Let's solve the problem step by step:
1. Convert the volume from milliliters to liters:
- The given volume is 125 mL.
- To convert milliliters to liters, we use the conversion factor:
[tex]\( \text{Volume (L)} = \text{Volume (mL)} \div 1000 \)[/tex]
- Thus, the volume in liters is:
[tex]\[ 125 \, \text{mL} \div 1000 = 0.125 \, \text{L} \][/tex]
2. Calculate the moles of NH4Cl required:
- The given concentration of the solution is 2.50 M (moles per liter).
- To find the moles, we use the formula:
[tex]\( \text{Moles} = \text{Volume (L)} \times \text{Concentration (M)} \)[/tex]
- Substituting in the values, we get:
[tex]\[ 0.125 \, \text{L} \times 2.50 \, \text{M} = 0.3125 \, \text{moles} \][/tex]
3. Calculate the molar mass of NH4Cl:
- NH4Cl consists of one nitrogen (N), four hydrogens (H), and one chlorine (Cl).
- The atomic masses are approximately:
- Nitrogen (N) = 14 g/mol
- Hydrogen (H) = 1 g/mol
- Chlorine (Cl) = 35.5 g/mol
- The molar mass of NH4Cl is:
[tex]\[ 14 + (4 \times 1) + 35.5 = 14 + 4 + 35.5 = 53.5 \, \text{g/mol} \][/tex]
4. Calculate the grams of NH4Cl required:
- We use the formula:
[tex]\( \text{Mass (g)} = \text{Moles} \times \text{Molar mass (g/mol)} \)[/tex]
- Substituting the values, we get:
[tex]\[ 0.3125 \, \text{moles} \times 53.5 \, \text{g/mol} = 16.71875 \, \text{grams} \][/tex]
Therefore, you need 16.71875 grams of NH4Cl to make 125 mL of a 2.50 M NH4Cl solution.
