Answer:
12.5 mL NH₃
Step-by-step explanation:
To find the volume of NH₃, you need to (1) find the moles (NH₄)₂PtCl₄ (using the molarity equation), then (2) convert moles (NH₄)₂PtCl₄ to moles NH₃ (via mole-to-mole ratio from balanced equation, and then (3) find the volume NH₃ (using the molarity equation).
(Step 1)
25.00 mL / 1,000 = 0.025 L
Molarity = moles / volume (L)
0.100 M = moles / 0.025 L
0.0025 = moles (NH₄)₂PtCl₄
(Step 2)
The unbalanced equation:
(NH₄)₂PtCl₄ + NH₃ ----> Pt(NH₃)₂Cl₂ + NH₄Cl
Reactants: 2 nitrogen, 11 hydrogen, 1 platinum, 4 chlorine
Products: 2 nitrogen, 10 hydrogen, 1 platinum, 3 chlorine
The balanced equation:
(NH₄)₂PtCl₄ + 2 NH₃ ----> Pt(NH₃)₂Cl₂ + 2 NH₄Cl
Reactants: 3 nitrogen, 14 hydrogen, 1 platinum, 4 chlorine
Products: 2 nitrogen, 14 hydrogen, 1 platinum, 4 chlorine
0.0025 moles (NH₄)₂PtCl₄ 2 moles NH₃
---------------------------------------- x ------------------------------ = 0.0050 moles NH₃
1 mole (NH₄)₂PtCl₄
(Step 3)
Molarity = moles / volume (L)
0.400 M = 0.0050 moles / volume
(0.400 M) x volume = 0.0050 moles
volume = 0.0125 L NH₃
0.0125 L x 1,000 = 12.5 mL NH₃