A student requires 2.00 L of [tex]0.100 \, \text{M} \, \text{NH}_4\text{NO}_3[/tex] from a [tex]1.75 \, \text{M} \, \text{NH}_4\text{NO}_3[/tex] stock solution. What is the correct way to get the solution?

A. Use [tex]M_1 V_1 = M_2 V_2[/tex]. Measure 14 mL of the 1.75 M solution and dilute to 1.00 L.

B. Measure 114 mL of the 1.75 M solution, and dilute it to 2.00 L.

C. Measure 8.75 mL of the 0.100 M solution, and dilute it to 2.00 L.



Answer :

To determine the correct method for preparing the solution, we need to use the dilution equation:

[tex]\[ M_1 \times V_1 = M_2 \times V_2 \][/tex]

where:
- [tex]\( M_1 \)[/tex] is the molarity of the stock solution (1.75 M),
- [tex]\( V_1 \)[/tex] is the volume of the stock solution needed,
- [tex]\( M_2 \)[/tex] is the molarity of the final solution (0.100 M),
- [tex]\( V_2 \)[/tex] is the volume of the final solution (2.00 L).

We need to solve for [tex]\( V_1 \)[/tex] (the volume of the 1.75 M stock solution):

1. Substitute the known values into the equation:

[tex]\[ 1.75 \, \text{M} \times V_1 = 0.100 \, \text{M} \times 2.00 \, \text{L} \][/tex]

2. Solve for [tex]\( V_1 \)[/tex]:

[tex]\[ V_1 = \frac{0.100 \, \text{M} \times 2.00 \, \text{L}}{1.75 \, \text{M}} \][/tex]

[tex]\[ V_1 = \frac{0.200 \, \text{M} \cdot \text{L}}{1.75 \, \text{M}} \][/tex]

[tex]\[ V_1 = 0.1142857142857143 \, \text{L} \][/tex]

3. Convert liters to milliliters (since 1 L = 1000 mL):

[tex]\[ V_1_{\text{ml}} = 0.1142857142857143 \, \text{L} \times 1000 \, \text{mL/L} \][/tex]

[tex]\[ V_1_{\text{ml}} = 114.28571428571429 \, \text{mL} \][/tex]

Therefore, you need to measure 114 mL of the 1.75 M stock solution and dilute it to a total volume of 2.00 L to obtain a 0.100 M solution.

This corresponds to the option:

Measure 114 mL of the 1.75 M solution, and dilute it to 2.00 L.