An isotonic solution contains 0.86% by mass per volume. Calculate the percent mass per volume for an isotonic solution of KCl at 30 degrees C. Assume a van't Hoff factor of 1.9.
Just figured this out for my Chemistry class.
.86 / (23 + 34.45) = X / (39 + 34.45)
Solve for X
( .86 / (23 + 34.45) ) * (39 + 34.45)
1.099 = X
X =
mark, what does the 23 represent?
23 stands for the GFM of sodium
To calculate the percent mass per volume for an isotonic solution of KCl at 30 degrees C, we need to consider the definition of an isotonic solution and use the given information.
1. Definition of an isotonic solution:
An isotonic solution is a solution that has the same concentration of solutes as a reference solution. In the case of biological systems, an isotonic solution has the same osmolarity as the fluid in the cells or the extracellular fluid.
2. Given information:
- The isotonic solution mentioned contains 0.86% by mass per volume.
- We are trying to calculate the percent mass per volume for an isotonic solution of KCl at 30 degrees C.
- The van't Hoff factor for KCl is given as 1.9.
To calculate the percent mass per volume for the KCl solution, we can use the following steps:
Step 1: Calculate the molarity of the isotonic solution.
- The given 0.86% by mass per volume corresponds to 0.86 grams of solute (KCl) per 100 mL of solution.
- To convert from mass per volume to molarity, we need to know the molar mass of KCl, which is 74.55 g/mol.
- Calculate the number of moles of KCl:
Moles = Mass / Molar mass
Moles = 0.86 g / 74.55 g/mol
- Convert to the molarity by dividing by the volume in liters:
Molarity = Moles / Volume (in L)
Volume (in L) = 100 mL / 1000 (conversion from mL to L)
Molarity = Moles / Volume (in L)
Step 2: Calculate the concentration in terms of percent mass per volume:
- To determine the percent mass per volume, we need to convert the molar concentration (M) to mass per volume (% w/v).
- Calculate the mass of KCl in grams:
Mass (g) = Molarity (mol/L) * Molar mass (g/mol) * Volume (L)
- Calculate the percent mass per volume:
% w/v = (Mass (g) / Volume (mL)) * 100
Step 3: Adjust the concentration to consider the van't Hoff factor:
- The van't Hoff factor accounts for the number of particles the solute ionizes into in the solution.
- In this case, the van't Hoff factor for KCl is given as 1.9.
- Multiply the percent mass per volume by the van't Hoff factor to adjust for the ionization:
Adjusted % w/v = % w/v * van't Hoff factor
By following these steps, we can calculate the percent mass per volume for the isotonic solution of KCl at 30 degrees C.