3. A certain Chemical Industry company has a quality control job opening. The job is open for any major with basic knowledge of chemistry. You decided to apply. In the interview the HR personnel gives you a sealed folder from a certain lot to test your laboratory experience, as well as your quantitative and volumetric analysis skills. The chemical contained in the sample is benzoic acid (C-H602) and it is known to be a monoprotic acid. In order to get the job, you need to determine if the sample's purity is acceptable based on their standards. Inside the folder you found a vial with a solid sample labeled BA-I, a periodic table, and the following data: 1.250 g of the sample required 20.15 mL of 0.500 M concentration of NaOH to reach the end point. The lot can be denied if the purity is below 99.5 % purity.

1) What is the purity in the sample?
2) Is it the purity acceptable?
3) Would you repeat the titration experiment?​

Answer:

Fe^2+(aq) = 4.51 × 10^-11 M

Fe3+(aq) = 1.79 × 10^5 M.

Explanation:

So, the first thing to do is to to write out the chemical reaction showing the ionic reaction of the chemical species present in the chemical reaction;

4Fe^2+ (aq) + O2(g) + 4H^+ <---------------------------> 4Fe^3+(aq) + 2H2O(l).

The next thing to do is to determine or calculate for G° and the equilibrium constant,kc. Thus, the value of G° = 4(-4.6) + 2(-237.18) - {4(-78.87)} = -177.28 kJ/mol.

Therefore, the equilibrium constant = e^-∆G°/RT = 1.19 × 10^31.

Therefore the value for Fe^2+ and Fe^3+ can be determine as;

NB=> Recall that [Fe^3+]/[Fe^2+] = kc [(Po2) (H^+)^4]^1/4.

Also, 1/ 55850 = 1.79 × 10^-5 M.

[Fe^2+] + [Fe^3+] = 1.79 × 10^-5. -------(1).

Therefore, [Fe^3+]/[Fe^2+] = kc [(Po2) (H^+)^4]^1/4. = [Fe^3+]/[Fe^2+] = [ 1.19 × 10^31 × 0.2095 × (10^2)^2] ^1/4 = 3.97 × 10^5.

Therefore, [Fe^3+]/[Fe^2+] = 3.97 × 10^5.

[Fe^3+] = 3.97 × 10^5[Fe^2+].

Hence, using the equation (1) above we can determine the value of the species.

[Fe^2+] + [Fe^3+] = 1.79 × 10^-5

[Fe^2+] + [Fe^2+] = 1.79 × 10^-5.

[Fe^2+] + 3.97 × 10^5[Fe^2+] = 1.79 × 10^-5.

[Fe^2+] = 4.51 × 10^-11 M.

Therefore, we will have [Fe^3+]/[Fe^2+] = 3.97 × 10^5.

Thus, [Fe^3+] = [Fe^2+] × 3.97 × 10^5. = 1.79 × 10^5 M.

The phase change that results in an increase in entropy is the change; Br2(1) - Br2(g)

The term entropy refers to the degree of disorderliness in a system. We have to note that gases have a higher entropy than liquids and liquids have a higher entropy than the solids.

As such, the phase change that results in an increase in entropy is the change; Br2(1) - Br2(g)

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Answer:

C) F

Explanation:

Valence electrons are the electrons present in the outermost shell of an atom and have the highest energy level of an atom whereas electrons at ground state or lower orbitals have less potential energy.

This is so because orbitals nearby nucleus are strongly bonded with the atomic nucleus and have less energy than an outermost shell.

So, the potential energy states of an atom depend on the number of orbitals. In the given options fluorine with atomic number 9 has less number of orbitals that is 2 orbitals and valence electrons will be present in second orbitals, so fluorine will have the lowest average potential energy states.

Hence, the correct option is "C) F".

Answer:

I think is is D cause none of the other ones seen right

Answer:

The answer is D. The 2s subshell can hold more electrons

Answer:

27

Explanation: volume-3 times 6=18 /mass- 81 times 6= 486....  486 divided by 18 = 27.... a cube has 6 sides.

The density of a substance is simply defined as the mass of the subtance per unit volume of the substance.

[tex]Density = \frac{Mass }{Volume }[/tex]

To obtain the density of the aluminum, we'll begin by calculating the volume of the aluminum. This can be obtained as follow:

From the question given above, each side of the aluminum cube measures 3 cm. Thus,

Length (L) = 3 cm

Width (W) = 3 cm

Height (H) = 3 cm

Volume = Length × Width × Height

Volume = 3 × 3 × 3

Therefore, the volume of the aluminum is 27 cm³

Finally, we shall determine the density of the aluminum. This can be obtained as follow:

Mass = 81 g

Volume = 27 cm³

[tex]Density = \frac{Mass }{Volume }\\\\Density = \frac{81}{27}[/tex]

Therefore, the density of the aluminum is 3 g/cm³

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Answer:

1.68% is ionized

Explanation:

The Ka of benzoic acid, C₇H₆O₂, is 6.46x10⁻⁵, the equilibrium in water of this acid is:

C₇H₆O₂(aq) + H₂O(l) ⇄ C₇H₅O₂⁻(aq) + H₃O⁺(aq)

Ka = 6.46x10⁻⁵ = [C₇H₅O₂⁻] [H₃O⁺] / [C₇H₆O₂]

Where [] are concentrations in equilibrium

In equilibrium, some 0.225M of the acid will react producing both C₇H₅O₂⁻ and H₃O⁺, the equilibrium concentrations are:

[C₇H₆O₂] = 0.225-X

[C₇H₅O₂⁻] = X

[H₃O⁺] = X

Replacing:

6.46x10⁻⁵ = [X] [X] / [0.225-X]

1.4535x10⁻⁵ - 6.46x10⁻⁵X = X²

1.4535x10⁻⁵ - 6.46x10⁻⁵X - X² = 0

Solving for X:

X = -0.0038. False solution, there is no negative concentrations.

X = 0.00378M. Right solution.

That means percent ionization (100 times Amount of benzoic acid ionized  over the initial concentration of the acid) is:

0.00378M / 0.225M * 100 =

Explanation:

no of moles = no of atoms ÷ avogadro's number

= (9.8×10^24) ÷ (6.02×10^23)

Answer:

ZnCl2

sodium iodide

ammonium carbonate

Pb(NO3)2

Explanation:

Substances that dissolve in water can be accurately determined using the solubility rules.

According to the solubility rules, all nitrates are soluble. This implies that lead II nitrate is also soluble in water.

Similarly, all chlorides are soluble in water hence ZnCl2 is soluble in water.

Sulphates are soluble except those of Pb, Ba, Ca and Mg.

Also, NaI is highly soluble in water.

Lastly, all carbonate salts are insoluble except those of sodium, potassium and ammonium. Hence ammonium carbonate is soluble in water.

Answer:

see explanation

Explanation:

When caffeine is purified, the impurities are removed,  these impurities are responsible for the greater mass of pure caffeine compared to the mass of the pure sample.

The percent recovery of caffeine is frequently low because some caffeine is often left behind in the solvent during the process of recrystallization.

Secondly, since caffeine is a sublime substance, some caffeine may be lost o sublimation leading to a low percent recovery of pure caffeine.

The question is incomplete, the complete question is;

Compare Homogeneous and Heterogeneous Equilibria Question Which type of equilibrium is more likely to omit substances from the equilibrium constant expression? Select the correct answer below: O homogeneous equilibria O heterogeneous equilibria O a and b are equally likely O there is no correlation

Answer:

heterogeneous equilibria

Explanation:

In a heterogeneous equilibria, there are species of different phases present in the equilibrium expression. Some of these heterogeneous substances may be pure solids.

Remember that the solids and pure liquids are eliminated from the final equilibrium expression.

Thus, when writing equilibria involving heterogeneous substances, solids and pure liquids do not appear in the final equilibrium expressions.

Answer:

Mark as brainleist answer and thanks this answer

Answer:

because they can create noise

Explanation:

sounds is through music or songs but vibration is just quick vibrate music, not quite sure , it's just my instinct, lol

Answer:

See explanation

Explanation:

When the temperature was increased, the pressure of the gas in the can was increased.

When Maria removed the can and placed it in cold liquid, the decrease in temperature led to a corresponding decrease in pressure of the gas inside the can hence the can was crushed.

Hypothesis: The pressure of the gas in the can is directly proportional to temperature.

Maria was careless about the experiment. She ought to have first checked whether the hot plate was off before placing the soda can. Secondly,she should not have immediately plunged the soda can into liquid because it will shrink due to decrease in pressure. She should not also have removed the soda can with bare hands to avoid getting burns and blisters.

Answer:

CaSO₄ (calcium suflate) is the precipitate formed

Explanation:

We can think the reactants:

BeSO₄ → Beryllium sulfate

Ca(OH)₂ → Calcium hydroxide

The reaction is:

Be₂SO₄  +  Ca(OH)₂  →  CaSO₄ ↓  +  Be(OH)₂

We call it as a double-replacement reaction because two ions exchange places from 2 compounds to form two new compounds.

Sulfates can always make precipitate with the elements from group 2, Ca, Ba and Mg.  

Hydroxides from group 2 are solubles, so we complete states:

BeSO₄ (aq)  +  Ca(OH)₂ (aq)  →  CaSO₄ ↓ (s)  +  Be(OH)₂ (aq)

Answer:

C renewable

Explanation:

because renewable energy repleneshes itself, therefore the quickest

Renewable resources are replenished MORE quickly than they are used (option C).

In conclusion, renewable resources are replenished MORE quickly than they are used (option C).

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Answer:

0.41g/L

Explanation:

To find the concentration of the albumin in the mixture we need to find the mass in grams and the volume in liters of the solution:

Mass of albumin:

0.20x10⁻³L * (6.0g / L) = 1.2x10⁻³g of albumin

Volume of the solution:

0.20mL + 2.72mL = 2.92mL = 2.92x10⁻³L

Thus, concentration of albumin is:

1.2x10⁻³g of albumin / 2.92x10⁻³L =

Answer:

From these two values, i.e. mass and volume, density of the copper cylinder can be calculated.

Formula of density is :

Density = Mass / volume.

Now we have mass: 53.76g and volume 6cm³

Density = 53.76 / 6

Density= 8.96 g/cm³

The answer should be 37,000,000

Answer:

c atomic numbers

Explanation:

hope this helps

Answer:

atomic numbers

Explanation:

In order for two atoms to be different, they have to have a different number of protons. Protons are represented by the atomic number. Thus, atoms of two DIFFERENT elements must have different atomic numbers.

I took the test and got 100%

Hope this helps!

Answer: A) A theory is the best possible explanation based on all existing evidence

A law in physics and chemistry is a description of what is going on. For instance, newton's law of motion helps us find out an objects acceleration if we know its mass and the force applied. The theory of gravity on the other hand is the best guess we make as to why objects with mass are attracted to one another.

Theories change over time if new evidence is found that contradicts the old theory. Saying "a theory is more important than a law" is subjective, and I would argue that both are equally important in their own way.

The atomic theory a theory is the best possible explanation based on all existing evidence. The correct option is A.

The word theory renowned as to an untested hunch or one can say a guess with not having a supporting evidence.

A theory, has nearly the opposite implications for scientists. A theory is a well-supported explanation of an innate phenomenon that can encompass laws, hypotheses, along with facts.

Theories are developed to elaborate, predict, as well as comprehend phenomena, also to challenge and extend existing understanding within the constraints of critical boundary assumptions.

A theory does not become a scientific law as new or better evidence accumulates.

The theories are explanations, as well as laws are patterns located in large amounts of data that are frequently expressed as an equation. A theory will always be a theory in all aspect, and a law will always be a law.

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The mass number of an element is the sum of the protons and neutrons present in the nucleus of the atoms of the element.

The mass number of an element is the number obtained when the number of protons and neutrons in the nucleus of an atom of the element are summed together.

The sum of protons and neutrons in the nucleus of an atom is collectively known as the nucleon. Thus, the mass number of an atom can also be referred to as the nucleon of the atom.

This can be mathematically expressed as:

Mass number = number of protons + number of neutrons.

Atoms generally contain protons, neutrons, and electrons. The protons are positively charged and are located in the nucleus, the neutrons are also located in the neucleus but have no charges. The electrons, on the other hand, are located outside the nucleus in regions referred to as orbitals.

The sum of the protons and neutrons determine the mass of an atom because the contribution of electrons to the mass of atoms is negligible.

Thus, the mass number of an element is the sum of proton and neutron numbers present in the nucleus of the atoms of the element.

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Answer: The simplest and most common type is a single bond in which two atoms share two electrons. Other types include the double bond, the triple bond, one- and three-electron bonds, the three-center two-electron bond and three-center four-electron bond. ... Bonds within most organic compounds are described as covalent.

Explanation:

Answer:

21 is the max but with the bread ypu could make 22 if you had 3 more cheese

Answer:

left to right across a period when it decreases and when it increases top to bottom in a group,

hope i helped

Answer:

43.75 ml

Explanation:

Given that the equation of the reaction is;

2HNO3(aq) + Ca(OH)2(aq) ---> Ca(NO3)2(aq) + 2 H20(l)

Concentration of acid CA= 0.05 M

Concentration of base CB = 0.02 M

Volume of acid VA = 35.00ml

Volume of base VB= ???

Number of moles of acid NA= 2

Number of moles of base NB=1

From

CAVA/CBVB= NA/NB

Making VB the subject of the formula;

VB= CAVANB/CBNA

VB= 0.05 × 35 × 1/ 0.02 × 2

VB=1.75 /0.04

VB= 43.75 ml

Answer:

Strong electrolytes-2,4

Weak electrolyte-1,5

Non electrolyte- 3,6

Explanation:

The statements were labeled according to whether they define strong electrolytes, weak electrolytes or non electrolytes.

Strong electrolytes are completely dissociated in solution and form highly ionic solutions.

Weak electrolytes have medium conductivity and do not completely dissociate in solution.

Non electrolytes do not dissociate in solution and their solution does not conduct electricity.

1. Weak electrolyte solution: it contains a partially dissociated solute.

2. Strong electrolyte solution: it has the highest conductivity.

3. Non-electrolyte solution: it contains a complete solute.

4. Strong electrolyte solution: it contains a completely dissociated solute.

5. Weak electrolyte solution: it has a medium level of conductivity.

6. Non-electrolyte solution: it has little or no conductivity.

A solution can be defined as a homogenous mixture that contains two or more substances.

In Chemistry, there are three (3) main types of solution and these include:

1. Weak electrolyte solution: this is a type of solution in which only a small amount of dissolved solute exists as ions because it partially dissociates into its constituent anions and cations.

2. Strong electrolyte solution: this is a type of solution that contains only ions but no molecules of the electrolyte because it completely dissociates or ionizes in a solution.

3. Non-electrolyte solution: this is a type of solution that do not dissociates or ionizes in a solution.

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Answer:

Be2^+

Explanation:

Ionic diameter increases down the group. This implies that Be2^+ will have the smallest diameter.

This extremely small diameter makes Be2^+ to differ considerably from other ions of group 2 elements.

For instance, the compounds of beryllium are mostly covalent in nature.