Which of the following aqueous solutions are good buffer systems?

(Select all that apply.)

a. 0.22 M acetic acid + 0.15 M potassium acetate
b. 0.27 M nitric acid + 0.16 M potassium nitrate
c. 0.29 M ammonium nitrate + 0.32 M ammonia
d. 0.20 M calcium hydroxide + 0.23 M calcium chloride
e. 0.31 M hydrofluoric acid + 0.22 M potassium fluoride

The balanced redox reaction in the chemical reaction is given below:

40H2S + 48H+ + 16MnO4¯ ---> 5S8 + 16Mn2+ + 64H2O

Balancing the redox reaction:

Solution:

1) Half-reactions:

H2S ---> S8

MnO4¯ ---> Mn2+

2) Balance:

8H2S ---> S8 + 16H+ + 16e¯

5e¯ + 8H+ + MnO4¯ ---> Mn2+ + 4H2O

3) Make the number of electrons equal (note that there are no common factors between 5 and 16 except 1):

40H2S ---> 5S8 + 80H+ + 80e¯ <--- factor of 5

80e¯ + 128H+ + 16MnO4¯ ---> 16Mn2+ + 64H2O <---

factor of 16

4) Thus, the final answer is given below;

40H2S + 48H+ + 16MnO4¯ ---> 5S8 + 16Mn2+ + 64H2O

Oxidation-reduction can simply be defined as a special type of chemical reaction in which the oxidation states of the substrate change.

So therefore, the balanced redox reaction in the chemical reaction is given below:

40H2S + 48H+ + 16MnO4¯ ---> 5S8 + 16Mn2+ + 64H2O

Complete question:

Balance the following redox reaction:

MnO4¯ + H2S ---> Mn2+ + S8

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Answer: 1

Explanation: Lithium has a single electron in the second principal energy level, and so we say that lithium has one valence electron.

1 is correct

for brainliest

Answer:

78.7

Explanation:

The number has 4 significant figures: 7,8 6 and 5.

To round off to 3 significant figures, the target digit is the third significant figure in the number.The determining digit is the fourth significant figure in the number; it is 5 hence the target digit will go up by 1 and any digits to the right of it will be rounded down to 0.

Answer:

[tex]\boxed{\sf no.\ of \ molecules = 7.13 \times 10^{22} \ molecules}[/tex]

Explanation:

Mass in g = m = 5.68 g

Molar mass = M = (16)3 = 48 g/mol

Avogadro's number = [tex]N_A[/tex] = 6.023 × 10²³

No. of molecules = ?

[tex]\displaystyle no.\ of \ molecules = \frac{m}{M} \times N_A[/tex]

Put the givens in the above formula

[tex]\displaystyle no. \ of \ molecules =\frac{5.68}{48} \times 6.023 \times 10^{23}\\\\no. \ of\ molecules = 0.12 \times 6.023 \times 10^{23}\\\\no. \ of \ molecules = 0.713\times 10^{23}\\\\no.\ of \ molecules = 7.13 \times 10^{22} \ molecules\\\\\rule[225]{225}{2}[/tex]

Answer:

Covalent bonds are intramolecular bonds whereas hydrogen bonds are intermolecular bonds.

hope this helps and good luck :)

The pH of a 0.0100 M sodium benzoate solution is determined as 8.09.

The pH of a solution is a measure of hydrogen (H+) ion concentration, which is, in turn, a measure of acidity of the solution.

pH is can also be determined from pOH of the solution as shown below;

pH = 14 - pOH

let the hydroxyl concentration, OH = x

x²/M = kb

x²/0.01 = 1.5 x 10⁻¹⁰

x² = 1.5 x 10⁻¹²

x = √(1.5 x 10⁻¹²)

x = 1.2247 x 10⁻⁶

pOH = - log(OH⁻)

pOH = -log( 1.2247 x 10⁻⁶)

pOH = 5.91

pH = 14 - 5.91

pH = 8.09

Thus, the pH of a 0.0100 M sodium benzoate solution is determined as 8.09.

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Answer:

d

Explanation:

d

Taking into account the definition of calorimetry, sensible heat and latent heat, the heat needed to melt 10.0 grams of ice at -10°C until it is water at 10°C is 3,969.5 J.

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

In this case, the amount of heat a body receives or transmits is determined by:

Q = c× m× ΔT

where:

Latent heat is defined as the energy required by a quantity of substance to change state.

When this change consists of changing from a solid to a liquid phase, it is called heat of fusion and when the change occurs from a liquid to a gaseous state, it is called heat of vaporization.

In this case, the heat Q that is necessary to provide for a mass m of a certain substance to change phase is equal to

Q = m×L

where L is called the latent heat of the substance and depends on the type of phase change.

First, you  have to get the ice from -10°C to 0 °C, which is the melting point.  Then you have to melt the ice into liquid water. Now, you have to get the water from 0°C to 10°C.

In this case, you know:

Replacing in the definition of sensible heat:

Q1= 2.108 [tex]\frac{J}{gK}[/tex]× 10 g× 10 K

Solving:

Q1= 210.8 J

In this case, you have to melt the ice into liquid water. Being the specific heat of melting of ice is 334 J/g, the heat needed to melt 10 grams of ice is calculated as:

Q2= 10 grams× 334 J/g

Solving:

Q2= 3,340 J

In this case, you know:

Replacing in the definition of sensible heat:

Q3= 4.187 [tex]\frac{J}{gK}[/tex]× 10 g× 10 K

Solving:

Q3= 418.7J

The total heat required is calculated as:  

Total heat required= Q1 + Q2 + Q3

Total heat required= 210.8 J + 3,340 J + 418.7 J

Total heat required= 3,969.5 J

In summary, the heat needed to melt 10.0 grams of ice at -10°C until it is water at 10°C is 3,969.5 J.

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Answer:

61 atm

Explanation:

You can calculate osmotic pressure using the following equation:

π = i MRT

In this equation,

-----> π = osmotic pressure (atm)

-----> i = van't Hoff's factor

-----> M = molarity (M)

-----> R = Ideal Gas Constant (0.08206 atm*L/mol*K)

-----> T = temperature (K)

The van't Hoff's factor is the amount of ions the substance dissociates into. Since sugar does not dissociate, this value is 1. After converting Celsius to Kelvin, you can plug the values into the equation and simplify.

i = 1                                 R = 0.08206 atm*L/mol*K

M = 2.5 M                      T = 25 °C + 273.15 = 298.15 K

π = i MRT

π = (1)(2.5 M)(0.08206 atm*L/mol*K)(298.15 K)

π = 61 atm

The oxidation number of chlorine in KClO3 is +5 (option A).

The oxidation number of an element is the hypothetical charge of an atom within a molecule.

The oxidation number of an element like chlorine in a compound like Pottasium chlorate can be calculated as follows:

The oxidation number of the elements in KClO3 is as follows:

1 + x - 2(3) = 0

x - 5 = 0

x = +5

Therefore, the oxidation number of chlorine in KClO3 is +5.

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This is an exercise in the general or combined gas law.

To start solving this exercise, we obtain the following data:

We use the following formula:

P₁V₁T₂ = P₂V₂T₁ ⇒ General formula

Where

We clear the formula for the initial volume:

[tex]\boldsymbol{\sf{V_{1}=\dfrac{P_{2}V_{2}T_{1}}{P_{1}T_{2}} } }[/tex]

We substitute our data into the formula to solve:

[tex]\boldsymbol{\sf{V_{1}=\dfrac{(3.69 \not{atm})(56.4 \ ml)(295.5 \not{k})}{(1.95 \not{atm})(284.9\not{k})} }}[/tex]

[tex]\boldsymbol{\sf{V_{1}=\dfrac{61498.278}{555.555} \ lm }}[/tex]

[tex]\boxed{\boldsymbol{\sf{V_{1}=110.697 \ lm }}}[/tex]

The helium-filled balloon has a volume of 110.697 ml.

Answer:

111  ml

Explanation:

Use the general rule for gases:

P1 V1 / T1    =   P2 V2 / T2      Looking for V1     T must be in Kelvin

re-arrange to :

V1 =   P2 V 2  * T1 / (T2 * P1)      <==== now sub in the values

V1 = 3.69 * 56.4 * (22.5 + 273.15) / [(11.9 + 273.15) * 1.95]

V1 = 110.6949 ml

    for correctness, the answer should only have THREE significant digits as all of the factors have three SD

V1 = 111 ml

Answer:

B

Explanation:

Planting trees sequesters CO2

  all of the other choices produce more CO2 in the atmosphere

When the crystals of potassium permanganate are preserved in water, the purple-coloured crystals of potassium permanganate break further into smaller particles that populate the distance between the molecules of water imparting a purple colour to the water. This is an example of diffusion.

Diffusion is the process of movement of solvent from higher concentration to lower concentration through a semipermeable membrane. So, we can form the decision that it cannot occur through a thick membrane from which small molecules cannot pass through.

Osmosis is the direction of solvent particles from a solution that is diluted to a more concentrated one. In contrast, diffusion is the movement of particles from a higher concentration region to a part of lower concentration.

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The product of the given reaction and the balanced form is as follows: Cu3(PO4)2 + 2Fe(OH)3 → 2FePO4 + 3Cu(OH)2 (option C).

A chemical reaction involves the formation of products from the combination of two or more reactants.

However, for the reaction to be balanced, the number of moles of each element on both sides of the equation must be equal.

According to this question, the following reaction is given: Cu3(PO4)2 + Fe(OH)3 → ?

The product of the given reaction and the balanced form is as follows: Cu3(PO4)2 + 2Fe(OH)3 → 2FePO4 + 3Cu(OH)2.

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(a) The edge length of the unit cell is 286 pm.

(b) The  the density of aluminum metal is 1.27 x 10⁻²³ g/cm³.

The edge length of the aluminum atom is calculated as follows;

a = 2r

where;

a = 2 x 143 pm = 286 pm

V = a³

V = (286 x 10⁻¹²)³

V = 2.34 x 10⁻²⁹ m³

ρ = ZM/VN

where;

ρ = (4 x 4.479 x 10⁻²³) / ( 2.34 x 10⁻²⁹ x 6.023 x 10²³)

ρ = 1.27 x 10⁻¹⁷ g/m³

ρ = 1.27 x 10⁻¹⁷ g/m³  x (1 m³ / 10⁶ cm³)

ρ = 1.27 x 10⁻²³ g/cm³

Thus, the edge length of the unit cell is 286 pm and the  the density of aluminum metal is 1.27 x 10⁻²³ g/cm³.

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If the mass of the sun is 2x, at least one planet will fall into the habitable zone. if I place a planet in orbits 84, 1, and 5, and all planets will orbit the sun successfully.

The size of the sun and motion of planets around it is illustrated below;

If the mass of the sun is 1x, at least one planet will fall into the habitable zone. if I place a planet in orbits 2, 6, and 75, and all planets will orbit the sun successfully.

If the mass of the sun is 2x, at least one planet will fall into the habitable zone. if I place a planet in orbits 84, 1, and 5, and all planets will orbit the sun successfully.

If the mass of the sun is 3x, at least one planet will fall into the habitable zone if I place a planet in orbits 672, and 7 and all planets will orbit the sun successfully.

Thus, If the mass of the sun is 2x, at least one planet will fall into the habitable zone. if I place a planet in orbits 84, 1, and 5, and all planets will orbit the sun successfully.

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Answer:

It's the button with the x, and a blank box above it.

Explanation:

Check the attachments, you'll see what it looks like. It will probably look different on your calculator, but the icon should be the same or similar.

Stoichiometry is used in formulating airbags that shows relationship between product and reactants.

The quick chemical decomposition of solid sodium azide (NaN3) that allows the air bag to inflate fast at any time when the car hit anything. The decomposition reaction is initiated in a car by a small ignition that occurs due to collision sensing mechanism. The nitrogen gas produced during the reaction inflates the air bag which protect the person in the car.

So we can conclude that Stoichiometry is used in formulating airbags that shows relationship between product and reactants.

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Stoichiometry is important in formulating airbags, producing contrails, or formulating rocket engines so as to ensure the required amount of products are formed.

Stoichiometry is the molar relationship between the reactants and products of a reaction.

It is the ratio in which moles of reactants of a reaction combine to form moles of products.

Stoichiometry is important in determining the amount of reactants required to produce a given amount of products.

For example, stoichiometry is important in formulating airbags, producing contrails, or formulating rocket engines in order to ensure the mass of reactants used is enough to produce the required products.

In conclusion, stoichiometry of  a reaction provides the knowledge about the amount of reactants required to form products.

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Taking into account the definition of pH and pOH, [H₃O⁺] will be 1×10⁻³ M.

pH is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance.

The pH is defined as the negative base 10 logarithm of the activity of hydrogen ions, that is, the concentration of hydrogen ions or H₃O⁺:

pH= - log [H⁺]= - log [H₃O⁺]

Similarly, pOH is a measure of hydroxyl ions in a solution and is expressed as the logarithm of the concentration of OH⁻ ions, with the sign changed:

pOH= - log [OH⁻]

The following relationship can be established between pH and pOH:

pOH + pH= 14

In this case, you know that [OH⁻]= 1×10⁻¹¹ M.

Replacing in the definition of pOH, it is calculated as:

pOH= - log (1×10⁻¹¹ M)

Solving;

pOH= 11

Replacing in the relationship established between pH and pOH, the pH can be calculated as:

pH + 11= 14

Solving:

pH= 14 - 11

pOH= 3

Replacing in the definition of pH the concentration of H₃O⁺ ions is obtained:

- log [H₃O⁺]= 3

Solving:

[H₃O⁺]= 10⁻³

[H₃O⁺]= 1×10⁻³ M

In summary, [H₃O⁺] will be 1×10⁻³ M.

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Answer:

liquids have more kinetic energy than solids

Explanation:

water and ice are good examples

hotter the faster

kinetic can mean speed

solids held together by strong intermolecular forces of attraction

very little or no kinetic energy between the particles

solids are rigid and have definite shape and volume

liquid particles are held by weaker Vander Waal forces.

particles collide with each other and gain kinetic energy.

liquids have more kinetic energy than in the solid phase.

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Answer:

SO2(g) + O2(g) SO3(g) (needs to be balanced. Balance it by placing a 1/2 in front of the 02.) This is a 5-sig-fig problem, so when you calculate your molar masses, you must use all of the sig figs available to you from the periodic table. That's how you can get this problem correct. Melissa Maribel likes to round the numbers from the periodic table, and usually that is ok. But for problems where you have many sig figs, your molar masses from the periodic table must have at least as many sig figs as your data. Therefore, for each oxygen atom, please use 15.9994 g/mol. For each sulfur atom, please use 32.066 g/mol. Thank you.

Answer:

7.1029 gms of O2

Explanation:

First balance the equation to get

2 SO2  + O2 ====>  2 SO3

Mole weight of sulfur dioxide gas

 S   +   2 O  ==   32.066 + 2 * 15.999   = 64.064 gm/mole  ( 5 signif digits)

     28.442 gm / 64.064 gm/mole = .44396 mole  of SO2 ( 5 sig digits)

From the balanced equation, you can see you need 1/2 as many moles of O2   as  SO2:

mole weight of O2  =   2 * 15.999 = 31.998 gm / mole   ( 5 sig digits)

   now you need    1/2  of  .44396 moles of this

              1/2  * .44396  * 31.998 = 7.1029  gm    ( 5 sig digits)

Answer:

C6H6O2

Explanation:

Total mass of empirical =55

Total mass of compound is 110. So you need to multiply each atims by 2

Answer:

D

Explanation:

Ideal gas law    PV = n RT     R = .082057      T   must be in Kelvin  

                                               n = moles

V = n RT / P

  = 1.5 (.082057) ( 27+ 273.15) / 2 = 18.5 liters

Answer: D. They are slippery.

Explanation:

         Only one of the following is a property of bases. This is option D, they are slippery. Bases usually feel slippery, which can also be described as "soapy." Many soaps, shampoos, detergents, etc contain bases.

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This exercise is related to the subject of Structured Thinking. See the definition of structured thinking below.

The process of developing a structured framework to address an unstructured situation is known as structured thinking.

Structured thinking is a strategy of problem-solving that entails breaking a huge problem into smaller ones in order to tackle the larger problem more quickly and effectively.

Categorizing things and identifying themes are two subjects under structured thinking.

To categorize anything requires:

Identifying themes entails:

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The condition that will increase the entropy in a reaction is heating up the reaction (option B).

Entropy in chemistry is the measure or degree of the disorder or randomness present in a chemical system.

In a chemical reaction, reacting substances called reactants collide with one another to form products.

However, the degree at which the reactants collide with one another is referred to as the entropy of the reaction.

Therefore, the condition that will increase the entropy in a reaction is heating up the reaction i.e. increase in temperature.

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Answer:

A.) 2,4,5-trimethylhexan-2-ol

B.) 6-bromo-3-ethylhexan-2-one

C.) 3-isoproyl-4-propyloctan-1-al

Explanation:

A.) Since there is an alcohol (-OH) group in the molecule, the name should have the ending -ol. Since the alcohol is on the 2nd carbon, there should be a 2 in front of the -ol. The longest carbon chain contains 6 single-bonded carbons, making this a hexane. There are 3 methyl (-CH₃) groups on the 2nd, 4th, and 5th carbons.

Therefore, the IUPAC name is: 2,4,5-trimethylhexan-2-ol

B.) Since there is a ketone (C=O) group in the molecule, the name should have the ending -one. Since the ketone takes priority, it is on the 2nd carbon. As such, there should be a 2 in front of the -one. The longest carbon chain contains 6 single-bonded carbons, making this a hexane. There is an ethyl (-CH₂CH₃) group on the 3rd carbon and a bromo (-Br) group on the 6th carbon.

Therefore, the IUPAC name is: 6-bromo-3-ethylhexan-2-one

C.) Since there is an aldehyde (HC=O) group in the molecule, the name should have the ending -al. Since the aldehyde is on the 1st carbon, you can add a 1 before the -al (technically not necessary). The longest carbon chain contains 8 single-bonded carbons, making this an octane. There is an isopropyl (-CHCH₃CH₃) group on the 3rd carbon and a propyl (-CH₂CH₂CH₃) on the 4th carbon.

Therefore, the IUPAC name is: 3-isoproyl-4-propyloctan-1-al (or 3-isoproyl-4-propyloctanal)

Answer:

Hexane is a 6-carbon hydrocarbon.

Cyclopentyl is a 5-carbon, hydrocarbon ring.

The 1- indicates that the cyclopentyl is attached to the first carbon in hexane.

Two ways of drawing the structure of 1-cyclopentylhexane are below:

Answer:

0.084 moles of H₂O

Explanation:

RAM of Mg = 24, of H = 1, of O = 16

Mg(OH)₂ + 2HCI --> MgCl2 + 2H₂O

Mole of Mg(OH)₂ = mass/MolarMass

= 1/24 = 0.042mol

From the equation,

1 mole of Mg(OH)₂ = 2 moles of H₂O

0.042mol of Mg(OH)₂ = 2 × 0.042 of H₂O

= 0.084 moles of H₂O