Conversion Factors
divide by molar mass
If 3 moles of oxygen are reacted with excess hydrogen, what is the theoretical yield in moles?
2H2 + O2 => 2H2O
6 moles H2O
How many atoms of copper are produced when 4.8x10^18 atoms of aluminum are reacted with copper chloride?
3CuCl2 + 2Al -> 3Cu + 2AlCl3
7.2x10^18 atoms
4.8x10^18 x 3/2
What is the formula for percent yield?
(actual yield/theoretical yield) x 100
What is a reactant that is completely used up during a reaction?
limiting reaction
How do you convert liters of gas to moles
divide by 22.4L/mol
When 8.4mol of Aluminum sulfate are reacted with magnesium chloride, what is the theoretical yield of magnesium sulfate in moles?
3MgCl2 + Al2(SO4)3 => 3MgSO4 + 2AlCl3
25.2 moles
How many Liters of O2 are needed to produce 1.3mol of CO2?
C2H6O + 3O2 => 2CO2 + 3H2O
43.7L
1.3 x 3/2 x 22.4
After a reaction of copper sulfate with sodium carbonate, 3.53g of CuCO3 are weighed at the balance. If the theoretical yield of the CuCO3 was 4.2g, what is the percent yield?
CuSO4 + Na2CO3 => CuCO3 + Na2SO4
84%
3.53/42 x 100
When 4 moles of C are reacted with 13 moles O2, what is the limiting reagent?
2C + O2 => 2CO
Carbon
4 x 2/2 = 4
13 x 2/1 = 26
How do you convert moles to number of particles?
multiply by 6.02x10^23
What is the theoretical yield in grams, when 6.45g of H2 are reacted with excess N2?
N2 + 3H2 => 2NH3
36.6g NH3
6.45g x 1mol/2g x 2/3 x 17g/1mol
What mass of SrF2 can be prepared from the reaction of 50.0 g Sr(OH)2 with excess HF?
Sr(OH)2 + 2HF → SrF2 + 2H2O
51.6g
50/122 x 1/1 x 126
If 43.7g of copper sulfate reacts with an excess of aluminum, and the percent yield is 38%, what mass of aluminum sulfate was actually produced?
2Al + 3CuSO4 => 3Cu + Al2(SO4)3
11.6g
38 = actual/theoretical x 100
theoretical = 43.7/160 x 1/3 x 342 = 30.8g
actual/30.8 x 100 = 38
0.38x30.8
Which reactant is in excess when 20g of HCl are reacted with 20g of Li?
2HCl + 2Li => 2LiCl + H2
Li
20/7 x 1/1 excess
20/36 x 1/1 limit
How do you convert moles of MgCl2 to moles AlCl3?
3MgCl2 + Al2(SO4)3 => 3MgSO4 + 2AlCl3
multiply by 2/3
What is the theoretical yield of water in grams, when 48.3g of C2H6O are ignited in the presence of excess O2?
C2H6O + 3O2 => 2CO2 + 3H2O
56.7g
48.3/46 x 3/1 x 18
What volume (in liters) of ZnCl2 gas will be produced at STP when 127.3g of HCl are reacted with an excess of zinc metal?
Zn + 2HCl -> ZnCl2 + H2
39.6L
127.3/36 x 1/2 x 22.4
A chemistry student reacted 10g H2 with 30g N2, and isolated 20g of NH3. What was the percent yield?
N2 + 3H2 => 2NH3
56%
10/2 x 2/3 = 3.4
30/28 x 2/1 = 2.1 x 17 = 35.7
20/35.7 x 100
If 0.74g of Fe reacts with 0.38g of O2, which one is the limiting reactant?
3Fe + 2O2 => Fe3O4
Fe is the limit
0.74/56 x 1/3 = 0.004 limit
0.38/32 x 1/2 = 0.006 excess
How do you convert moles of tin to moles of hydrogen gas?
Sn + 2NaOH => Na2SnO2 + H2
multiply by 1/1
What is the theoretical yield (in grams) of K3PO4 when 67g H3PO4 is reacted with 26g KOH?
3KOH + H3PO4 => K3PO4 + 3H2O
32.8g
67/98 x 1/1 = .68
26/56 x 1/3 = .15 x 212
How many grams of hydrogen gas are needed to produce 268.3 g of water?
WO3 + 3H2 => W + 3H2O
29.8g
268.3/18 x 3/3 x 2/1
In the lab, 78g C was reacted with 80g O2, and 96g of product was collected. What was the percent yield?
2C + O2 => 2CO
68.6%
78/12 x 1/1 = 6.5
134/32 x 2/1 = 5 x 28 = 140
96/140 x 100
If 539g of tin reacts with 420g of sodium hydroxide, how many grams of Na2SnO2 will be produced?
Sn + 2NaOH => Na2SnO2 + H2
890.4g
539/119 x 1/1 = 4.52 mol Na2SnO2 limit
420/40 x 1/2 = 5.25 mol Na2SnO2
4.52 x 197