We wish to determine the mass of [tex]BaSO_4[/tex] formed when [tex]200 \, \text{mL}[/tex] of [tex]0.10 \, \text{M} \, BaCl_2[/tex] reacts with excess [tex]Na_2SO_4[/tex] according to the equation below:

[tex]\[ BaCl_2(aq) + Na_2SO_4(aq) \rightarrow BaSO_4(s) + 2NaCl(aq) \][/tex]

How many moles of [tex]BaCl_2[/tex] are present in [tex]200 \, \text{mL}[/tex] of [tex]0.10 \, \text{M} \, BaCl_2[/tex]?



Answer :

Let's break down the problem step-by-step to find the number of moles of [tex]\( \text{BaCl}_2 \)[/tex] present in 200 mL of a 0.10 M [tex]\( \text{BaCl}_2 \)[/tex] solution:

1. Understanding Molarity:
- Molarity (M) is defined as the number of moles of solute per liter of solution.
- Therefore,
[tex]\[ \text{Molarity (M)} = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \][/tex]

2. Given Values:
- Volume of the [tex]\( \text{BaCl}_2 \)[/tex] solution ([tex]\( \text{V}_{\text{solution}} \)[/tex]) = 200 mL
- First, we need to convert this volume into liters because the molarity is given in terms of liters.
- There are 1000 mL in 1 liter, so:
[tex]\[ 200 \, \text{mL} = \frac{200}{1000} = 0.2 \, \text{L} \][/tex]
- Molarity of the [tex]\( \text{BaCl}_2 \)[/tex] solution (M) = 0.10 M

3. Calculating Moles of [tex]\( \text{BaCl}_2 \)[/tex]:
- Now, use the molarity formula to find the number of moles of [tex]\( \text{BaCl}_2 \)[/tex]:
[tex]\[ \text{Moles of } \text{BaCl}_2 = \text{Molarity (M)} \times \text{Volume (L)} \][/tex]
- Plugging in the given values:
[tex]\[ \text{Moles of } \text{BaCl}_2 = 0.10 \, \text{M} \times 0.2 \, \text{L} \][/tex]

4. Performing the Multiplication:
- Simply multiply the two numbers to get the number of moles:
[tex]\[ \text{Moles of } \text{BaCl}_2 = 0.10 \times 0.2 = 0.020 \][/tex]

Therefore, the number of moles of [tex]\( \text{BaCl}_2 \)[/tex] present in 200 mL of a 0.10 M [tex]\( \text{BaCl}_2 \)[/tex] solution is:
[tex]\[ 0.020 \text{ moles} \][/tex]