A person’s blood alcohol (C2H5OH) level can be determined by titrating a sample of blood plasma with a potassium dichromate solution. The balance is

16H+ (aq) + 2Cr2O72- (aq) + C2H5OH (aq) 4Cr3+ (aq) + 2CO2 (g) + 11H2O (l)

If 35.46 mL of 0.05961 M Cr2O72- is required to titrate 30.50 g of plasma, What is the mass percent of alcohol in the blood?

__________ mass %

40 mL mass % Alcohol in blood = mass alcohol/ mass blood
0.06 M

mols Cr2O7^2- = M x L = ?

Convert to mols C2H5OH by
?mols Cr2O7^2- x (1 mol C2H5OH/2 mol Cr2O6^2-) = ?mols Cr2O7^2- x 1/2 = ?
Then grams ethanol = mols ethanol x molar mass ethanol
%w/w = (mass ethanol/mass sample)*100 = ?
mass ethanol from above.
mass sample is 30.50 g from the problem.

To find the mass percent of alcohol in the blood, we need to calculate the mass of alcohol and the mass of blood.

Let's start by calculating the moles of potassium dichromate (Cr2O7^2-) used in the titration from the given volume and concentration.

moles of Cr2O7^2- = volume (L) x concentration (mol/L)
moles of Cr2O7^2- = 0.03546 L x 0.05961 mol/L

Next, we need to find the moles of alcohol (C2H5OH) from the balanced chemical equation.

According to the balanced equation:
2 moles of Cr2O7^2- reacts with 1 mole of C2H5OH.

Therefore, moles of C2H5OH = (moles of Cr2O7^2-) / 2

Now, let's calculate the mass of alcohol using its molar mass.

mass of alcohol (C2H5OH) = moles of C2H5OH x molar mass of C2H5OH

The molar mass of C2H5OH is:
2 x (Carbon's atomic mass) + 6 x (Hydrogen's atomic mass) + (Oxygen's atomic mass)

Finally, we can calculate the mass percent of alcohol using the following formula:

mass percent = (mass of alcohol / mass of blood) x 100

By substituting the calculated values into the formula, we can find the mass percent of alcohol in the blood.

To find the mass percent of alcohol in the blood, we need to calculate the mass of alcohol in the blood and the mass of the blood itself.

Given information:
Volume of Cr2O72- solution = 35.46 mL
Concentration of Cr2O72- solution = 0.05961 M
Mass of plasma = 30.50 g

Now let's calculate the moles of Cr2O72- used in the titration:

Moles of Cr2O72- = Concentration × Volume
Moles of Cr2O72- = 0.05961 M × (35.46 mL / 1000 mL/L) (converting mL to L)
Moles of Cr2O72- = 0.00211724406 mol

From the balanced chemical equation, we can see that the mole ratio between C2H5OH (alcohol) and Cr2O72- is 1:2. That means for every 2 moles of Cr2O72- used, we have 1 mole of alcohol (C2H5OH).

So, moles of C2H5OH = 0.00211724406 mol / 2 = 0.00105862203 mol

To calculate the mass of alcohol, we can use the molar mass of C2H5OH:

Molar mass of C2H5OH = (2 × Atomic mass of C) + (6 × Atomic mass of H) + Atomic mass of O
Molar mass of C2H5OH = (2 × 12.01 g/mol) + (6 × 1.01 g/mol) + 16.00 g/mol
Molar mass of C2H5OH = 46.07 g/mol

Mass of alcohol = moles of C2H5OH × molar mass of C2H5OH
Mass of alcohol = 0.00105862203 mol × 46.07 g/mol
Mass of alcohol = 0.0488501893 g

To calculate the mass percent of alcohol in the blood, we need to divide the mass of alcohol by the mass of the blood and multiply by 100:

Mass percent of alcohol = (Mass of alcohol / Mass of blood) × 100
Mass percent of alcohol = (0.0488501893 g / 30.50 g) × 100
Mass percent of alcohol = 0.16%

Therefore, the mass percent of alcohol in the blood is approximately 0.16%.