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Taya2010 [7]
3 years ago
9

The active ingredient in aspirin is acetylsalicylic acid. A 2.79 g sample of acetylsalicylic acid required 30.15 mL of 0.5137 M

NaOH for complete reaction. Addition of 17.41 mL of 0.4448 M HCl to the flask containing the aspirin and the sodium hydroxide produced a mixture with pH = 3.48. Find the molar mass in g/mol) of acetylsalicylic acid and its K, value. Acetylsalicylic acid is a monoprotic acid. molar mass 49 g/mol Ka
Chemistry
1 answer:
vivado [14]3 years ago
5 0

Answer:

Molar mass = 180 g/mol

Ka = 3.31x10⁻⁴

Explanation:

Because the acetylsalicylic is a monoprotic acid, it only leaves 1 mol of H⁺ in the reaction, so, it's necessary 1 mol of NaOH for each 1 mol of acetylsalicylic acid. The number of moles of NaOH is the volume, in L, multiplied by the concentration:

n = 0.03015*0.5137 = 0.01549

Which is also the number of moles of the acid. The molar mass is the mass, in g, divided by the number of moles:

M = 2.79/0.01549

M = 180 g/mol

After reacting with the base, the conjugate base of the acid will be formed, and the equilibrium between the acid form (HA) and the conjugate base (A⁻) is a buffer. It formed 0.01549 moles of A⁻, which will react with the moles of H⁺ from HCl to form HA.

nH⁺ = nHCl = 0.01741*0.448 = 0.0078 mol

A⁻           +       H⁺            ⇄   HA

0.01549     0.0078                 0        Initial

-0.0078     -0.0078         +0.0078   Reacts

0.0078            0                0.0078   Equilibrium

For a buffer, the pH can be calculated by the Handerson-Halsebach equation:

pH = pKa + log[A⁻]/[HA]

Because the volume is the same, we can use the number of moles instead of the concentration:

3.48 = pKa + log(0.0078/0.0078)

pKa = 3.48

pKa = -logKa

Ka = 10^{-pKa}

Ka = 10^{-3.48}

Ka = 3.31x10⁻⁴

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How many moles of sodium ions are present in 0.25 kg of a 2.0 m solution of sodium chloride in water
LenKa [72]

0.50 is the answer on edge

8 0
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g Stereoisomers that are not mirror images of each are ____________ . The cis and trans isomers of a particular compound are ___
mel-nik [20]

Answer:

Diasteriomers

Stereoisomers

Stereoisomers

Meso compounds

Constitutional isomers

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Enantiomers

Explanation:

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Constitutional isomers differ only in atom to atom connectivity while stereoisomers differ in arrangement of atoms in space. Stereo isomers differ in physical and chemical properties of the compounds.

When stereo isomers are non-superimpossible mirror images of each other, they are called enantiomers. Enantiomers have the same chemical and physical properties and differ only in their reaction with chiral substances.

Achiral compounds are compounds that do not exhibit chirality. Some achiral compounds contain stereogenic centers and are called meso compounds.

8 0
3 years ago
Starting with 2.50 mol of N2 gas (assumed to be ideal) in a cylinder at 1.00 atm and 20.0C, a chemist first heats the gas at con
arsen [322]

Answer:

a)  T_b=590.775k

b)  W_t=1.08*10^4J

d)  Q=3.778*10^4J

d)  \triangle V=4.058*10^4J

Explanation:

From the question we are told that:

Moles of N2 n=2.50

Atmospheric pressure P=100atm

Temperature t=20 \textdegree C

                      t = 20+273

                     t = 293k

Initial heat Q=1.36 * 10^4 J

a)

Generally the equation for change in temperature is mathematically given by

\triangle T=\frac{Q}{N*C_v}

  Where

  C_v=Heat\ Capacity \approx 20.76 J/mol/K

T_b-T_a=\frac{1.36 * 10^4 J}{2.5*20.76 }

T_b-293k=297.775

T_b=590.775k

b)

Generally the equation for ideal gas is mathematically given by

 PV=nRT

For v double

 T_c=2*590.775k

 T_c=1181.55k

Therefore

PV=Wbc

Wbc=(2.20)(8.314)(1181_590.778)

Wbc=10805.7J

Total Work-done W_t

W_t=Wab+Wbc

W_t=0+1.08*10^4

W_t=1.08*10^4J

c)

Generally the equation for amount of heat added is mathematically given by

Q=nC_p\triangle T

Q=2.20*2907*(1181.55-590.775)\\

Q=3.778*10^4J

d)

Generally the equation for change in internal energy of the gas is mathematically given by

\triangle V=nC_v \triangle T

\triangle V=2.20*20.76*(1181.55-293)k

\triangle V=4.058*10^4J

3 0
2 years ago
A box of jello has a mass of 250 g. How many boxes must be bought to have 1 Kg of jello? *
zhuklara [117]

Answer:

Number of boxes = 4

Explanation:

Given:

Mass of one box of jello = 250 grams

Total quantity want to purchase = 1 kg = 1 × 1,000 gram = 1,000 grams

Find:

Number of boxes in 1,000 grams = ?

Computation:

Number of boxes = Total quantity want to purchase / Mass of one box of jello

Number of boxes = 1,000 / 250

Number of boxes = 4

Therefore, 4 boxes of jello must be purchase to get 1 kg of Jello.

8 0
3 years ago
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