Silver nitrate reacts with potassium chloride according as indicated by the balanced equation:
AgNO₃ + KCl -----> AgCl + KNO₃
How many grams of KCl would be required to react with 380 mL of 0.71 M AgNO₃ solution?.
First we have to find the number of moles in the solution of AgNO₃, then we can find the number of moles of KCl that will react with those moles of AgNO₃, and finally we can convert the moles of KCl into grams using the molar mass of KCl.
So, molarity is defined as the number of moles of solute divided the volume of solution in L.
Molarity = moles of AgNO₃/volume of solution in L
moles of AgNO₃ = molarity * volume of solution in L
We have 1000 mL in 1 L. We can use that conversion to find the volume of solution in L.
1000 mL = 1 L
Volume of solution in L = 380 mL * 1 L /1000 mL = 0.380 L
Volume of solution in L = 0.380 L
Now we can find the number of moles contained in 380 ml (or 0.380 L) of 0.71 M AgNO₃ solution.
moles of AgNO₃ = molarity * volume of solution in L
moles of AgNO₃ = 0.71 M * 0.380 L
moles of AgNO₃ = 0.270 moles
AgNO₃ + KCl -----> AgCl + KNO₃
We can compare the equation of a chemical reaction with a recipe. The coefficients are the quantities of that recipe. Since all the coefficients are 1, we can read our reaction like this: "1 mol of AgNO₃ will react with 1 mol of KCl to produce 1 mol of AgCl and 1 mol of KNO₃".
The reaction between AgNO₃ and KCl is 1 to 1. We will use that relationship to find the number of moles of KCl that will react with 0.270 moles of AgNO₃.
number of moles of KCl = 0.270 moles of AgNO₃ * 1 mol of KCl/(1 mol of AgNO₃)
number of moles of KCl = 0.270 moles of KCl
Since the reaction is 1 to 1, 0.270 moles of KCl will react with 0.270 moles of AgNO₃.
Finally we can find the mass of KCl. We need the molar mass of KCl.
atomic mass of K = 39.10 amu
atomic mass of Cl = 35.45 amu
molar mass of KCl = 74.55 g/mol
mass of KCl = number of molses of KCl * molar mass of KCl
mass of KCl = 0.270 moles * 74.55 g/mol
mass of KCl = 20.1 g
Answer: 20. g of KCl would be required.