Question

A chemist prepares a solution of barium chloride by measuring out of barium chloride into a volumetric flask and filling the flask to the mark with water.Calculate the concentration in μmol L of the chemist's barium chloride solution. Round your answer to 2 significant digits.

Answer 1

The concentration of the barium chloride solution in μmol/L can be calculated by converting the mass of BaCl2 to moles, dividing by the solution volume in liters, and then multiplying by 106 to get the concentration in μmol/L, rounding the final answer to two significant digits.

Step-by-step explanation:

To calculate the concentration of a chemist's barium chloride solution in μmol/L, we must utilize the formula for molarity, which is the number of moles of solute per liter of solution. In this scenario, we are missing the actual mass of barium chloride used by the chemist; let's assume it's 'x' grams. Once the mass is known, it is converted to moles using the molar mass of barium chloride (BaCl2), which is 208.23 g/mol.

After finding the moles, the solution's volume must be accounted for. If the volumetric flask is filled to the mark with water, the final volume will be 1.00 L unless a different volume is specified. The molar concentration is the moles of BaCl2 divided by this volume. To convert molarity to μmol/L, multiply by 106.

Here is an example calculation:

1. 
   
2. Convert mass ('x' grams) of BaCl2 to moles: Moles = Mass / Molar Mass.
3. 
   
4. Calculate molarity (μM): Molarity = Moles / Volume (L).
5. 
   
6. Convert molarity to μmol/L by multiplying by 106.

The final answer should be rounded to two significant digits, reflecting appropriate significant figures based on the measurement precision stated in the question.

Answer 2

30 μmol/L

Step-by-step explanation:

A chemist prepares a solution of barium chloride by measuring out 8.9 μmol of barium chloride into a 300mL volumetric flask and filling the flask to the mark with water.

Calculate the concentration in μmol L of the chemist's barium chloride solution. Round your answer to 2 significant digits.

The chemist has 8.9 μmol of solute (barium chloride) and he adds water until the mark of 300 mL in the container, which is the volume of the solution. We will need the conversion factor 1 L = 1000 mL. The concentration of barium chloride in μmol/L is:

`(8.9\mu mol)/(300mL) .(1000mL)/(1L) =30\mu mol/L`