The pH of arterial blood is 7.42. When 10 mL of the blood is acidified, 5.91 mL of CO2 is produced.
1) what is the total concentration of CO2 in the blood [CO2]+[HCO3-]? The experimental value for the volume of one mole of CO2 is 22.26 L/mol.
2) What are the individual concentrations of CO2 and HCO3-?
I have no idea what the first question is asking.
Thanks in advance!
Can't you determine the moles CO2 by 5.91 mL (change to L)/22.26 L/mol = ??
Then substitute into the Henderson-Hasselbach equation
pH = pKa + log (HCO3^-)/(CO2)
and solve for (HCO3^-). Change to mols HCO3^-, add moles CO2 (present as H2CO3), then divide moles/L to find total concn?
The answer to the second problem you obtained to get the answer for the first part. I think pKa is 6.1 or close to that.
Thanks for this
Please how do you change hco3 concentration to mole not given volume??
To answer the first question, we need to consider the reaction between CO2 and H2O which gives rise to carbonic acid (H2CO3). Carbonic acid can then dissociate into H+ and HCO3- ions. This reaction can be represented as:
CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-
Since the reaction is in equilibrium, we can use the Henderson-Hasselbalch equation to calculate the ratio between HCO3- and CO2. The Henderson-Hasselbalch equation is:
pH = pKa + log([HCO3-] / [CO2])
Given that the pH of arterial blood is 7.42, we can rearrange the equation to solve for [HCO3-] / [CO2]:
[HCO3-] / [CO2] = 10^(pH - pKa)
The pKa for the H2CO3/HCO3- equilibrium is around 6.1 to 6.3, so let's assume a pKa value of 6.2 for our calculation.
[HCO3-] / [CO2] = 10^(7.42 - 6.2)
[HCO3-] / [CO2] = 10^1.22
[HCO3-] / [CO2] ≈ 15.8
Since we know that the volume of one mole of CO2 is 22.26 L/mol, we can assume that the volume of CO2 produced (5.91 mL) corresponds to its molar concentration.
[CO2] = (5.91 mL) / (22.26 L/mol)
[CO2] ≈ 0.265 mol/L
Now, we can find the concentration of HCO3-:
[HCO3-] = [CO2] / [HCO3-] / [CO2]
[HCO3-] ≈ (0.265 mol/L) / 15.8
[HCO3-] ≈ 0.0168 mol/L
To calculate the total concentration of CO2 in the blood ([CO2]+[HCO3-]), we simply add the individual concentrations together:
[CO2]+[HCO3-] ≈ (0.265 mol/L) + (0.0168 mol/L)
[CO2]+[HCO3-] ≈ 0.2828 mol/L
Therefore, the total concentration of CO2 in the blood is approximately 0.2828 mol/L.
Now let's move on to the second question.
The individual concentrations of CO2 and HCO3- are:
[CO2] ≈ 0.265 mol/L
[HCO3-] ≈ 0.0168 mol/L
No problem! Let's break down the questions step by step.
1) What is the total concentration of CO2 in the blood [CO2]+[HCO3-]?
To find the total concentration of CO2 in the blood, we need to calculate the amount of CO2 produced when 10 mL of blood is acidified.
Given: Volume of one mole of CO2 = 22.26 L/mol
Volume of CO2 produced = 5.91 mL
First, let's convert the volume of CO2 produced from milliliters to liters:
5.91 mL = 5.91 * 10^(-3) L (since there are 1000 mL in 1 L)
Next, we need to find the number of moles of CO2 produced. We can use the following equation to relate volume and moles when the pressure and temperature are constant:
n = V / Vm
Where:
n = number of moles
V = volume of gas
Vm = molar volume of gas
Plugging in our values:
n = (5.91 * 10^(-3) L) / (22.26 L/mol) = 0.000265 mol
Now, since we assumed that all the CO2 produced came from the reaction of HCO3- in the blood, the total concentration of CO2 and HCO3- remains constant. Therefore, the total concentration of CO2 ([CO2]+[HCO3-]) would be 0.000265 mol.
2) What are the individual concentrations of CO2 and HCO3-?
Since the total concentration of CO2 and HCO3- remains constant and we calculated the total concentration to be 0.000265 mol in the previous question, both the individual concentrations of CO2 and HCO3- would be 0.000265 mol.
So, both the individual concentrations of CO2 and HCO3- are 0.000265 mol.
Remember, when answering these types of questions, it's important to pay attention to the given information, convert units if necessary, and use appropriate formulas or equations to arrive at the correct answers.