Question

2AgNO3 (s) + MgCl2 (aq) --> 2AgCl (s) + Mg(NO3)2 (aq) The student starts with 50.0 grams of mgcl2 and an excess of AgNO3. If she makes 125.1g of AgCl, what is her percent yield?

Answer 1

The percent yield is 83.12%

calculation

percent yield = actual yield / theoretical yield x 100

actual yield =125.1 g

Theoretical yield is calculated as below

Step 1: find the moles of MgCl₂

moles = mass÷ molar mass

from periodic table the molar mass of mgCl₂ =24.3 +(35.5 x2) =95.3 g/mol

moles = 50.0 g÷ 95.3 g/mol =0.525 moles

Step 2: use the mole ratio to determine the moles of AgCl

from given equation MgCl₂: AgCl is 1:2

therefore the moles of AgCl = 0.525 x2/1 =1.05 moles

Step 3: find the theoretical mass AgCl

mass = moles x molar mass

from periodic table the molar mass of Agcl = 107.87 +35.5 =143.37 g/mol

mass = 1.05 moles x 143.37 g/mol =150.5 grams

The percent yield is therefore = (125.1 g/150.5) x 100 = 83.12%