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STOIC
HIOM
ETRY
CALCULA
TIONS
CO
AC
H C
OX
MOLE TO MOLE CONVERSIONS
Converting from moles of one substance in a chemical reaction to moles of another substance in a chemical reaction
MOLE TO MOLE: EXAMPLE 1
If you dropped 0.040 moles of potassium into a beaker of water, how many moles of hydrogen would you produce?
Step 1: Write a balanced chemical equation.
____K(s) + ____ H2O(l) ____ KOH(aq) + ____ H2(g)
Step 2: Start with your known, and use Dimensional Analysis with the correct mole ratio from the balanced equation to find the unknown
- Draw your pathway!
MOLE TO MOLE: EXAMPLE 1 ANSWER
Balanced Equation: 2K(s) + 2 H2O(l) 2 KOH(aq) + 1 H2(g)
1 mol H2
Pathway: 0.040 mol K ------------------------------------> moles of H2
2 mol K
0.040 mol K x 1 mol H2 = .02 mol H2 produced
2 mol K
MOLE TO MOLE: EXAMPLE 2
Using the same number of moles of potassium, how many moles of H2O will be used?
Balanced Equation: 2K(s) + 2 H2O(l) 2 KOH(aq) + 1 H2(g)
Work out the question the exact same way you did Example 1!
MOLE TO MOLE: EXAMPLE 2 ANSWER
Balanced Equation: 2K(s) + 2 H2O(l) 2 KOH(aq) + 1 H2(g)
2 mol H2O
Pathway: 0.040 mol K ------------------------------------> moles of H2O
2 mol K
0.040 mol K x 2 mol H2O = .04 mol H2O will be used
2 mol K
MOLE TO MOLE: EXAMPLE 3
One disadvantage of burning propane, C3H8, is that CO2 is produced as a product. The released CO2 increases the growing concentration of carbon dioxide in the atmosphere. How many moles of CO2 are produced when 10.45 moles of C3H8 is burned in a propane gas grill?
___ C3H8(g) + ___ O2(g) ___ CO2(g) + ___ H2O(l)
Work it out the same way, balance the equation first!
MOLE TO MOLE: EXAMPLE 3 ANSWER
Balanced Equation: 1 C3H8(g) + 5 O2(g) 3 CO2(g) + 4 H2O(g)
3 mol CO2
Pathway: 10.45 mol C3H8 ------------------------------------> moles of CO2 1 mol C3H8
10.45 mol C3H8 x 3 mol CO2 = 31.35 mol CO2 will be produced
1 mol C3H8
MOLE TO MOLE: EXAMPLE 4
The reaction between methane and, CH4, and sulfur produces carbon disulfide, CS2, a liquid used in the production of cellophane.
___CH4 + ___S8 ___CS2 + ___H2S
a. Balance the equation.
b. Calculate the moles of CS2 produced when 1.78 moles of S8 is consumed.
c. How many moles of H2S is produced during this same reaction?
MOLE TO MOLE: EXAMPLE 4 ANSWER
a. Balanced Equation: 2 CH4 + 1 S8 2 CS2 + 4 H2S
b. 1.78 mol S8 x 2 mol CS2 = 3.56 mol CS2 will be produced
1 mol S8
c. 1.78 mol S8 x 4 mol H2S = 7.12 mol H2S will be produced
1 mol S8
MOLE TO MASS CONVERSIONS
Converting from moles of one substance in a chemical reaction to mass of another substance in a chemical reaction
MOLE TO MASS EXAMPLE 1
Determine the mass of NaCl produced when 1.25 moles of chlorine gas reacts with sodium
Step 1: Write a balanced equation
___ Cl2 + ___ Na ___ NaCl
Step 2: Start with your known, and use Dimensional Analysis with the correct mole ratio from the balanced equation to find the unknown
- Draw your pathway!
MOLE TO MASS: EXAMPLE 1 ANSWER
Balanced Equation: 1 Cl2 + 2 Na 2 NaCl
Pathway: 1.25 mol Cl2 ------------------------------------------> grams NaCl produced
1.25 mol Cl2 x 2 mol NaCl x 58.443 g NaCl = 146.11 grams NaCl produced
1 mol Cl2 1 mol NaCl
MOLE TO MASS EXAMPLE 2
Determine the mass of the sodium needed to complete this same reaction.
Balanced Equation: 1 Cl2 + 2 Na 2 NaCl
Work out the question the exact same way you did Example 1!
MOLE TO MASS: EXAMPLE 2 ANSWER
Balanced Equation: 1 Cl2 + 2 Na 2 NaCl
Pathway: 1.25 mol Cl2 ------------------------------------------> grams Na needed
1.25 mol Cl2 x 2 mol Na x 22.990 g Na = 57.475 grams Na needed
1 mol Cl2 1 mol Na
MASS TO MASS CONVERSIONS
Converting from the mass of one substance in a chemical reaction to the mass of another substance in a chemical reaction
MASS TO MASS CONVERSIONS
EVERYTHING MUST GO THROUGH MOLES!!!
(MOLE TO MOLE conversions)
MASS TO MASS EXAMPLE 1
Determine the mass of H2O produced from the decomposition of 25.0 g of ammonium nitrate (NH4NO3)
Step 1: Write a balanced equation
___ NH4NO3 ___ H2O + ___ N2O
Step 2: Start with your known, and use Dimensional Analysis to convert from:
a. mass of known to moles of known using the periodic table
b. moles of known to moles or unknown using the correct mole ratio moles to
mass of the unknown using the periodic table
- Draw your pathway!
MASS TO MASS: EXAMPLE 1 ANSWER
Balanced Equation: 1 NH4NO3 2 H2O + 1 N2O
Pathway: 25 g NH4NO3 ---------------------------------------> grams H2O produced
25 g NH4NO3 x 1 mol NH4NO3 x 2 mol H2O x 18.015 g H2O = 97.829 g NH4NO3 1 mol NH4NO3 1 mol H2O
= 9.207 grams of H2O produced
MASS TO MASS EXAMPLE 2
Calculate the number of grams of NH3 produced by the reaction of 5.4 g of hydrogen with an excess of nitrogen
___ N2(g) + ___ H2(g) ___ NH3(g)
MASS TO MASS: EXAMPLE 2 ANSWER
Balanced Equation: 1 N2(g) + 3 H2(g) 2 NH3(g)
Pathway: 5.4 g H2 ---------------------------------------> grams NH3 produced
5.4 g H2 x 1 mol H2 x 2 mol NH3 x 17.031 g NH3 = 2.016 g H2 1 mol H2 1 mol NH3
= 91.2375 grams of NH3 produced
PARTICLES TO PARTICLES CONVERSIONS
Converting from the particles of one substance in a chemical reaction to the particles of another substance in a chemical reaction
PARTICLES TO PARTICLES CONVERSIONS
EVERYTHING MUST GO THROUGH MOLES!!!
(MOLE TO MOLE conversions)
PARTICLES TO PARTICLES CONVERSIONS: EXAMPLE 1
Sodium hydrogen carbonate decomposes with heat to produce carbon dioxide gas, water, and solid sodium carbonate. 2.2 x 1023 formula units of sodium hydrogen carbonate react to form ________ molecules of carbon dioxide.
___ NaHCO3(s) ___ Na2CO3(s) + ___ CO2(g) + ___ H2O(g)
PARTICLES TO PARTICLES CONVERSIONS: EXAMPLE 1ANSWER
Balanced Equation: 2 NaHCO3(s) 1 Na2CO3(s) + 1 CO2(g) + 1 H2O(g)
Pathway: 2.2 x 1023 fun NaHCO3 ---------------------------------------> molecules CO2
2.2 x 1023 fun NaHCO3 x 1 mol NaHCO3 x 1 mol CO2 x 6.02x1023 molecules CO2 = 6.02x1023 fun NaHCO3 2 mol NaHCO3 1 mol CO2
= 1.1 x 1023 molecules of CO2 produced
