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?

 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%

the answer is a and have a great day