, one would need the initial concentration of the acid, the acid ionization constant (Ka), and the concentration of the conjugate base. Generally, percent ionization is given by the ratio of the concentration of ionized acid to the initial concentration of the acid, multiplied by 100%. However, since the pH or hydronium ion concentration is not provided and the solution is a buffer system (acid with its conjugate base), the Henderson-Hasselbalch equation would typically be used to find the pH first, then the percent ionization could be calculated.

As specific values are not provided for the ionization constant of lactic acid or the pH of the solution, an accurate calculation cannot be completed without them. If these values were provided, the calculation would involve using the Henderson-Hasselbalch equation to solve for pH, determining the hydronium ion concentration, and subsequently finding the percent ionization.

Answer:

The molecules of Fe formed are 3.37 ₓ10²⁴

Explanation:

The reaction is this one:

Fe + CuSO₄ --> Cu + FeSO₄

And the ratio for the reaction is 1:1

If 5.6 moles of iron react, you will have 5.6 moles of FeSO₄. By the way, you should use NA to calculate the number of molecules.

1 mol ____ has ___ 6.02x10²³

5.6 moles _______ (5.6 x 6.02x10²³) = 3.37 ₓ10²⁴

Final answer:

The change in temperature of the calorimeter upon combusting 0.950 grams of anethole is approximately 24.90°C. This is calculated using the energy released in the combustion and the calorimeter's heat capacity.

Explanation:

The change in temperature of the calorimeter can be calculated using the relationship between the heat capacity of the calorimeter and the amount of heat released during combustion of the substance. Given the combustion of anethole releases 5541 kJ per mole, we first need to determine the amount of energy released during the combustion of 0.950 grams of anethole. Since the molecular weight of anethole (C10H12O) is approximately 148.2 g/mol, we can calculate q (the heat released) for the given mass, and then use this to determine the change in temperature (ΔT).

To calculate the energy released:

Then, using the calorimeter's heat capacity:

Hence, the change in temperature of the calorimeter is approximately 24.90°C.

When 3.60 g of aluminum reacts with hydrochloric acid at STP, approximately 4.48 liters of hydrogen gas is produced. This is calculated using stoichiometry and the conditions of STP, which state that one mole of any gas occupies 22.4 liters.

To calculate the volume of hydrogen gas produced when 3.60 g of Al reacts with hydrochloric acid, stoichiometry and the concept of Standard Temperature and Pressure (STP) can be used. Firstly, we need the molar mass of Al, which is approximately 26.98 g/mol. The number of moles of Al in 3.60 g can be calculated by dividing the mass by the molar mass. This gives us approximately 0.133 mol of Al. From the balanced chemical equation, we know that every 2 moles of Al produces 3 moles of H2, so 0.133 mol of Al would produce approximately 0.200 mol of H2.

As per the conditions of STP (Standard Temperature and Pressure), one mole of any gas occupies a volume of 22.4 liters. Therefore, 0.200 mol of H2 would occupy a volume of 0.200 * 22.4 L, which approximates to 4.48 L. So, when 3.60 g of aluminum reacts with hydrochloric acid under the conditions of STP, roughly 4.48 liters of hydrogen gas would be produced.

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Answer:

CaCl2

The charge can be +3 or +2

Explanation:

It takes two atoms of chloride and 1 atom of calcium to make this compound

Answer: chemical formula is CaCl2.

CaCl2------> Ca^2+ + Cl^-1

Explanation:

+2 for calcium ion and -1 for the chlorine ion.

For K2Cr2O7

The oxidation state of chromium=

(+1×2) + 2x + (-2×7) = 0

+2+2x-14= 0

2x= 12

x= 12/2

x=+6.

Therefore, the oxidation number of Chromium, Cr in K2CrO7 is +6

Answer:

0.52g

Explanation:

To calculate the mass of acetylene collected, we can calculate the number of moles of acetylene collected and multiply this by the molar mass of acetylene.

To calculate the number of moles of acetylene collected, we can use the ideal gas equation I.e PV = nRT

Rearranging the equation, n =PV/RT

We now identify each of the terms below before substituting and calculating.

n = number of moles, which we are calculating.

R = molar gas constant = 62.64 L.Torr. K^-1. mol^-1

V = volume = 459ml : 1000ml ÷ 1L, hence , 459ml = 459/1000 = 0.459L

T = temperature = 23 degrees Celsius = 273 + 23 = 296K

P = pressure. But since the gas was collected over water, we subtract the vapour pressure of water from the total pressure = 760 - 21 = 739torr

We substitute these values into the equation to yield the following:

n = (739 × 0.459) ÷ ( 62.64 × 300)

n = apprx 0.02 moles

To calculate the mass of acetylene collected, we need the molar mass of acetylene. The molecular formula of acetylene = C2H2, atomic mass of carbon = 12 and atomic mass of hydrogen = 1, thus , the molar mass = 2(12) + 2(1) = 26g/mol

Thus the mass of acetylene collected = 0.02 mole × 26g/mol = 0.52g

Final answer:

Enoyl-CoA isomerase bypasses a step that reduces Q, resulting in higher ATP yield. Even-chain saturated fatty acids are oxidized to acetyl-CoA in beta oxidation. Complete catabolism of a 15-carbon fatty acid requires some citric acid cycle enzymes.

Explanation:

Statement b is true. Enoyl-CoA isomerase, an enzyme in fatty acid metabolism, bypasses a step that reduces Q, resulting in higher ATP yield.

Statement c is true. Even-chain saturated fatty acids are oxidized to acetyl-CoA in the beta oxidation pathway.

Statement d is true. Complete catabolism of the three-carbon remnant of a 15-carbon fatty acid requires some citric acid cycle enzymes.

Explanation:

The bond order is defined as number of electron pairs present in a bond of the two atoms.

The formula of bond order is given by:

= [tex]\frac{1}{2}\times (\text{Number of bonding electrons}-\text{Number of anti-bonding electrons})[/tex]

1)  [tex](\sigma 1 s )^2 ( \sigma 1 s*)^2 (\sigma 2s )^2 ( \sigma 2 s*)^2 ( \sigma 2 p )^2 ( \pi2 p )^4 (\pi 2 p *)^2 [/tex]

Number of bonding electrons = 10

Number of anti-bonding electrons = 6

The bond order : [tex]\frac{1}{2}\times (10-6)=2[/tex]

2) [tex]( \sigma 1 s )^2 ( \sigma 1 s * )^2 ( \sigma 2 s )^2[/tex]

Number of bonding electrons = 4

Number of anti-bonding electrons = 2

The bond order : [tex]\frac{1}{2}\times (4-2)=1[/tex]

The bond order can be determined from the molecular electron configurations by counting the number of bonding and antibonding electrons and calculating the bond order as (number of bonding electrons - number of antibonding electrons)/2.

The bond order can be determined from the molecular electron configurations. In this case, the electron configuration given is ( σ 1 s ) 2 ( σ 1 s * ) 2 ( σ 2 s ) 2 ( σ 2 s * ) 2 ( σ 2 p ) 2 ( π 2 p ) 4 ( π 2 p * ) 2. We need to count the number of bonding and antibonding electrons to calculate the bond order. The number of bonding electrons is the sum of the electrons in all the bonding molecular orbitals. In contrast, the number of antibonding electrons is the sum of the electrons in all the antibonding molecular orbitals. The bond order is then calculated as (number of bonding electrons - number of antibonding electrons)/2. In this case, the bond order is (2+2+2+4-2)/2 = 4/2 = 2, indicating a double bond.

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Answer:

For a: The mass percent of NaBr is 7.03 %

For b: The mass percent of KCl is 16.94 %

For c: The mass percent of toluene is 13.43 %

Explanation:

To calculate the mass percentage of solute in solution, we use the equation:

[tex]\text{Mass percent of solute}=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times 100[/tex]         .......(1)

We are given:

Mass of NaBr (Solute) = 5.50 g

Mass of solution = 78.2 g

Putting values in equation 1, we get:

[tex]\text{Mass percent of NaBr}=\frac{5.50g}{78.2g}\times 100\\\\\text{Mass percent of NaBr}=7.03\%[/tex]

Hence, the mass percent of NaBr is 7.03 %

We are given:

Mass of KCl (Solute) = 31.0 g

Mass of water (solvent) = 152 g

Mass of solution = (31.0 + 152) g = 183 g

Putting values in equation 1, we get:

[tex]\text{Mass percent of KCl}=\frac{31.0g}{183g}\times 100\\\\\text{Mass percent of KCl}=16.94\%[/tex]

Hence, the mass percent of KCl is 16.94 %

We are given:

Mass of toluene (Solute) = 4.5 g

Mass of benzene (solvent) = 29 g

Mass of solution = (4.5 + 29) g = 33.5 g

Putting values in equation 1, we get:

[tex]\text{Mass percent of toluene}=\frac{4.5g}{33.5g}\times 100\\\\\text{Mass percent of toluene}=13.43\%[/tex]

Hence, the mass percent of toluene is 13.43 %

To calculate the percent by mass of the solute in each aqueous solution, divide the mass of the solute by the mass of the solution and multiply by 100%

To calculate the percent by mass of the solute in each aqueous solution, you'll need to use the formula:

Percent by mass = (mass of solute/mass of solution) x 100%

For example, in solution (a) with 5.50 g of NaBr in 78.2 g of solution, the mass of the solute is 5.50 g and the mass of the solution is 78.2 g. Plugging these values into the formula gives:

Percent by mass = (5.50 g / 78.2 g) x 100% = 7.03%

Similarly, you can calculate the percent by mass for solutions (b) and (c) using the same formula.

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Answer:

B > D > C > A

Explanation:

For the first law of the thermodynamics, the total energy variation in a process is:

ΔU = Q - W

Where Q is the heat, and W the work. If the system loses heat, Q < 0, if it absorbs heat, Q>0. If work is done in the system (volume decreases), W < 0, if the system does the work (volume increases), W > 0.

A. If the surroundings get colder, the system is absorbing heat, so Q>0, and the system decreases in volume so W < 0 :

ΔU = +Q - (-W) = +Q + W (absorbs a higher energy)

B. If the surroundings ger hotter, the system is losing heat, so Q<0, and the system expands, so W>0:

ΔU = -Q -W (loses higher energy)

C. Surroundings get hotter, Q<0, and the system decreases in volume, W<0

ΔU = - Q + W = 0 (magnitude of heat and work is similar)

D. Surroundings get hotter, Q<0, and the system is not changing in volume, W = 0.

ΔU = -Q (loses energy)

For the most released (more negative) for the most absorbed (most positive):

B > D > C > A

Final answer:

Reaction B is the most exothermic as it releases energy and the surroundings get hotter. Reaction D is less exothermic as the surroundings get warmer without volume change. Reaction A is most endothermic, absorbing energy, indicated by cooler surroundings.

Explanation:

Ranking the reactions from most energy released to most energy absorbed:

In summary, the reactions involving the surroundings getting warmer are generally exothermic, while those involving the surroundings getting colder are endothermic. The volume change provides additional clues about energy changes; expansion suggests work is done by the system (releasing energy), while a decrease in volume suggests work is done on the system (absorbing energy).

Answer:

0.121 moles of aluminum metal are required to produce 4.04 L of hydrogen gas at 1.11 atm and 27 °C by reaction with HCl

Explanation:

This is the reaction:

2 Al(s) + 6 HCl(aq) → 2 AlCl₃ (aq) + 3 H₂(g)

To make 3 moles of H₂, we need 2 moles of Al.

By conditions given, we will find out how many moles of H₂ do we have.

Let's use the Ideal Gas Law

P. V = n . R . T

1.11 atm . 4.04L = n . 0.082 L.atm/mol.K . 300K

(1.11 atm . 4.04L) / (0.082 mol.K/L.atm . 300K) = n

0.182 mol = n

So the rule of three will be:

If 3 moles of H₂ came from 2 moles of Al

0.182 moles of H₂ will come from x

(0.182 .2) / 3 = 0.121 moles

Answer:

V H2O = 170.270 mL

Explanation:

⇒ Q = mCΔT

∴ m: mass (g)

∴ C: specific heat

assuming:

⇒ Q coffe = (mcoffe)(C coffe)(60 - 95)

∴ m coffe = (180mL)(1.00 g/mL) = 180 g coffe

⇒ Q  = (180g)(4.186 J/°C.g)(-35°C) = - 26371.8 J

⇒ Q H2O = 26371.8 J = (m)(4.186 J/°C.g)(60 - 23)

⇒ (26371.8 J)/(154.882 J/g) = m H2O

⇒ m H2O = 170.270 g

⇒ V H2O = (170.270 g)(mL/1.00g) = 170.270 mL

Answer:

a, b and d are correct.

Explanation:

There are two types of attractive forces in covalent compounds:

Because intermolecular forces are usually quite weak compared with the forces holding atoms together within a molecule, molecules of a covalent compound are not held together tightly. Consequently, covalent compounds are usually gases, liquids, or low-melting solids.

Most covalent compounds aqueous solutions generally do not conduct electricity, because the compounds are nonelectrolytes.

Answer:

q= 110.5 ke

Explanation:

Dipole moment is the product of the separation of the ends of a dipole and the magnitude of the charges.

μ = q * d

μ= Dipole moment (1.93 D)

q= partial charge on each pole

d= separation between the poles(109 pm).

e= electronic charge ( 1.60217662 × 10⁻¹⁹ coulombs)

So,

q= [tex]\frac{1.93}{109 * 10^{-12} }[/tex] coulombs

q = [tex]\frac{1.93}{109 * 10^{-12} *  1.60217662 * 10^{-19} }[/tex] e

q = 1.105 * 10⁵ e

q= 110.5 ke

Answer:

The process is called Nitrogen fixation

Explanation:

The nitrogen fixation is a process carried out by some prokaryotic microorganisms (bacteria), specifically those have the presence of the nitrogenase enzyme. The bacteria absorb the atmospheric nitrogen (N2) from the roots of plants, and the nitrogenase enzyme, with the help of two proteins that act as electron donors and acceptors (nitrogenase complex) reduce the nitrogen to ammonia (NH3), then the ammonia is ionized to NH4+ (ammonium). Followed by that, the ammonia is oxidated to nitrates and nitrites, which are finally absorbed again by plants.

Answer:

There is 117.4 kJ of heat absorbed

Explanation:

Step 1: Data given

Number of moles CS2 = 1 mol

Temperature = 25° = 273 +25 = 298 Kelvin

Heat absorbed = 89.7 kJ

It takes 27.7 kJ to vaporize 1 mol of the liquid

Step 2: Calculate the heat that is absorbed

C(s) + 2S(s) → CS2(l)    ΔH = 89.7 kJ  (positive since heat is absorbed)

CS2(l) → CS2(g)           ΔH = 27.7 kJ  (positive since heat is absorbed)

We should balance the equations, before summing, but since they are already balanced, we don't have to change anything.

C(s) + 2S(s)---> CS2 (g)

ΔH = 89.7 + 27.7 = 117.4 kJ

There is 117.4 kJ of heat absorbed

Answer:

 [tex]M_2  = 1.094 M[/tex]

Explanation:

Given data:

V1 = 25.0 ml

M2 = 0.00383 M

V2 = 1000 ml

we knwo that [tex]M_1 V_1 = M_2 V_2[/tex]

    ∴ [tex]M_1 = \frac{M_2 V_ 2}{V_1}[/tex]

              [tex] = \frac{0.00383 M \times 1000}{25.0}[/tex]

               = 0.1532 M

0.1532 M is concentration in 25 ml but taken from 125 ml solution.

  ∴ The concentration in 125.0 ml solution is = 0.1532 M

M1 = 0.1532 M

V1 = 125.0ml and          V2 = 17.5.0ml

[tex]M_2 = \frac{M_1 V_1}{V_2}[/tex]

     [tex] = \frac{0.1532 M \times 125.0}{17.5}[/tex]

 [tex]M_2  = 1.094 M[/tex]

Answer:

Green

Explanation:

In the visible spectrum, which ranges from around 400-700 nm wavelength, the lower wavelength corresponds to the violet side of rainbow spectrum and, high wavelength corresponds to red side. As our solution absorbs highly at around 440 and 600 nm, it means that violet side and red side of the spectrum should be absorbed and would not be visible. the lowest absorbance at around 520 nm corresponds to green color, and therefore, it should be the colour visible from the solution

The solution would appear yellow-green in color due to the maximum and minimum absorbances observed in the visible spectrum.

The solution would appear yellow-green in color. The visible spectrum ranges from approximately 400 nm (violet) to 750 nm (red) with different colors corresponding to specific wavelengths. In this case, the maximum absorbances around 440 nm and 600 nm, and the minimum absorbance between 510 and 540 nm would indicate that the solution primarily absorbs light in the blue and red regions, resulting in the complementary color of yellow-green being observed.

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Answer:

Option b

Explanation:

The difference in the boiling points of ICl and Br2 is mainly due to the dipole-dipole interactions present between iodine and chlorine in the ICl molecule because as there is difference in electronegativity between iodine and chlorine these type of forces arise

As the dipole-dipole interactions are stronger, the stronger will be the boiling point of that compound because the forces between the molecules increases and as a result the boiling point of the compound increases

In case of Br2 as both are bromine atoms there will be no difference in electronegativity and therefore these type of interactions are not present

Molecular mass can also be a explanation for difference in normal boiling points because more molecular mass means more will be the vander waals forces but as dipole interactions are stronger than vander waals forces the major factor will be due to dipole interactions

The principal source of difference in the normal boiling points of ICI and Br2 is that ICI has stronger dipole-dipole interactions. Although both have similar London dispersion forces due to similar molecular masses, ICI being a polar molecule exhibits stronger dipole-dipole attractions, requiring more energy to overcome and hence has a higher boiling point.

The principal source of difference in the normal boiling points of ICI (97°C; molecular mass 162 amu) and Br2(59°C; molecular mass 160 amu) is that ICI has stronger dipole-dipole interactions than Br2. Both ICI and Br2 have similar masses and therefore experience similar London dispersion forces. However, compared to Br2 which is nonpolar, ICI is a polar molecule and thus also exhibits dipole-dipole attractions. These dipole-dipole attractions in ICI are stronger and require more energy to overcome, resulting in a higher boiling point for ICI.

Larger and heavier atoms and molecules like ICI exhibit stronger dispersion forces, leading to higher melting and boiling points. However, in the case of ICI and Br2, the effect of polar dipole-dipole attraction in ICI is more significant. This is apparent when we compare substances with similar molecular masses - the substance with the polar molecules has a higher boiling point, due to the stronger dipole-dipole attractions.

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Answer: 77.4 mL

Explanation:

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is:

[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]

where,

[tex]P_1[/tex] = initial pressure of dry gas = (760 - 17.5) mmHg= 742.5 mm Hg

[tex]P_2[/tex] = final pressure of dry gas at STP =  760 mm Hg

[tex]V_1[/tex] = initial volume of dry gas = 85.0 mL

[tex]V_2[/tex] = final volume of dry gas at STP = ?

[tex]T_1[/tex] = initial temperature of dry gas = [tex]20^oC=273+20=293K[/tex]

[tex]T_2[/tex] = final temperature of dry gas at STP = [tex]0^oC=273+0=273K[/tex]

Now put all the given values in the above equation, we get the final volume of wet gas at STP

[tex]\frac{742.5mmHg\times 85.0ml}{293K}=\frac{760mmHg\times V_2}{273K}[/tex]

[tex]V_2=77.4mL[/tex]

Volume of dry gas at STP is 77.4 mL.

Answer:

Limescale formed on kettle walls

Explanation:

A chemical reaction is one which is associated with a chemical change. While the other two examples are mere change in physical state, the formation of limescale on kettle is a chemical change. It is called the furring of kettles.

These limescales are formed when Calcium bicarbonate decomposes into calcium carbonate. It is this calcium carbonate that causes the furring of kettles.

It is one of the consequence of using temporary hard water. Temporarily hard water contains soluble magnesium bicarbonate and calcium bicarbonate. Now the heating of this water causes the decomposition of the calcium bicarbonate into calcium carbonate which forms these scales on the body of the kettle.

Calcium bicarbonate decomposes into calcium carbonate according to the following equation;

CaH(CO3)2 (aq)  --------->  CaCO3 (s)  + H2O (l)  + CO2 (g)

Answer:

The answer to your question is 21.45 g of KBr

Explanation:

Chemical reaction

                               2K + Br₂   ⇒   2KBr

                                       14.4            ?

Process

1.- Calculate the molecular mass of bromine and potassium bromide

Bromine = 2 x 79.9 = 159.8g

Potassium bromide = 2(79.9 + 39.1) = 238 g

2.- Solve it using proportions

              159.8 g of Bromine ------------ 238 g of potassium bromide                    

                14.4 g of Bromine  ------------  x

                        x = (14.4 x 238) / 159.8

                        x = 3427.2 / 159.8

                        x = 21.45g of KBr

Answer:

[tex]aam=\frac{\Sigma m_{i} \times ab_{i} }{100}[/tex]

Explanation:

When an atom has 2 or more isotopes, the average atomic mass (aam) depends on the mass of each isotope (mi) and the percentual abundance in nature of each isotope (abi). The average atomic mass can be calculated using the following expression:

[tex]aam=\frac{\Sigma m_{i} \times ab_{i} }{100}[/tex]

Answer:

Density is: 1.05 g/ml

Mole fraction solute: 0.015

Mole fraction solvent:  0.095

Molarity: 0.80 M

Molality: 0.82 m

Explanation:

A typical excersise of solution.

It is more confortable to make a table for this.

                |   masss  |  volume  |  mol

solute       |                |                |          

solvent     |                |                |  

solution    |                |                |

Let's complete, what we have.

                 |   masss  |  volume  |  mol

solute       |  10.8g     |                |          

solvent     |                |  133 mL   |  

solution    |                |  137 mL    |

We can first, know how many moles are 10.8 g

Molar Mass H3PO4 = 97.99 g/mol

Mass / Molar mass = mol

10.8 g / 97.99 g/m = 0.110 mol

Density of water is 1 g/ml (it is a very knowly value)

From this data, we can know water mass, solvent.

Density = mass / volume

1 g/ml = mass / 133 mL

Mass = 133 g

We can also have the moles, by the molar mass of water 18 g/m

133 g / 18 g/m = 7.39 mol

                 |   masss  |  volume  |  mol

solute       |   10.8g     |                |   0.110 mol      

solvent     |   133g      |  133 mL   |  7.39 mol

solution    |   143.8g   |  137 mL   | 7.50 mol

Mass of solution will be solute mass + solvent mass

Moles of solution will be solute moles + solvent moles

Now we can calculate everything.

Molarity means mol of solute in 1 L of solution. (mol/L)

We have to convert 137 mL in L (/1000)

0.137L so → 0.110 m / 0.137L = 0.80 M

Molality means mol of solute in 1kg of solvent.

We have to convert 133g in kg (/1000)

0.133 kg so → 0.110 m/0.133 kg = 0.82 m

Density is mass / volume

Solution density will be solution mass / solution volume

143.8 g/137 mL = 1.05 g/m

Molar fraction is : solute moles / total moles  or  solvent moles/total moles.

You can also (x 100%) to have a percent of them.

Remember sum of molar fraction = 1

Molar fraction of solute = 0.110 mol / 7.50mol = 0.015

Molar fraction of solvent = 7.39 mol / 7.50 mol = 0.985