A scientist makes a measurement and gets a value of 13.1 m. The true value is 10.0 m. Calculate the absolute and relative error of the scientist's measurement. Round your answers to a reasonable number of decimal places. Also be sure your answers include any necessary symbols.

This is an incomplete question, here is a complete question.

The heat of combustion of bituminous coal is 2.50 × 10² J/g. What quantity of the coal is required to produce the energy to convert 106.9 pounds of ice at 0.00 °C to steam at 100 °C?

Specific heat (ice) = 2.10 J/g°C

Specific heat (water) = 4.18 J/g°C

Heat of fusion = 333 J/g

Heat of vaporization = 2258 J/g

A) 5.84 kg

B) 0.646 kg

C) 0.811 kg

D) 4.38 kg

E) 1.46 kg

Answer : The correct option is, (A) 5.84 kg

Explanation :

The process involved in this problem are :

[tex](1):H_2O(s)(0^oC)\rightarrow H_2O(l)(0^oC)\\\\(2):H_2O(l)(0^oC)\rightarrow H_2O(l)(100^oC)\\\\(3):H_2O(l)(100^oC)\rightarrow H_2O(g)(100^oC)[/tex]

The expression used will be:

[tex]Q=[m\times \Delta H_{fusion}]+[m\times c_{p,l}\times (T_{final}-T_{initial})]+[m\times \Delta H_{vap}][/tex]

where,

[tex]Q[/tex] = heat required for the reaction = ?

m = mass of ice = 106.9 lb = 48489.024 g      (1 lb = 453.592 g)

[tex]c_{p,l}[/tex] = specific heat of liquid water = [tex]4.18J/g^oC[/tex]

[tex]\Delta H_{fusion}[/tex] = enthalpy change for fusion = [tex]333J/g[/tex]

[tex]\Delta H_{vap}[/tex] = enthalpy change for vaporization = [tex]2258J/g[/tex]

Now put all the given values in the above expression, we get:

[tex]Q=145903473.2J[/tex]

Now we have to calculate the quantity of the coal required.

[tex]m=\frac{Q}{\Delta H}[/tex]

[tex]m=\frac{145903473.2J}{2.50\times 10^4J/g}[/tex]

[tex]m=5836.138929g=5.84kg[/tex]      (1 g = 0.001 kg)

Thus, the quantity of the coal required is, 5.84 kg

Answer:

hydrogen Flouride, hydrogen Tennesside

Explanation:

The strongest bond among hydrogen halides is found in hydrogen fluoride, while the longest bond is found in hydrogen iodide. This is due to the decreasing bond strength and increasing bond length with increasing size of the halide ion.

Among the hydrogen halides, the strongest bond is found in hydrogen fluoride (HF) and the longest bond is found in hydrogen iodide (HI). The bond strength in hydrogen halides typically decreases as the size of the halide ion increases, with fluorine being the smallest and therefore, the strongest. Conversely, the bond length increases with the size of the halide ion, hence why iodine, the largest halide, forms the longest bond with hydrogen.

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Answer:

See explanation below.

Explanation:

Dipoles are molecules that have partial charges. It happens because of the difference in electronegativity of the elements. This property is the tendency that the atom has to take the electron to it, so, in the covalent bond, the shared pair of electrons is easily found at the more electronegativity atom, and so, it has a partial negative charge, and the other, a partial positive charge. This is a natural dipole.

If the difference of electronegativity is 0, or extremely close to 0, then the molecule is nonpolar, and so the molecule doesn't have partial charges. But, to be joined together and form the substance, the partial charge must be induced, so it's an induced dipole.

Final answer:

An electric dipole consists of two opposite charges separated by a distance, and is seen in natural structures like water molecules. A permanent dipole is due to molecular structure, while an induced dipole occurs due to an external electric field. The dipole moment represents the strength and direction of this separation of charges.

Explanation:

An electric dipole consists of two equal but opposite charges separated by a distance. This model is crucial in understanding atomic and molecular interactions. A common example of a natural dipole is the water molecule. The unequal distribution of electron density throughout a molecule can lead to a positive end and a negative end, resulting in a dipole moment.

Natural vs. Induced Dipole

A permanent dipole is inherent within a molecule and results from an unequal distribution of electron density due to its molecular structure. In contrast, an induced dipole occurs when an external electric field influences a neutral atom or molecule, causing the displacement of charges and creating the dipole moment. The induced dipole moment will be aligned with the external electric field.

The strength and direction of an electric dipole are expressed by the dipole moment, a vector quantity that represents the size of the charge separation and the distance between the charges. The physical significance of the dipole moment lies in its alignment parallel to an external electric field and its role in decreasing the total electric field within the dipole region, which has applications in areas like capacitors.

Answer:

True

True

False

False

False

True

True

Explanation:

The recrystallization is a purification process, in which a solid with impurities is dissolved in a hot solvent. The substance must be soluble in the hot solvent, so the impurities can leave the solid crystal. Then, the solution is cold, until the crystals are formed again, thus, the substance can't be soluble in the cold solvent, because if so, the recrystallization will not happen. The crystals are then separated.

Let's check the statements:

The solvent should not dissolve the compound when cold.

As explained above, this is true.

The solvent should either dissolve the impurities at all temperatures or not dissolve the impurities at all.

The impurities must be separated from the crystal, so if the solvent dissolves it has higher, it should dissolve it when it's cold because if it didn't happen, the impurities will recrystallize too. If the solvent doesn't solubilize it when it is hot, so, the impurities crystal will be formed first, and when the solvent is cold it can dissolve it because the impurities can enter the crystal compound again. So, it's true.

The solvent should not dissolve the compound while hot.

As explained above, the solvent must dissolve the compound while hot, so it's false.

The solvent should chemically react with the compound.

If the solvent reacts with the compound, a new substance will be formed, and the purification will not happen. So, it's false.

The solvent should dissolve the compound while cold.

As explained above, the compound must be solid in the cold solvent, so it's false.

The solvent should not chemically react with the compound.

As explained above, this is true.

The solvent should dissolve the compound while hot.

As explained above, this is true.

Answer:

Hi

The Fermi Level is a term used to describe the set of electron energy levels at a temperature of absolute zero. Fermi's energy concept is important for the understanding of the electrical and thermal properties of solids. Both electrical and thermal processes involve energy values of a small fraction of an electron-volt. In thermal equilibrium, the net current of both electrons and holes is zero.

Explanation:

Under equilibrium conditions, the probability of an electron state being occupied if it is located at the Fermi level is 50 percent probability.

Fermi Level is the term that is used to define the highest or most optimal energy level that an electron can occupy when the temperature is at absolute zero.

The Fermi level is equidistant between the valence band and conduction band. This is because when the temperature is at absolute zero, the electrons are all in the lowest state of energy.

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Explanation:

For a compound to show hydrogen bonding it is necessary that the hydrogen atom of the compound should be attached to more electronegative atom like fluorine, oxygen or nitrogen.

For example, [tex]CH_{3}CH_{2}OH[/tex], [tex]CH_{3}NH_{2}[/tex] and [tex]NH_{3}[/tex] all these compounds contain an electronegative atom attached to hydrogen atom.

Therefore, these pure compounds will exhibit hydrogen bonding.

Thus, we can conclude that out of the given options [tex]CH_{3}CH_{2}OH[/tex], [tex]CH_{3}NH_{2}[/tex] and [tex]NH_{3}[/tex] are the pure compounds which will exhibit hydrogen bonding.

Answer:

2-methoxybutane

Explanation:

This reaction is an example of Nucleophilic substitution reaction. Also, the reaction of (S)-2-bromobutane with sodium methoxide in acetone, is bimolecular nucleophilic substitution (SN2). The reaction equation is given below.

(S)-2-bromobutane + sodium methoxide (in acetone) → 2-methoxybutane

Answer: 1.14

Explanation:

[tex]HCl+NaOH\rightarrow NaCl+H_2O[/tex]

To calculate the molarity of acid, we use the equation given by neutralization reaction:

[tex]n_1M_1V_1=n_2M_2V_2[/tex]

where,

[tex]n_1,M_1\text{ and }V_1[/tex] are the n-factor, molarity and volume of acid which is [tex]HCl[/tex]

are the n-factor, molarity and volume of base which is NaOH.

We are given:

[tex]n_1=1\\M_1=?\\V_1=10.0mL\\n_2=1\\M_2=0.1M\\V_2=7.2mL[/tex]

Putting values in above equation, we get:

[tex]1\times M_1\times 10.0=1\times 0.1\times 7.2\\\\M_1=0.072M[/tex]

To calculate pH of gastric juice:

molarity of [tex]H^+[/tex] = 0.072

[tex]pH=-log[H^+][/tex]

[tex]pH=-log(0.072)=1.14[/tex]

Thus the pH of the gastric juice is 1.14

The pH of the gastric juice is 1.14

We'll begin by calculating the molarity of the HCl needed for the reaction.

HCl + NaOH —> NaCl + H₂O

From the balanced equation above,

The mole ratio of the acid, HCl (nA) = 1

The mole ratio of the base, NaOH (nB) = 1

Molarity of base, NaOH (Mb) = 0.1 M

Volume of base, NaOH (Vb) = 7.2 mL

Volume of acid, HCl (Va) = 10 mL

MaVa / MbVb = nA/nB

(Ma × 10) / (0.1 × 7.2) = 1

(Ma × 10) / 0.72 = 1

Cross multiply

Ma × 10 = 0.72

Divide both side by 10

Ma = 0.72 / 10

HCl (aq) —> H⁺(aq) + Cl¯(aq)

From the balanced equation above,

1 mole of HCl contains 1 mole of H⁺.

Therefore,

0.072 M HCl will also contain 0.072 M H⁺

Hydrogen ion concentration, [H⁺] = 0.072 M

pH = –Log [H⁺]

pH = –Log 0.072

Thus, the pH of the gastric juice is 1.14

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Answer:

5.426 x 10⁹ g

5.55 mol

Explanation:

This type of problems involve the use of proportions , and the use of conversion of units to solve them.

In the first part we have to determine the mass in grams of a mole of virus, so we have to convert the mass to grams and  multiply by avogadro´s number.

9.010x 10⁻¹² mg x  ( 1 g / 1000 mg ) = 9.010 x 10⁻¹⁵ g

mass of 1 mol viruses:

9.010 x 10⁻¹⁵ g/ virus x ( 6.022 x 10²³ virus/mol ) = 5.426 x 10⁹ g /mol

(Note we rounded to 4 significant figures since 9.010 has 4 significant figures.)

For the second part convert the mass of the oil tanker to grams, and make use of the previous result to determine the # of moles of viruses which have the same mass.

mass oil tanker = 3.01 x 10⁷ Kg x ( 1000 g /Kg ) = 3.01 x 10¹⁰ g

3.01 x 10¹⁰ g x ( 1 mol virus / 5.426 x 10⁹ g ) = 5.55 mol

( Note here we rounded to three significant figures since in the multiplication we have 3.01 with three significant figures. )

The result is amazing and it is due to the very small mass of the virus. Imagine only 5.55 mol of virus in the same mass as that of an oil tanker !!!

Final answer:

The mass of one mole of viruses is 5.42 grams, calculated by converting the mass of a single virus to grams and then multiplying by Avogadro's number. To equate to the mass of an oil tanker, there would be 5.54 × 10^9 moles of viruses.

Explanation:

To calculate the mass of one mole of viruses, we use the given mass of a single virus and Avogadro's number. Since we have the mass of one virus as 9.0 × 10-12 mg, we first convert this mass to grams by dividing by 1,000,000 (since there are 1,000,000 micrograms in a gram), giving us 9.0 × 10-18 g. Then, we multiply this mass by Avogadro's number (6.022 × 1023 particles/mole) to get the mass of one mole of viruses: 5.42 g.

To find out how many moles of viruses have a mass equal to that of the oil tanker, we first convert the mass of the oil tanker to grams (3.0 × 107 kg is equal to 3.0 × 1010 g because there are 1,000 kg in a tonne and 1,000 g in a kg). Now, we divide this mass by the mass of one mole of viruses (5.42 g/mole), giving us: 5.54 × 109 moles.

Explanation:

It is known that 1 SCF produces approximately 1000 Btu of thermal energy.

As it is not mentioned for how many hours the gas is used in this process. Therefore, we assume that the total number of hours natural gas used in this process are as follows.

        [tex]365 \times 24[/tex] = 8760 hours

Now, we will calculate the annual cost of natural gas used in the process as follows.

               [tex]8760 \times 63400[/tex]

              = 555384000 SCF

Hence, annual cost of natural gas used in this process = loss of thermal energy

This will be equal to,  [tex]555384000 \times 1000[/tex]

                           = 555,384,000,000 BTU

Thus, we can conclude that the annual cost of natural gas used in the process is 555,384,000,000 BTU.

To calculate the annual cost of natural gas used in the process, multiply the hourly usage by the number of hours in a year and the cost per SCF. The total gives you an approximate annual expenditure.

The exact annual cost of natural gas usage of the said process will depend on the current cost per SCF (standard cubic foot) of natural gas, which can fluctuate throughout the year based on economic conditions and demand. If you know the cost per SCF, you can calculate the annual cost by multiplying the hourly usage (63,400 SCF/h) by the number of hours in a year (8,760 hours), then multiply that result by the cost per SCF.

For instance, if natural gas cost $0.01 per SCF, your annual cost would be 63,400 SCF/hr * 8,760 hours * $0.01/SCF. This would give you an approximate annual expense for natural gas used in the process. However, it's prudent to cross-check this number with those in your bills and other related documents whenever practical.

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Answer:

[Cl₂] in equilibrium is 1.26 M

Explanation:

This is the equilibrium:

PCl₃(g) + Cl₂(g) ⇋ PCl₅(g)

Kc = 91

So let's analyse, all the process:

                PCl₃(g)        +        Cl₂(g)     ⇋        PCl₅(g)

Initially     0.24 M                 1.50M                 0.12 M

React           x                           x                         x

Some amount of compound has reacted during the process.

In equilibrium we have

              0.24 - x                  1.50 - x                  0.12 + x

As initially we have moles of product, in equilibrium we have to sum them.

Let's make the expression for Kc

Kc = [PCl₅] / [Cl₂] . [PCl₃]

91 = (0.12 + x) / (0.24 - x) ( 1.50 - x)

91 = (0.12 + x) / (0.36 - 0.24x - 1.5x + x²)          

91 (0.36 - 0.24x - 1.5x + x²) = (0.12 + x)

32.76 - 158.34x + 91x² = 0.12 +x

32.64 - 159.34x + 91x² = 0

This a quadratic function:

a = 91; b= -159.34; c = 32.64

(-b +- √(b² - 4ac)) / 2a

Solution 1 = 1.5

Solution 2 = 0.23 (This is our value)

So [Cl₂] in equilibrium is 1.50 - 0.23 = 1.26 M

Answer:

pH = 4.8

Explanation:

We will use the Henderson-Hasselbach equation to calculate the pH of the buffer:

pH = pKₐ + log [A⁻]/[HA]

From the information given:

pKₐ = 3.86

[A⁻] =  0.100 M

[HA] = 0.020 M

Plugging our values:

pH = 3.86 + log ( 0.100/0.020 ) = 4.6

For part b the same equation is utilized.

However we have to realize that the concentrations of the acid and its conjugate base have changed according to the neutralization reaction :

NaOH + lactic acid ⇒ sodium lactate + H₂O

# mol NaOH reacted = (8.0 mL x 1 L / 1000 mL ) x 1.00 M

= 8.0 x 10⁻³ mol

mol  sodium lactate produced = 8.0 x 10⁻³ mol   ( 1:1 )

number of moles mol lactic acid   originally = 1 L x 0.020 mol/L = 0.020 mol

new mol lactic acid after reaction = 0.020 - 8.0 x 10⁻³ =  0.012 mol

new mol sodium lactate after reaction = 0.100 mol/L x 1 L + 8.0 x 10⁻³ = 0.108

Here we do not need to calculate the new concentrations since molarity  is mol/V, and  the volumes cancel each other in the Henderson-Hasselbach equation because  they are in a ratio.

Now we are in position to determine the pH.

pH = 3.86 + log ( 0.108/0.012 ) = 4.8

This the usefulness of buffers, we are adding a 1.00 M  strong base NaOH, and the pH did not change that much (  a long as they are small additions within reason )

Answer:

Reversible Processes:

- solid melting infinitesimally slowly at its melting point

- gas condensing infinitesimally slowly at its condensation point

- a single swing of frictionless pendulum

- liquid vaporizing infinitesimally slowly at its boling point

- liquid freezing infinitesimally slowly at its freezing point

Irreversible Processes:

- a single swing of a real pendulum

- solid melting infinitesimally slowly above its melting point

- liquid freezing below its freezing point

- gas condensing below its condenation point

- liquid vaporizing above its boiling point

Explanation:

Hint to help solve: "spontaneous processes, such as a solid melting above its melting point, are not reversible according to the scientific definition. Certainly one could place the melted substance in a cold environment and it would freeze again, but the surroundings would not be restored to their original state before melting and, in fact, would be further altered in the cooling process" - Mastering Chem.

Answer:

Brønsted-Lowry acid : H2SO4, HF, HNO2

Brønsted-Lowry Base : NH3, C3H7NH2, CH3)3N

Neither : NaBr, CCl4

Explanation:

H2SO4, HNO2, and HF are Brønsted-Lowry acids. (CH3)3N, C3H7NH2, and NH3 are Brønsted-Lowry bases. NaBr and CCl4 are neither.

In the Brønsted-Lowry definition, an acid is a substance that can donate a proton (H+) and a base is a substance that can accept a proton. Looking at your list:

 NaBr and CCl4 are neither Brønsted-Lowry acids nor bases since they do not participate in proton donation or acceptance.  

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Answer: Mass of one mole of viruses in grams is [tex]54\times 10^{8}[/tex]  

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to molecular mass and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

Given : One virus has mass of = [tex]9.0\times 10^{-12}mg=9.0\times 10^{-15}g[/tex]     [tex]1mg=10^{-3}g[/tex]

One mole of virus [tex]6.023\times 10^{23}[/tex] has mass of = [tex]\frac{9.0\times 10^{-15}}{1}\times 6.023\times 10^{23}=54\times 10^{8}g[/tex]  

Thus mass of one mole of viruses in grams is [tex]54\times 10^{8}[/tex]  

To find the mass of one mole of viruses in grams, convert the given mass of a virus from mg to grams and then multiply it by Avogadro's number, 6.022 × 10^23 particles/mol.

The mass of one mole of viruses can be calculated by converting the given mass of a virus to grams and then multiplying it by Avogadro's number, which represents the number of particles in one mole. Avogadro's number is approximately 6.022 × 10^23 particles per mole.

First, we convert the given mass of a virus from mg to grams:

9.010 × 10^-12 mg = 9.010 × 10^-15 g

Next, we multiply the mass of one virus by Avogadro's number:

9.010 × 10^-15 g × 6.022 × 10^23 particles/mol =

5.42 × 10^9 g

Therefore, the mass of one mole of viruses is approximately 5.42 × 10^9 grams.

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Answer:

Option I. E2 and SN1

Explanation:

First, let's discard the options.

Option II cannot be because sodium ethoxide, although is a good nucleophyle, it's also a strong base, so it can take place a acid base reaction, and ethoxide act as base to substract an electrophyle from the iodohexane, therefore, it can go through a mechanism of elimination.

Option III cannot be either because the above explanation. Also a reaction in basic conditions can actually go through bimolecular reactions, so it has to be E2 only. E1 is in acidic conditions mostly and involves a carbocation, which in basic medium cannot be.

Because of the above explanation, option IV cannot be either.

Technically option 1 cannot be either because a reaction if it's bimolecular, then it has to be Sn2 and E2 only.

but it's the only option that has sense above all.

The mechanism is as follow:

The branch of science which deals with chemicals and bonds is called chemistry.

The correct option is A

The other option is wrong because of the following reason:-

Hence, the correct option is 1 that is E2 +SN1

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Answer:

0.08 mL

Explanation:

The solution of the skin test has a concentration of 0.2% (w/v), which means that there are 0.2 g of the antigen per 100 mL of the solution. If a new solution will be done using it, then this solution will be diluted, and the mass of the antigen added must be the same in the volume taken and at the diluted solution.

The mass is the concentration (in g/mL) multiplied by the volume of the solution (in mL), so, if m is the mass, C the concentration, V the volume, 1 the initial solution, and 2 the diluted:

m1 = m2

C1*V1 = C2*V2

Where

C1 = 0.2 g/100 mL = 0.002 g/mL

V1 = ?

C2 = 0.04 mg/mL = 0.00004 g/mL

V2 = 4 mL

0.002*V1 = 0.00004*4

V1 = 0.08 mL

Considering the definition of dilution, 0.08 mL of a 0.2% solution of a skin test antigen must be used to prepare 4 mL of a solution containing 0.04 mg/mL of the antigen.

First of all, you have to know that when it is desired to prepare a less concentrated solution from a more concentrated one, it is called dilution.

Dilution is the process of reducing the concentration of solute in solution, which is accomplished by simply adding more solvent to the solution at the same amount of solute.

In a dilution the amount of solute does not change, but as more solvent is added, the concentration of the solute decreases, as the volume (and weight) of the solution increases.

A dilution is mathematically expressed as:

Ci×Vi = Cf×Vf

where

In this case, you know:

Replacing in the definition of dilution:

0.002 [tex]\frac{g}{mL}[/tex] × Vi= 0.00004 [tex]\frac{g}{mL}[/tex]× 4 mL

Solving:

[tex]Vi=\frac{0.00004 \frac{g}{mL}x4 mL}{0.002\frac{g}{mL} }[/tex]

Vi= 0.08 mL

In summary, 0.08 mL of a 0.2% solution of a skin test antigen must be used to prepare 4 mL of a solution containing 0.04 mg/mL of the antigen.

Learn more about dilution:

Answer:

Explanation:

to begin, three steps are highlighted below which are used to write the Lewis structures of the given compounds, viz;

the image below gives a step by step explanation as to answering this question.

i hope this was helpful, cheers.

Drawing Lewis structures entails representing the arrangement of electrons in a molecule, observing the octet rule, and assigning formal charges. The formal charge is the hypothetical charge an atom would possess if electrons in bonds are evenly distributed. The negative formal charges are preferably located on the most electronegative atoms in the molecule or ion when there are multiple possible structures.

Drawing Lewis structures and assigning formal charges requires an understanding of the octet rule and the nature of the molecules. Lewis structures depict the arrangement of electrons in a molecule, particularly illustrating the bonding between atoms and the lone pairs of electrons that may exist. The octet rule suggests that atoms are stable when their outermost (valence) shell is full, typically with eight electrons.

The formal charge on an atom in a molecule is the hypothetical charge the atom would have if we could redistribute the electrons in the bonds evenly between the atoms. We calculate formal charge as follows: Formal Charge = [# of valence electrons on atom] – [non-bonded electrons + number of bonds]. Lewis structures are most reliable when adjacent formal charges are zero or of the opposite sign, and if there are several possible structures for a molecule or ion, the one with the negative formal charges on the more electronegative atoms is often the most accurate.

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Answer:

The answer is 10 electrons

Explanation:

From periodic table its possible to find

Nitrogen atom has 5 VE (Valence)  

Hydrogen atom has 1 VE (Valence)

Carbon atom has 4 VE ( Valence)

5+1+4=10 Electrons

The Lewis structure of a covalent compound containing one nitrogen atom, one hydrogen atom, and one carbon atom would contain 10 electrons. This is calculated by summing up the valence electrons of each atom: nitrogen (5), hydrogen (1), and carbon (4).

The Lewis structure of a covalent compound represents the arrangement of atoms and the bonding electrons. In this case, we have one nitrogen atom, one hydrogen atom, and one carbon atom. Nitrogen has 5 valence electrons, hydrogen has 1, and carbon has 4. Altogether, the Lewis structure of this covalent compound should contain 10 electrons.

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Answer : The correct option is, (C) 10-mL volumeric pipet.

Explanation :

Graduated cylinder : It is a measuring cylinder that is used to measure the volume of a liquid. It has a narrow cylindrical shape. The marked line drawn on the graduated cylinder shows the amount of liquid that has been measured.

Pipet : It is a type of laboratory equipment that is used to measure the volume of a liquid. It is small glass tube and the marked line drawn on the pipet. It is used to accurately measure and transfer of volume of liquid from one container to another.

Volumetric flask : It is a type of laboratory tool that is also used for measuring the volume of liquid. It is used to make up a solution to a known volume. It measure volumes much more precisely than beakers.

Beaker : It is a type of laboratory equipment that has cylindrical shape and it is used for the mixing, stirring, and heating of chemicals.

As per question, we conclude that the pipet is most precise than other devices because in pipet the marking lines are more accurate. Thus, it can be used to measure volume to precision.

Hence, the correct option is, (C) 10-mL volumeric pipet.

Answer:

a) 25 vials

b) 3 vials

c) 3 bags

Explanation:

When a concentrated solution is diluted to form another solution, the new concentration can be calculated by:

C1V1 = C2V2

Where C is the concentration, V is the volume, 1 represents the initial solution, and 2 the final solution. The multiplication CV is constant because it represents the amount of matter in the solution which will not be changed.

a) Let's identify the volume (V1) needed when the concentrated solution has C1 = 0.5%, and the final solution has C2 = 0.125% and V2 = 100 mL

0.5*V1 = 0.125*100

0.5V1 = 12.5

V1 = 25 mL

Thus, this is the volume for 1 bag, for 30 bags, V = 30*25 = 750 mL. The vials needed is the volume divided by the volume of one vial:

750/30 = 25 vials.

b) Doing the same thing, now with C1 = 50 mg/mL, C2 = 1 mg/mL, and V2 = 100 mL:

50*V1 = 1*100

V1 = 2 mL

The volume for 30 bags is then 30*2 = 60 mL. The number of vials is:

60/20 = 3 vials.

c) In this case, the concentration of sodium chloride is the same in both solutions. Thus, the volume of it is the total volume of the bag (100 mL) less the volume of the other substances:

100 - 25 - 2 = 73 mL

The volume for 30 bags is 30*73 = 2190 mL. Thus, if the concentrated bag has 1 L = 1000 mL, the bags needed are:

2190/1000 = 2.19

Thus, 3 bags are needed (the 3rd bag will not be totally used!).

Answer:

The empirical formula is C3H4O

Explanation:

Step 1: Data given

Mass of the compound = 1.000 grams

The compound contains:

- Carbon

- hydrogen

- oxygen

The combustion of this compound gives:

2.360 grams of CO2

0.640 grams of H2O

Step 2: Calculate moles CO2

Moles CO2 = mass CO2 / molar mass CO2

Moles CO2 = 2.360 grams / 44.01 g/mol

Moles CO2 = 0.05362 moles

In CO2 we have 1 mol

This means for 1 mol CO2 we have 1 mol C

For 0.05362 moles CO2 we have 0.05362 moles C

We have 0.05362 moles of C in the compound  

Step 3: Calculate mass of C

Mass C = moles C * molar mass C

Mass C = 0.05362 moles * 12.0 g/mol

Mass C = 0.643 grams  

Step 4: Calculate moles of H2O  

Moles H2O = 0.640 grams / 18.02 g/mol

Moles H2O =  0.0355 moles H2O

For 1 mol H2O we have 2 moles of H

For 0.0355 moles H2O we have 2*0.0355 =  0.071 moles H  

Step 5: Calculate mass of H

Mass H = moles H * molar mass H

Mass H = 0.071 moles * 1.01 g/mol

Mass H = 0.072 grams

Step 6: Calculate mass of O

Mass of O = Mass of compound - mass of C - mass of H

Mass of O = 1.000 g - 0.643 - 0.072 = 0.285 grams

Step 7: Calculate moles of O

Moles O = 0.285 grams / 16.0 g/mol

Moles O = 0.0178 moles

Step 8: Calculate mol ratio

We divide by the smallest amount of moles

C:  0.05362 / 0.0178 = 3

H: 0.071 / 0.0178 = 4

O: 0.0178/0.0178 = 1

The empirical formula is C3H4O

The study of chemicals and bonds is called chemistry.

The correct answer is C3H4O

All the data is given in the question, these data is as follows:-

The compound contains:

The combustion of this compound gives:

The formula to calculate the moles is as follows:-

[tex]Moles CO2 = \frac{mass}{molar mass}[/tex]

[tex]Moles \ CO2 = \frac{2.360} {44.01} Moles\ CO2 = 0.05362 moles [/tex]

In CO2 we have 1 mole, Which means for 1 mole CO2 we have 1 mole Carbon. For 0.05362 moles CO2, we have 0.05362 moles Carbon, We have 0.05362 moles of C in the compound  

lets calculate the mass of C

Mass C = moles C * molar mass C

Mass C = [tex]0.05362 moles * 12.0 g/mol[/tex]

Mass C = 0.643 grams  

The moles of H2O is as follows

Moles H2O = [tex]\frac{0.640}{18.02} [/tex]

Moles H2O = 0.0355 moles H2O

For 1 mole H2O, we have 2 moles of H. For 0.0355 moles H2O we have 2*0.0355 =  0.071 moles H  

let's Calculate the mass of H

Mass H = moles H * molar mass H

Mass H = 0.071 moles * 1.01 g/mol

Mass H = 0.072 grams

let's Calculate mass of O

Mass of O = Mass of compound - mass of C - mass of H

Mass of O = 1.000 g - 0.643 - 0.072 = 0.285 grams

let's Calculate moles of O

Moles O = 0.285 grams / 16.0 g/mol

Moles O = 0.0178 moles

The mole ratio is as follows:-

We divide by the smallest amount of moles

C:  0.05362 / 0.0178 = 3

H: 0.071 / 0.0178 = 4

O: 0.0178/0.0178 = 1

Hence, The empirical formula is C3H4O

For more information about the empirical formula, refer to the link:-

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The question is incomplete, complete question is:

371 mg of an unknown protein are dissolved in enough solvent to make  5.00 mL of solution. The osmotic pressure of this solution is measured to be 0.118 atm  at 25°C .

Calculate the molar mass of the protein. Be sure your answer has the correct number of significant digits.

Answer:

The molar mass of unknown protein is 15,384.43 g/mol.

Explanation:

To calculate the molar mass of protein, we use the equation for osmotic pressure, which is:

[tex]\pi=icRT[/tex]

where,

[tex]\pi[/tex] = osmotic pressure of the solution = 0.118 atm

i = Van't hoff factor = 1 (for non-electrolytes)

c = concentration of solute = ?

R = Gas constant = [tex]0.0820\text{ L atm }mol^{-1}K^{-1}[/tex]

T = temperature of the solution = [tex]25^oC=[273+25]=298K[/tex]

Putting values in above equation, we get:

[tex]0.118 atm=1\times c\times 0.0821\text{ L.atm}mol^{-1}K^{-1}\times 298 K\\\\c=0.004823 mol/L[/tex]

[tex]concentration=\frac{Moles}{Volume (L)}[/tex]

[tex]0.004823 mol/L=\frac{n}{0.005 L}[/tex]

[tex]n=2.4115\times 10^{-5} mol[/tex]

To calculate the molecular mass of solute, we use the equation:

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

Moles of solute = [tex]2.4115\times 10^{-5} mol[/tex]

Given mass of solute = 371 mg = 0.371 g ( 1mg = 0.001 g)

Putting values in above equation, we get:

[tex]2.4115\times 10^{-5} mol=\frac{0.371 g}{\text{Molar mass of solute}}\\\\\text{Molar mass of solute}=15,384.43 g/mol[/tex]

Hence, the molar mass of unknown protein is 15,384.43 g/mol.

Answer:

1.60 g

Explanation:

A chemist determines by measurements that 0.0500 moles of oxygen gas, that is, O₂, participate in a chemical reaction. The molar mass of oxygen is 32.00 g/mol. We can find the mass corresponding to 0.0500 moles using the following expression.

m = n × M

where

m is the mass

n are the moles

M is the molar mass

m = n × M

m = 0.0500 mol × 32.00 g/mol

m = 1.60 g

Explanation:

Most reagent forms are going to absorb water from the air; they're called "hygroscopic".  Water presence can have a drastic impact on the experiment being performed  For fact, it increases the reagent's molecular weight, meaning that anything involving a very specific molarity (the amount of molecules in the final solution) will not function properly.

Heating will help to eliminate water, although some chemicals don't react well to heat, so it shouldn't be used for all.  A dessicated environment is simply a means to  "dry."  That allows the reagent with little water in the air to attach with.

Answer: Use of Etherificarion followed by fractional distinction.

Explanation:

It is done by reacting a mixture of tetrahydrofurfuryl alcohol and up to about one equivalent of at least one low work function element, Reacting the said mixture with a halide; fractionally distilling said reacted mixture to yield the first distillate; reacting said first distillate with an excess amount of at least one low work function element; and, fractionally distilling said reacted first distillate to obtain the purified ether wherein said at least one low work function element is an elemental metal or a metal hydride which has a φ of less than about 3.0 eV.

Answer: 25.37055324733817mol

Approximately 25.371mol

Explanation: Number of moles of a substance is the mass of that substance containing the same amount of fundamental units, for instance atom in 12.0g of 12°C

Therefore:

Number of moles= mass/ molecular mass

Where mass of fluorine given= 482g

Standard Molecular mass of fluorine= 18.9984032g/mol

Substituting value in equation

Mole= 482g/18.9984032g/mol = 25.37055324733817mol

Approximately : 25.371mol

Answer:

102 L

Explanation:

Data of the solution

The moles of HCl in the solution are:

1.25 L × 3.20 mol/L = 4.00 mol

The gas must contain 4.00 moles of HCl

Data of the gas

745 torr × (1 atm/760 torr) = 0.980 atm

We can the volume (V) of HCl gas using the ideal gas equation.

P × V = n × R × T

V = n × R × T/P

V = 4.00 mol × (0.08206 atm.L/mol.K) × 303.2 K/ 0.980 atm

V = 102 L

Answer:

0.346 M

Explanation:

Let's consider the following neutralization reaction.

NaOH + HCl → NaCl + H₂O

24.7 mL of 0.140 M NaOH react. The reacting moles are:

24.7 × 10⁻³ L × 0.140 mol/L = 3.46 × 10⁻³ mol

The molar ratio of NaOH to HCl is 1:1. The moles of HCl that reacted are 3.46 × 10⁻³ moles.

3.46 × 10⁻³ moles of HCl are contained in 10.0 mL. The molarity of HCl is:

3.46 × 10⁻³ mol/ 10.0 × 10⁻³ L = 0.346 M

Answer: c. oxygen-17

Explanation:

The isotopic representation of an atom is: [tex]_Z^A\textrm{X}[/tex]

where,

Z = Atomic number of the atom

A = Mass number of the atom

X = Symbol of the atom

In a nuclear reaction, the total mass and total atomic number remains the same.

For the given nuclear reaction:

[tex]^{14}_{7}\textrm{N}+^4_2\textrm{He}\rightarrow ^A_Z\textrm{X}+^{1}_{1}\textrm{H}[/tex]

To calculate A:

Total mass on reactant side = total mass on product side

14 + 4= A + 1

A = 17

To calculate Z:

Total atomic number on reactant side = total atomic number on product side

7+ 2 = Z + 1

Z = 8

The isotopic symbol of element is [tex]_{17}^{8}\textrm{O}[/tex]

Thus a proton is produced along with oxygen-17.

A proton is produced along with:

c. oxygen-17

[tex]^AX_Z[/tex]

where,

Z = Atomic number of the atom

A = Mass number of the atom

X = Symbol of the atom

In a nuclear reaction, the total mass and total atomic number remains the same.

For the given nuclear reaction:

[tex]^{14}N_7+^4He_2----- > ^AX_Z+^1H_1[/tex]

To calculate A:

Total mass on reactant side = total mass on product side

14 + 4= A + 1

A = 17

To calculate Z:

Total atomic number on reactant side = total atomic number on product side

7+ 2 = Z + 1

Z = 8

The isotopic symbol of element is: [tex]^8O_{17}[/tex]

Thus, A proton is produced along with oxygen-17

Find more information about Isotopic symbol here:

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