PRACTICE PROBLEM Two compounds, A and B, have the same molecular formula, C6H8. Both A and B react with two molar equivalents of hydrogen in the presence of platinum to yield cyclohexane. Compound A shows three signals in its broadband decoupled NMR spectrum. Compound B shows only two NMR signals. Compound A shows an absorption maximum at 256 nm, whereas B shows no absorption maximum at wavelengths longer than 200 nm. What are the structures of A and B

Answer: The atomic mass of silver is 107.8

Explanation:

Average atomic mass is the average mass of all the isotopes present depending on the relative abundance of each isotope.

Mass of isotope A = 106.9051

% abundance of isotope 1 = 51.82% = [tex]\frac{51.82}{100}[/tex]

Mass of isotope B = 108.9047

% abundance of isotope 2 = (100-51.82)% = [tex]\frac{48.18}{100}[/tex]

Formula used for average atomic mass of an element :

[tex]A=\sum[(106.9051)\times \frac{51.82}{100})+(108.9047)\times \frac{48.18}{100}]][/tex]

[tex]A=107.8[/tex]

Therefore, the average atomic mass of silver is 107.8

Answer:

Changes in environment, food source changes and disease?

Explanation:

I dont know what the answer choices are

Answer:

changes in the environment

Explanation:

like digging big holes.

Hope this helps!

Moles of [tex]H_2O[/tex] ,

[tex]n_{H_2O}=\dfrac{42}{2\times 1 + 16}=\dfrac{42}{18}\\\\n_{H_2O}=2.33\ moles[/tex]

Moles of acetic acid [tex]HCH_3CO_2[/tex] ,

[tex]n_{A.A}=\dfrac{77}{1 + 12 + 3 + 12 + 16\times 2}=\dfrac{77}{60}\\\\n_{A.A}=1.28\ moles[/tex]

Mole fraction of water :

[tex]M.F_{H_2O}=\dfrac{n_{H_2O}}{n_{H_2O}+n_{A.A}}\\\\M.F_{H_2O}=\dfrac{2.33}{2.33+1.28}\\\\M.F_{H_2O}=0.645[/tex]

Therefore, mole fraction of water in this solution is 0.645 .

Hence, this is the required solution.

Answer:

4.5 × 10⁻⁹

Explanation:

Step 1: Write the reaction for the solution of CaCO₃

CaCO₃(s) ⇄ Ca²⁺(aq) + CO₃²⁻(aq)

Step 2: Convert the solubility of CaCO₃ from g/L to mol/L

We will use the following conversion factors:

[tex]\frac{0.00067 gCaCO_3}{100mLSol} \times \frac{1molCaCO_3}{100.09gCaCO_3} \times \frac{1000mLSol}{1LSol} = 6.7 \times 10^{-5} M[/tex]

Step 3: Calculate the solubility product constant (Ksp)

To relate Ksp and the molar solubility (S), we need to make an ICE chart.

        CaCO₃(s) ⇄ Ca²⁺(aq) + CO₃²⁻(aq)

I                               0                0

C                            +S               +S

E                              S                 S

The solubility product constant is:

Ksp = [Ca²⁺].[CO₃²⁻] = S² = (6.7 × 10⁻⁵)² = 4.5 × 10⁻⁹

Answer:

8,903.09 square meters

Explanation:

Doing a quick search online we can see that there are exactly 4046.86 square meters in a single acre (1 acre). Therefore, we can simply use the rule of three to calculate the total amount of square meters in 2.2 acres. We do this by multiplying 2.2 acres by 4046.86 square meters and then dividing by 1 acre to solve for x.

1 acre  <=====>  4046.86 square meters

2.2 acres <====> x

(2.2 * 4046.86) / 1 = x

8903.09 / 1 = x

8,903.09 = x

Finally, we can see that there are 8,903.09 square meters in 2.2 acres.

Answer:

[H+] = 7.576x10⁻⁴M

pH = 3.12

Explanation:

Based on the equilibrium of the nicotinic acid in water:

HC6H4NO2(aq) + H2O(l) ⇄ C6H4NO2-(aq) + H3O+(aq)

Ka = [C6H4NO2-] [H3O+] / [HC6H4NO2]

As both C6H4NO2-(aq) and H3O+(aq) comes from the same equilibrium, we can approximate their concentration as X and replace:

Ka = [C6H4NO2-] [H3O+] / [HC6H4NO2]

1.4x10⁻⁵ = [X] [X] / [0.041M]

5.47x10⁻⁷ = X²

And as pH is defined as -log [H⁺]

Answer:

Endothermic reaction

Explanation:

Endothermic reactions are defined as the type of chemical reaction in which the system absorbs the energy from the surroundings and the temperature of the surrounding decreases while in Exothermic reactions, heat is released by the system to the surroundings and it makes the surrounding warm.

The given example is an "endothermic reaction" because the reaction between NH4Cl and water is making the surrounding cool (cold pack) due to the release of heat.

Hence, the correct answer is "endothermic reaction".

Answer:

See explanation

Explanation:

a) -About 1-2 drops of the unknown is dissolved in approximately 1 mL of analytical grade acetone standard solution. The test solution is added and shaken thoroughly.  If a positive test is not immediately observed, the set should be allowed to stand for 1-2 minutes. A positive result means the appearance of a green color.

b) The functional groups that can be distinguished by the test are alcohols and aldehydes.

Aldehydes give a positive test to chromic acid but ketones do not.

Primary and secondary alcohols give a positive test to chromic acid but tertiary alcohols do not.

c) Chromic Acid Test involves Cr in the +6 oxidation state. A positive test implies the reduction of orange Cr^6+ to green chromium Cr^3+.

d) The compounds were not shown but this image attached from lumen learning summarizes the reaction mechanism of chromic acid test.

Answer:

100 joules​

Explanation:

The mechanical energy (M.E) of an object describes the objects ability to do work. The mechanical energy encompasses the object's energy due to its position (potential energy) and its energy due to motion (kinetic energy).

Therefore,

M.E = K.E + P.E

According to this question, potential energy (P.E) of the roller coaster is 50J and the kinetic energy (K.E) is also 50J. Hence, the mechanical energy (M.E) is

M.E = 50J + 50J

M.E = 100J

If the P.E and K.E of a roller coaster is 50 Joules respectively, the mechanical energy of the roller coaster is 100 Joules.

Given the following data:

To find the mechanical energy of the roller coaster:

The mechanical energy of a physical object or body is the total sum of the potential energy (P.E) and kinetic energy (K.E) possessed by an object.

Mathematically, mechanical energy is given by the formula;

Substituting the given parameters into the formula, we have;

[tex]M.E = 50 + 50[/tex]

Mechanical energy (M.E) = 100 Joules.

Therefore, the mechanical energy of the roller coaster is 100 Joules.

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Answer:

True

Explanation:

But have different neutrons

Answer:

organ system

Explanation:

Answer:

B) organ

Explanation:

Answer:

[tex]0.326\frac{N}{cm^2}[/tex]

Explanation:

Hello.

In this case, considering that 1 atm equals 1.01 kPa, we can compute the pressure in kPa first as shown below:

[tex]2.25atm*\frac{1.01kPa}{1atm} =3.26kPa[/tex]

Now, we convert kPa to Pa, considering 1 kPa equals 1000 Pa:

[tex]3.26kPa*\frac{1000Pa}{1kPa}=3260Pa[/tex]

Now, since Pa is equal to N/m², and 1 m equals 100 cm, the pressure in newton per square centimeter turns out:

[tex]3260\frac{N}{m^2}*(\frac{1m}{100cm})^2 \\\\0.326\frac{N}{cm^2}[/tex]

Best regards.

Answer:

Explanation:

Since the student fills up the buret with NaOH without rinsing it with small amount of NaOH , the water that is remaining stuck with the walls of the buret will dilute the solution of NaOH and it will result in lowering the morality of the solution . The molar concentration of the NaOH will no longer remain the same . It will lead to wrong calculation and hence wrong result.

The washing of burette in titration with NaOH solution results in the maintaining the concentration of the NaOH in the solution and allows the correct calculation of the molarity.

The titration has been the reaction of the acid with the base resulted in the formation of salt and water and had the neutralization reaction.

The molarity of the base has been used in the analysis of the acid concentration on the neutralization reaction.

The skipping of the step of washing with NaOH resulted in the altering in the concentration of the NaOH with the stuck water on the walls of the burette, and thereby resulted in wrong calculation.

Learn more about titration, here:

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Answer:

make an observation that describes a problem

Explanation:

Answer:

The first step in the Scientific Method is to make objective observations.

Explanation:

....-

Answer:

I literally got this from google.

Explanation:

In ordinary air, sodium metal reacts to form a sodium hydroxide film, which can rapidly absorb carbon dioxide from the air, forming sodium bicarbonate. ... In a comparatively dry atmosphere, sodium burns quietly, giving off a dense white caustic smoke, which can cause choking and coughing.

Happy almost Halloween! :)

Answer:

3.13%.

Explanation:

The following data were obtained from the question:

Original amount (N₀) = 0.15

Half life (t½) = 2 mins

Number of half-life (n) = 5

Fraction of sample remaining =.?

Next, we shall determine the amount remaining (N) after 5 half-life. This can be obtained as follow:

Amount remaining (N) = 1/2ⁿ × original amount (N₀)

NOTE: n is the number of half-life.

N = 1/2ⁿ × N₀

N = 1/2⁵ × 0.15

N = 1/32 × 0.15

N = 0.15/32

N = 4.69×10¯³

Therefore, 4.69×10¯³ is remaining after 5 half-life.

Finally, we shall the fraction of the sample remaining after 5 half-life as follow:

Original amount (N₀) = 0.15

Amount remaining (N) = 4.69×10¯³

Fraction remaining = N/N₀ × 100

Fraction remaining = 4.69×10¯³/0.15 × 100

Fraction remaining = 3.13%

Answer:

ARSENIC

Explanation:

It has an atomic number of 33

Answer:1

Explanation:i know cuz I got it right

NaBr is classified as a compound because sodium and bromine are chemically combined in a fixed proportion.

Explanation:

So, from this, we can conclude that NaBr is classified as a compound because sodium and bromine are chemically combined in a fixed proportion.

Learn more about elements and compounds here:

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Answer:

C.

Explanation:

You can use the series of elimination for this. First, you look at A. Technology is not an understanding of something new, so we cross that out. Second, you look at B. Technology isn't a series of steps, so we can mark that one off. Third, you look at C. Technology is something created using science for use by society, so we can keep that in mind. Lastly, we check D. Technology doesn't match up to the definition, so we can cross that one out. The answer that would make the most sense would be D.

Answer:

1) 97.6%

2) No the purity is not acceptable because the standard is 99.5% purity.

3) Yes I will repeat the titration experiment to confirm my result.

Explanation:

Equation of the reaction;

C7H6O2(aq) + NaOH(aq) ---------> C7H5ONa(aq) + H2O(aq)

From the information provided;

Number of moles of NaOH reacted = concentration × volume = 20.15/1000 × 0.500 = 0.01 moles

From the reaction equation;

1 mole of C7H6O2 reacts with 1 mole of NaOH

Hence 0.01 moles of C7H6O2 will react with 0.01 moles of NaOH

Mass of C7H6O2 reacted = number of moles of C7H6O2 × molar mass of C7H6O2

Molar mass of C7H6O2 = 122.12 g/mol

Mass of C7H6O2 reacted = 0.01 moles × 122.12 g/mol = 1.22 g

Percentage by mass of pure C7H6O2 in the impure sample = 1.22/1.250 × 100 = 97.6 %

Answer:

Organic

Explanation:

Edge student

Answer:

3

Explanation:

I wish you the best, its three or 2

Answer:

2

Explanation:

Edge 2021

Answer:..

Explanation:

Answer:

1.14 M

Explanation:

Let's consider the following reaction.

butane ⇄ isobutane

We can use the concentrations at equilibrium to calculate the equilibrium constant.

Kc = [isobutane] / [butane]

Kc = 2.5 / 1.0

Kc = 2.5

If we add 0.50 M of isobutane, we get [isobutane] = 2.5 + 0.50 = 3.0 M.

This will be an initial concentration in an ICE chart.

        butane ⇄ isobutane

I           1.0              3.0

C         +x                -x

E        1.0+x           3.0-x

The equilibrium constant is:

Kc = 2.5 = [isobutane] / [butane]

2.5 = (3.0-x) / (1.0+x)

2.5 + 2.5x = 3.0-x

x = 0.14

The equilibrium concentration of butane is:

[butane] = 1.0+x = 1.14 M

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