Conversions
What do you use to convert from grams to moles?
molar mass
What is concentration?
describes the amount of a substance dissolved in solution, with units of Molarity or M
What does it mean to dilute something?
What do you need to be able to calculate percent yield?
actual yield and theoretical yield
How do you convert from moles to molecules?
using Avogadro's number
What is the "equation" for molarity?
M = moles of solute/liters of solution
What equation is used when we talk about dilutions?
M1V1 = M2V2 or MiVi = MfVf
What is the equation for percent yield?
(actual yield/theoretical yield) x 100% = percent yield
2 Mg (s) + O2 (g) --> 2 MgO (s)
How many moles of MgO form if 2.0 moles of oxygen are consumed?
4.0 moles MgO
Problem: 40.0 g of anhydrous CuSO4 are completely dissolved in
250.00 mL of water using a volumetric flask.
What is the concentration of the prepared solution?
What is the first step to solving this problem?
Convert 40.0 g of CuSO4 into moles of CuSO4
Problem: 50.00 mL of a 1.00 M stock solution is transferred and
diluted to a new volume of 200.00 mL.
What is the concentration of the new solution?
What is the first step to solving this problem?
Write down values.
M1 or Mi = 1.00 M
V1 or Vi = 50.00 mL
V2 or Vf = 200.00 mL
Problem: A chemist runs a reaction in which the theoretical yield is 294.8 grams. However, they are
only able to isolate 175 grams. What is the percent yield for this reaction?
What is the first step to solving this problem?
Write down your given information.
Theoretical yield = 294.8 grams
2 Mg (s) + O2 (g) --> 2 MgO (s)
How many moles of MgO are produced when starting with 3.0 moles of magnesium?
3.0 moles MgO
Problem: 39.9 g of anhydrous CuSO4 are completely dissolved in
250.00 mL of water using a volumetric flask.
What is the concentration of the prepared solution?
What is the second step to solving this problem?
Convert 250.00 mL to liters
Problem: 50.00 mL of a 1.00 M stock solution is transferred and
diluted to a new volume of 200.00 mL.
What is the concentration of the new solution?
What is the next step to solving this problem?
Plug your numbers into the equation:
(1.00 M)(50.00mL) = M2(200.00mL)
Problem: A chemist runs a reaction in which the theoretical yield is 294.8 grams. However, they are
only able to isolate 175 grams. What is the percent yield for this reaction?
What is the second step to solving this problem?
Pick out key words.
"only able to isolate" means actual yield,
actual yield = 175 grams
2 Mg (s) + O2 (g) --> 2 MgO (s)
How many grams of MgO are formed if 2.0 moles of oxygen are consumed?
320 grams MgO
Problem: 39.9 g of anhydrous CuSO4 are completely dissolved in
250.00 mL of water using a volumetric flask.
What is the concentration of the prepared solution?
What is the final step to solving this problem?
Using moles obtained from Step 1 and liters obtained from Step 2, calculate the concentration
(1.00 M)(50.00mL) = M2(200.00mL)
How do you obtain M2 or Mf?
Divide both sides by 200.00 mL, cancelling units
Problem: A chemist runs a reaction in which the theoretical yield is 294.8 grams. However, they are
only able to isolate 175 grams. What is the percent yield for this reaction?
What is the final step to solving this problem?
Plug your values into the equation and solve:
(175 g/294.8 g) x 100% = percent yield