20 mL of sodium iodide solution gave 4.74 g silver iodide when treated with excess of silver nitrate solution. The molarity of the sodium iodide solution is ______ M. (Nearest integer value)
Given: Na = 23, I = 127, Ag = 108, N = 14, O = 16 g mol⁻¹
NaI + AgNO₃ → AgI ↓ + NaNO₃
Molar mass of AgI = 108 + 127 = 235 g mol⁻¹
Moles of AgI = 4.74 / 235 = 0.0202 moles
From the equation, 1 mole of NaI produces 1 mole of AgI.
So, moles of NaI = 0.0202 moles
Volume of NaI solution = 20 mL = 0.020 L
Molarity = moles / volume = 0.0202 / 0.020
≈ 1.01 M
Molarity ≈ 1 M
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