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iogann1982 [59]
3 years ago
7

Carminic acid, a naturally occurring red pigment extracted from the cochineal insect, contains only carbon, hydrogen, and oxygen

. It was commonly used as a dye in the first half of the nineteenth century. It is 53.66% C and 4.09% H by mass. A titration required 18.02 mL of 0.0406 M NaOH to neutralize 0.3602 g of carminic acid. Assuming that there is only one acidic hydrogen per molecule, what is the molecular formula of carminic acid?
Chemistry
1 answer:
lana66690 [7]3 years ago
3 0

Answer:

C₂₂H₂₀O₁₃

Explanation:

In a reaction of neutralization, an acid and a base must react to form salt and water. The ions OH⁻ of the base must react with the ions H⁺ of the acid. If there is only one hydrogen acid, it means that the number of moles of OH⁻ and H⁺ must be the same, or the number of moles of NaOH and the acid is the same.

If the concentration of NaOH is 0.0406 mol/L, to find the number of moles we need to multiply it by the volume (18.02 mL = 0.01802 L)

n = 0.0406x0.01802 = 7.32x10⁻⁴ mol

The molar mass of the carminic acid is the mass divided by the number of moles, so:

MM = 0.3602/7.32x10⁻⁴

MM = 492 g/mol

The composition is 53.66% of C, 4.09% of H and 42.25% of O, so it means that the mass corresponding of these atoms in one mol are:

C = 0.5366x492 = 264 g

H = 0.0409x492 = 20 g

O = 0.4225x492 = 208 g

Knowing the molar masses (C = 12 g/mol, H = 1 g/mol, O = 16 g/mol), the number of atoms on one mol of the acid is:

C = 264/12 = 22

H = 20/1 = 20

O = 208/16 = 13

So the molecular formula is C₂₂H₂₀O₁₃

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Go'=30.5 kJ/mol
makvit [3.9K]

Answer:

a) Keq = 4.5x10^-6

b) [oxaloacetate] = 9x10^-9 M

c) 23 oxaloacetate molecules

Explanation:

a) In the standard state we have to:

ΔGo = -R*T*ln(Keq) (eq.1)

ΔGo = 30.5 kJ/moles = 30500 J/moles

R = 8.314 J*K^-1*moles^-1

Clearing Keq:

Keq = e^(ΔGo/-R*T) = e^(30500/(-8.314*298)) = 4.5x10^-6

b) Keq = ([oxaloacetate]*[NADH])/([L-malate]*[NAD+])

4.5x10^-6 = ([oxaloacetate]/(0.20*10)

Clearing [oxaloacetate]:

[oxaloacetate] = 9x10^-9 M

c) the radius of the mitochondria is equal to:

r = 10^-5 dm

The volume of the mitochondria is:

V = (4/3)*pi*r^3 = (4/3)*pi*(10^-15)^3 = 4.18x10^-42 L

1 L of mitochondria contains 9x10^-9 M of oxaloacetate

Thus, 4.18x10^-42 L of mitochondria contains:

molecules of oxaloacetate = 4.18x10^-42 * 9x10^-9 * 6.023x10^23 = 2.27x10^-26 = 23 oxaloacetate molecules

3 0
4 years ago
What is the most metallic item on the pterotic table
statuscvo [17]

Answer:

francium or cesium

7 0
3 years ago
Read 2 more answers
Calculate the density of a liquid if 58.9 ml of it has a mass of 46.08 g. answer in units of g/ml.
alexira [117]
Density of a solution is mass of solution per unit volume
Density = mass/volume
mass of solution is 46.08 g
volume of solution is 58.9 mL 
since mass and volume is known, density can be calculated
density = 46.08 g / 58.9 mL = 0.78 g/mL 
8 0
3 years ago
Does somebody know the answer ?
Alex777 [14]
H2O is the missing reactant.

Just a caveat: this equation isn’t balanced.
3 0
3 years ago
I really need help. Please
Oliga [24]

physical change

particles retain there composition and identity

there is no change in there chemical properties of the substance

the chemical changes should be the other two.

If it is wrong I'm truly sorry.

6 0
3 years ago
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