: 1. Categorize each statement as true or false. Buffers are effective at resisting pH changes when large amounts of acid or base are added to a solution :: Chemical buffers are important to industrial production and to living systems. :: Chemical buffers have specific ranges and capacities. The buffer capacity is the pH range that is maintained when acids and bases are added to a solution True False 1 1

Answer:

2 kg

Explanation:

the half life of cesium is approx 30 years

  60 years is 2 half lives

       8 kg * 1/2 * 1/2 = 2 kg  

A. Carbon-14 can be used to date remains as far back as 60,000 years.

Carbon dating is a method for determining the age of an object containing organic material by using the properties of radioactive isotope of carbon.

Carbon-14 dating can be used to estimate the age of carbon-bearing materials up to about 58,000 to 62,000 years old.

Thus, Carbon-14 can be used to date remains as far back as 60,000 years.

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Answer:

1.8 x 10²⁴ atoms Ag

Explanation:

You can find the amount of silver (Ag) atoms by multiplying the moles by Avogadro's number. It is important to arrange the conversion in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 2 sig figs to match the sig figs of the given value.

Avogadro's Number:

6.022 x 10²³ atoms = 1 mole

3.0 moles Ag           6.022 x 10²³ atoms
----------------------  x  --------------------------------  = 1.8 x 10²⁴ atoms Ag
                                           1 mole

Answer:

C. It is hard to recreate the extremely high temperatures and pressures found inside stars.

Explanation:

Nuclear fusion occurs when atomic nuclei are forcefully combined to create a new atomic nuclei or subatomic particles. In nature, this process takes place in our Sun and other stars. Within stars, extremely high temperatures and pressures are achieved and cause nuclear fusion to occur. Humans have not yet been successful in recreating the environment necessary to mimic this process.

Taking into account the definition of molarity,  the molarity of a solution that contains 30 moles naoh in 0.80 liters of solution is 37.5 [tex]\frac{moles}{liters}[/tex].

Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.

The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:

[tex]Molarity=\frac{number of moles}{volume}[/tex]

Molarity is expressed in units [tex]\frac{moles}{liters}[/tex].

In this case, you have:

Replacing in the definition of molarity:

[tex]Molarity=\frac{30 moles }{0.80 L}[/tex]

Solving:

Molarity= 37.5 [tex]\frac{moles}{liters}[/tex]

Finally, the molarity of a solution that contains 30 moles naoh in 0.80 liters of solution is 37.5 [tex]\frac{moles}{liters}[/tex].

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Answer:

Ca = 1s²2s²2p⁶3s²3p⁶4s²

Explanation:

Calcium is located in the second column and the 4th row of the periodic table. Thus, there are 2 valence electrons and the highest quantum number is 4. This is represented by 4s². However, all of the previous orbitals and electrons must be listed beforehand, making the entire electron configuration: 1s²2s²2p⁶3s²3p⁶4s².

The equation for ideal gas law is written as PV = nRT.

Ideal gas law states that, the volume of a given amount of gas is directly proportional to the number on moles of gas, directly proportional to the temperature and inversely proportional to the pressure.

PV = nRT

where;

Thus, the equation for ideal gas law is written as PV = nRT.

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The volume of the 0.1 M buffer from Part A needed to make 100 mL of a 0.01 M buffer is 10mL.

The volume of a substance can be calculated using the following formula;

C1V1 = C2V2

Where;

0.1 × V1 = 100 × 0.01

0.1V1 = 1

V1 = 1/0.1

V1 = 10mL

Therefore, the volume of the 0.1 M buffer from Part A needed to make 100 mL of a 0.01 M buffer is 10mL.

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The new pressure changed relative to the original by a factor of 8/3.

Using the ideal gas equation;

PV = nRT

P = pressure

V = volume

n = number of moles

R = gas constant

T = temperature

P1 = nRT/V

P2 = 4n * R * 2T/3V

Hence;

P2/P1 = 4n * R * 2T/3V ÷  nRT/V

P2/P1 = 4n * R * 2T/3V * V/nRT

P2/P1 =4 * 2/3

= 8/3

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1.  The mass of Fe2O3 required will be 51.29 grams

2. The mass of Cu that will be formed is 36 kg

1) The equation of the reaction goes thus: [tex]2Fe_2O_3 + 3Pt --- > 3PtO_2 + 4Fe[/tex]

Mole ratio of Fe to Fe2O3 = 2:1

Mole of 35.9 g Fe = 35.9/56 = 0.6411 mol

Equivalent mole of Fe2O3 = 0.6411/2 = 0.3205 mol

Mass of 0.3205 mol Fe2O3 = 0.3205 x 160 = 51.29 grams

2) [tex]2CuO --- > 2Cu + O_2[/tex]

Mole ratio of CuO to Cu = 1:1

Mole of 45 kg CuO = 45000/80 = 562.5 mol

Equivalent mole of Cy = 562.5 mol

Mass of 562.5 mol of Cu = 562.5 x 64 = 36,000 grams or 36 kg

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The answer is 1) mixing of two gases by diffusion.

Once 2 gases are mixed by diffusion, they cannot be obtained from the mixture of gases. Hence, it is considered to be an irreversible process.

Answer:

1) a) 1.81  × 10²³ molecules (b) 1.93  × 10²³ molecules (c) 0.66× 10²³ molecules

2) a) 0.45× 10²³ions  (b) 0.84× 10²³ions (c) 3.6 × 10²³ions

Explanation:

1) Number of molecules:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

a) 16g of H₂CO₃

Number of moles = mass/ molar mass

Number of moles = 16 g/ 62.03 g/mol

Number of moles = 0.3 mol

1 mol = 6.022 × 10²³ molecules

0.3 mol ×  6.022 × 10²³ molecules /1 mol

1.81  × 10²³ molecules

b) 20g of HNO₃

Number of moles = mass/ molar mass

Number of moles = 20 g/ 63.01 g/mol

Number of moles = 0.32 mol

1 mol = 6.022 × 10²³ molecules

0.32 mol ×  6.022 × 10²³ molecules /1 mol

1.93  × 10²³ molecules

c) 30g of C₆H₁₂O₆

Number of moles = mass/ molar mass

Number of moles = 20 g/ 180.156 g/mol

Number of moles = 0.11 mol

1 mol = 6.022 × 10²³ molecules

0.11 mol ×  6.022 × 10²³ molecules /1 mol

0.66× 10²³ molecules

2. Calculate the number of ions in the following compounds:

a) 10g of AlCl₃

Number of moles = mass/ molar mass

Number of moles = 10g/ 133.34 g/mol

Number of moles = 0.075 mol

1 mol = 6.022 × 10²³ ions

0.075 mol ×  6.022 × 10²³ ions/1 mol

0.45× 10²³ions

b) 30g of BaCl₂

Number of moles = mass/ molar mass

Number of moles = 30g/ 208.23 g/mol

Number of moles = 0.14 mol

1 mol = 6.022 × 10²³ ions

0.14 mol ×  6.022 × 10²³ ions/1 mol

0.84× 10²³ions

c) 58 g of H2SO4

Number of moles = mass/ molar mass

Number of moles = 58g/ 98.079 g/mol

Number of moles = 0.59 mol

1 mol = 6.022 × 10²³ ions

0.59 mol ×  6.022 × 10²³ ions/1 mol

3.6 × 10²³ions

Explanation:

The government gave the people more freedom to criticize the government which led to nationalist movements

In the late 1980s, the economic and social situation in the Soviet Union was tense. The socialist economy was on the verge of collapse, the war in Afghanistan was an assured defeat, and the quality of life for Soviet citizens was appalling.

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To calculate the molar mass of substance, divide the number of moles by the given mass of substance.

The quantity of a substance is known as a mole. You can measure it in terms of grams, liters, atoms, molecules, or particles.

Use the substance's molar mass to convert between grams and moles. Divide the given mass by the number of moles to convert from moles to molar mass.

Using the formula, Number of moles = Given mass/ molar mass

The molar mass of a substance can be calculated as-

Molar mass = Given mass/number of moles

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Amount of nitrogen produced = 1.624 g

To calculate the moles, we use the equation:    

4NH3(g) + 3 O2 (g) ---> 2 N2 (g) + 6 H2O (g)                           ....(1)

For ammonia:

Putting values in above equation, we get:

Moles of ammonia = 7.00 x 1022 / 6.023 * 10 ^23 = 0.116 mol

Moles of oxygen = 6.00 x 1022 / 6.023 * 10 ^23 = 0.099 mol

For the reaction:

4NH3(g) + 3 O2 (g) ---> 2 N2 (g) + 6 H2O (g)

By Stoichiometry of the reaction,

4 moles of ammonia combine with 3 moles of Oxygen

Thus 0.116 moles of ammonia will combine with= 3/4 * 0.116 = 0.087 of oxygen

Thus ammonia is the limiting reagent as it limits the formation of product.

4 moles of ammonia produces 2 moles of nitrogen

0.132 moles of ammonia will produce=2/4 * 0.116 = 0.058 of nitrogen

Molar mass of nitrogen =  28 g/mol

Amount of nitrogen produced=

No of moles * molar mass = 0.058 * 282 = 1.624 g

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Answer:

C) ZnCl2(s) + H2(g)

Explanation:

On reaction between Zn and HCl, Zn is more reactive than Hydrogen thus displacing it from HCl making a bond with two atoms of chlorine and releases hydrogen gas.

The equation of reaction

Zn(s) + HCl(aq) => ZnCl2(s) + H2(g).

Therefore, the required products are ZnCl2(aq) and H2(g).

The amount of space that matter occupies is called its volume. Solids, liquids, and gases all have volume.

Find the expected yield of lead:

The expected yield of lead if 50.0 kg of lead oxide is heated with 50.0 kg of carbon is 46 kg

Calculation:

First and foremost, we must correctly write the equation of reaction in order to answer this issue. This is what it is:

PbO(s) + C(s) → Pb(l) + CO (g)

We continue from here. The limiting reactant should be found, however finding out how many moles of each reactant are present is the only way to do so.

The number of moles is calculated using the formula: the mass of each reactant divided by the molar mass of each reactant.

Mass of PbO is 50kg = 50000g

Molar mass of PBO = 223.20g/mol

The number of moles is thus 50000/223.2 = 224 moles

For carbon, mass is also 50kg = 50000g

Molar mass is 12g/mol

Number of moles of carbon = 50000/12 = 4166.6 moles

We can observe from the number of moles that there are more moles of carbon than PbO. This indicates that the limiting reagent is PbO.

So, in order to determine percentage yield, we employ it.

Since we have a mole ratio of 1 to 1, the number of moles of lead created is equal to the number of moles of lead oxide, which is 224.

The molar mass of lead = 207.20 g/mol

The mass of lead formed = moles of lead x molar mass of lead

The mass of lead formed = 207.20 x 224 =  46,412.8 g = 46 kg

Hence, the expected yield is 46 kg.

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Water cycle simply refers to the continuous movement or flow of water from the atmosphere to the earth and back to the atmosphere

These are the basic stages through which water passes. These stages are:

So therefore, water cycle simply refers to the continuous movement or flow of water from the atmosphere to the earth and back to the atmosphere

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Answer:

A.) combustion

Explanation:

Combustion reactions are a specific type of redox reaction which always have the same general structure: CₓHᵧ + O₂ ---> H₂O + CO₂ + heat/light

Decomposition reactions are reactions which involve a molecule breaking down into smaller compounds/elements. They have the general structure: AB ---> A + B

Double replacement reactions are reactions in which the cation of one compound is swapped with the cation of another compound. They have the general structure: AB + CD ---> AD + CB

A detailed article on formation of poly [(fluorophenyl) acetylene]s prepared with metathesis and insertion catalysts has been given below.

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Answer:

d

Explanation:

22.4 L is the same as 1 mol.

Diatomic nitrogen has a formula mass of 28.01 g/mol, so the answer is d.

The four items that change in the hazard communication standard for chemical labels and SDS

This is further explained below.

Generally, The Hazard Communication Standard (HCS) was developed to ensure that employees have the "right to know" about any possible dangers that may be related to the work that they do. The HCS is a preventative strategy that is meant to distribute information to employees and employers about the health dangers that are associated with the chemicals that they handle and the protection that is necessary.

In conclusion, Hazard communication labels and SDS product identifiers have undergone four changes as a result of the new standard. The term serves as a signal to the driver. There is a risk. Pictograms. Statement of caution.

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Answer:

3.2 g O₂

Explanation:

To find the mass of O₂, you need to (1) convert grams H₂O to moles H₂O (via molar mass), then (2) convert moles H₂O to moles O₂ (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles O₂ to grams O₂ (via molar mass). It is important to arrange the ratios/conversions in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 2 sig figs to reflect the sig figs of the given value (3.6 g).

Molar Mass (H₂O): 2(1.008 g/mol) + 15.998 g/mol

Molar Mass (H₂O): 18.014 g/mol

2 H₂O -----> 2 H₂ + 1 O₂

Molar Mass (O₂): 2(15.998 g/mol)

Molar Mass (O₂): 31.996 g/mol

3.6 g H₂O         1 mole               1 mole O₂           31.996 g
----------------  x  ---------------  x  ---------------------  x  ---------------  = 3.2 g O₂
                         18.014 g          2 moles H₂O          1 mole

Answer:

C₂H₄O₂

Explanation:

To find the molecular formula of the organic acid, you need to (1) determine the mass of each element (from the given percents), then (2) convert grams of each element to moles (via atomic masses), then (3) find the empirical formula, and then (4) find the molecular formula.

(Step 1)

39.9% C -----> 39.9 g C

6.7% H -----> 6.7 g H

53.4% O -----> 53.4 g O

(Step 2)

Atomic Mass (C): 12.011 g/mol

Atomic Mass (H): 1.008 g/mol

Atomic Mass (O): 15.988 g/mol

39.9 grams C             1 mole
----------------------  x  ----------------------  = 3.32 moles C
                                12.011 grams

6.7 grams H              1 mole
--------------------  x  ---------------------  =  6.65 moles H
                              1.008 grams

53.4 grams O              1 mole
----------------------  x  ----------------------  =  3.34 moles O
                                15.998 grams

(Step 3)

The empirical formula is made up of the lowest possible amount of each element in the molecule. These amounts can be found by dividing the molar value of each element by the smallest molar value. In this case, the smallest molar value is 3.32 moles C. The calculated values make up the subscripts in the empirical formula.

3.32 moles C / 3.32  =  1 mole C

6.65 moles H / 3.32  =  2 moles H

3.34 moles O / 3.32  =  1 mole O

Empirical Formula: CH₂O

(Step 4)

To find the molecular formula, you first need to determine the molar mass of the empirical formula. Once you have this value, you need to determine how much you need to scale the formula up by. In this case, the molar mass of the empirical formula is half of the molar mass of the molecular formula. Therefore, you need to multiply the amount of each element in the molecule by 2.

Molar Mass (CH₂O): 12.011 g/mol + 2(1.008 g/mol) + 15.998 g/mol

Molar Mass (CH₂O): 30.025 g/mol

30.025 g/mol x 2 = 60.05 g/mol

CH₂O x 2 = C₂H₄O₂

A photon has an energy of 2.88 × 10⁻¹⁸ J. The energy into eV is 17.97 eV.

The energy which is carried by a single photon is called Photon energy.

It is expressed as:

E = hf

where,

E = Photon energy

h = Planck's energy

f = Wave frequency

To convert J into eV

E(eV) = E(J) × 6.241509 × 10¹⁸

         = 2.88 × 10⁻¹⁸ × 6.241509 × 10¹⁸

         = 17.97 eV

Thus from the above conclusion we can say that A photon has an energy of 2.88 × 10⁻¹⁸ J. The energy into eV is 17.97 eV.

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Answer:

45.82 gm O2

Explanation:

From your balanced equation in the first part, you can see that 2 moles propane  need 7 moles O2

Find the number of moles of propane in 18 gm

   mole wt of propane = ~  12 * 3 + 8 *1 = 44 gm/mole

      18 gm /  44 gm/mole  =  9/22 gm/mole  propane

            we need 7/2 of this as O2 moles    7/2 * 9/22 = 1.432moles of O2

 O2   mole weight =~ 32

       1.432 moles * 32 gm/mole = 45.82 gm O2

H₂CO₃ will be produced faster  if carbonic anhydrase acts as a catalyst and the correct option is option B.

Carbonic anhydrase enzyme helps to maintain acid-base homeostasis, fluid balance and regulate pH. Based on its location, the enzyme role changes slightly.

The inter-conversion that occurs between water, carbon dioxide, and dissociated carbonic acid ions, is catalyzed by a group of enzymes that form by carbonic anhydrase, or carbonate dehydratase.

The active site for most carbonic anhydrase is supposed to be a zinc ion, and it is as a result classified as metalloenzymes.

Therefore, H₂CO₃ will be produced faster  if carbonic anhydrase acts as a catalyst and the correct option is option B.

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The amount of energy, in Joules, that the food contains will be 414.8 Joules

According to metrics, 1 kilocalorie = 4184 Joules.

100 Calories = 100/1000 = 0.1 kiloCalories.

0.1 kilocalories = 0.1 x 4184 = 414.8 Joules

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The option that has little bearing on whether profitable opportunity exists is option c) How many companies in the industry have expanded their plant capacity since Year 10 because it is not detailed enough.

Decision making is known to be a term that connote the method or act that is based on making the right and best decision among the numbers of alternative available.

Note that  It includes the act of classifying and knowing the best on the use of preference, belief, and others.

Therefore, the option that has little bearing on whether profitable opportunity exists is option c) How many companies in the industry have expanded their plant capacity since Year 10 because it is not detailed enough.

See full question below

Which one of the following has little bearing on whether profitable opportunity exists to build additional plant capacity in the upcoming decision round?

a) Whether data in the most recent FIR indicates that unsold inventories of branded footwear were so disturbingly high that many of these unsold pairs were cleared from company inventories at money-losing prices.

b) Whether the most recent year's FIR shows that ample production capacity already exists to supply the combined demand for branded footwear and private-label footwear three years from now.

c) How many companies in the industry have expanded their plant capacity since Year 10.

d) How potential global supply of footwear in the upcoming year compares with expected global demand

e) Whether the branded pairs available for sale in the most recent year (as reported in FIR)

exceeded global branded demand and, if so, by how much.

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