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3 years ago

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156 g C12H22O11 (sucrose) is dissolved into 4.0 L of solution. What is the molar concentration of the solution? Report your answ

er with the correct number of significant figures.

1 answer:

saveliy_v [14]3 years ago

3 0

Answer:

The molar concentration is 0.114 M (≈0.11 M)

Explanation:

Step 1: Data given

Mass of sucrose = 156 grams

Molar mass of sucrose = 342.3 g/mol

Volume = 4.0 L

Step 2: Calculate moles sucrose

Moles sucrose = mass sucrose / molar mass sucrose

Moles sucrose = 156 grams / 342.3 g/mol

Moles sucrose = 0.456 moles

Step 3: Calculate molar concentration of the solution

Concentration of solution = moles sucrose / volume

Concentration of solution = 0.456 moles / 4.0 L

Concentration of solution = 0.114 M

The molar concentration is 0.114 M (≈0.11 M)

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A chemist dissolves 867. mg of pure barium hydroxide in enough water to make up 170. mL of solution. Calculate the pH of the sol

Ilya [14]

Answer: The pH of the solution is 11.2

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n = moles of solute

$V_s$ = volume of solution in ml

moles of $Ba(OH)_2$ = $\frac{\text {given mass}}{\text {Molar mass}}=\frac{0.867g}{171g/mol}=0.00507mol$ (1g=1000mg)

Now put all the given values in the formula of molality, we get

$Molarity=\frac{0.00507\times 1000}{170}$

$Molarity=0.0298$

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

$pOH=-\log [OH^-]$

$Ba(OH)_2\rightarrow Ba^{2+}+2OH^{-}$

According to stoichiometry,

1 mole of $Ba(OH)_2$ gives 2 mole of $OH^-$

Thus 0.0298 moles of $Ba(OH)_2$ gives = $\frac{2}{1}\times 0.0298=0.0596$ moles of $OH^-$

Putting in the values:

$pOH=-\log[0.0596]=2.82$

$pH+pOH=14$

$pH=14-2.82$

$pH=11.2$

Thus the pH of the solution is 11.2

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3 years ago

In the absence of sodium methoxide, the same alkyl bromide gives a different product. Draw an arrowpushing mechanism to account

hoa [83]

Answer:

See explanation below

Explanation:

The question is incomplete, cause you are not providing the structure. However, I found the question and it's attached in picture 1.

Now, according to this reaction and the product given, we can see that we have sustitution reaction. In the absence of sodium methoxide, the reaction it's no longer in basic medium, so the sustitution reaction that it's promoted here it's not an Sn2 reaction as part a), but instead a Sn1 reaction, and in this we can have the presence of carbocation. What happen here then?, well, the bromine leaves the molecule leaving a secondary carbocation there, but the neighbour carbon (The one in the cycle) has a more stable carbocation, so one atom of hydrogen from that carbon migrates to the carbon with the carbocation to stabilize that carbon, and the result is a tertiary carbocation. When this happens, the methanol can easily go there and form the product.

For question 6a, as it was stated before, the mechanism in that reaction is a Sn2, however, we can have conditions for an E2 reaction and form an alkene. This can be done, cause the extoxide can substract the atoms of hydrogens from either the carbon of the cycle or the terminal methyl of the molecule and will form two different products of elimination. The product formed in greater quantities will be the one where the negative charge is more stable, in this case, in the primary carbon of the methyl it's more stable there, so product 1 will be formed more (See picture 2)

For question 6b, same principle of 6a, when the hydrogen migrates to the 2nd carbocation to form a tertiary carbocation the methanol will promove an E1 reaction with the vecinal carbons and form two eliminations products. See picture 2 for mechanism of reaction.

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3 years ago

T or F: The mass of an answer is so small it is rounded to 0 amu

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True because it doesn’t count as a full number

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3 years ago

A city's water supply is contaminated with a toxin at a concentration of 0.63 mg/L. For the water to be safe for drinking, the c

Shalnov [3]

Answer:

Approximately 22.37 days, will it take for the water to be safe to drink.

Explanation:

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

Where,

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

k is rate constant

Given that:- k = 0.27 (day)⁻¹

$[A_0]$ = 0.63 mg/L

$[A_t]=1.5\times 10^{-3}$ mg/L

Applying in the above equation as:-

$1.5\times 10^{-3}=0.63e^{-0.27\times t}$

$63e^{-0.27t}=150\times \:10^{-3}$

$e^{-0.27t}=\frac{1}{420}$

$t=\frac{100\ln \left(420\right)}{27}=22.37$

<u>Approximately 22.37 days, will it take for the water to be safe to drink.</u>

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Describe the atomic theory of atoms

alexandr402 [8]

Answer: Below

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Explanation:

The atomic theory is that all matter is made up of tiny units or particles called atoms. This theory describes the characteristics, structure and behavior of atoms as well as the components that make up atoms. Furthermore, the theory states that all elements are made up of identical atoms.

The atomic theory is a theory in the study of chemistry that states atoms are the building blocks of matter. Atoms contain protons, neutrons and electrons. Protons, which have a positive charge, and neutrons are found in the nucleus of the atom. Electrons, which have a negative charge, orbit the nucleus.

According to the atomic theory, all elements contain atoms. The difference is the number of protons, electrons and neutrons in that atom. For instance, hydrogen contains one proton and one electron but no neutrons. Oxygen, on the other hand contains eight protons, electrons and neutrons. The difference in protons, electrons and neutrons determines the stability and the other properties of any particular element. These elements are grouped according to their atomic masses, which depend on the number of protons and neutrons in each of the atoms. Because oxygen has more protons and neutrons than hydrogen, it has a higher atomic mass.

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3 years ago