- Balance the equation (If not already)
- Convert units of a given substance to moles.
- Using the mole ratio, calculate the moles of substance yielded by the reaction.
- Convert moles of wanted substance to desired units.
Mole Map for reference:
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| Mole Map |
Example: Zn + 2HCl --> ZnCl₂ + H₂
- How many grams of ZnCl₂ will be produced in the reaction of HCl with 0.350 moles of Zn?
0.350 mol Zn x 1 ZnCl₂/1 Zn = 0.350 mol ZnCl₂
0.350 mol ZnCl₂ x 135.4g/1 mol = 47.39 g ZnCl₂
Sig Fig = 47.4 g
Example: Ca(OH)₂ + H₂SO₃ --> CaSO₃ + 2H₂O
- How many particles of water can be produced from 47.6 g of Sulphurous acid (H₂SO₃) when sufficient Calcium hydroxide (Ca(OH)₂) is available?
47.6 g H₂SO₃ x 1 mol/82.1 g = 0.57978... mol H₂SO₃
0.57978 mol H₂SO₃ x 2 H₂O/1 H₂SO₃ = 1.15956... mol H₂O
1.15956 mol H₂O x 6.022x10²³/1 mol = 6.9828794x10²³ particles of H₂O
Sig Fig = 6.98x10²³ particles of H₂O
Example: 2Al +3Cl₂→2AlCl₃
- 80.0 g of Al is reacted with excess chlorine gas, how many formula units of AlCl₃ are produced?
80g Al x 1 mol/27g = 2.96 mol Al
2.96 mol Al x 2 AlCl₃/2 Al = 2.96 mol AlCl₃
2.96 mol AlCl₃ x 6.022x10²³/1 mol = 1.78x10²⁴
Sig Fig = 1.8x10²⁴ formula units of AlCl₃
Example: CO +2H₂→CH₃OH
- At STP, what volume of H₂ is needed to react completely with 8.02×10²³molecules of CO?
8.02×10²³molecules CO x 1 mol/6.022x10²³ = 1.3321... mol CO
1.3321 mol CO x 2 H₂/1 CO = 2.66423... mol H₂
2.66423 mol H₂ x 22.4 L STP/1 mol = 59.6787 L H₂
Sig Fig = 59.7 L H₂
Example: Cu + 2AgNO₃ --> Cu(NO₃)₂ + 2Ag
- How many g of Ag are formed when 16.2 g Cu react with sufficient AgNO₃?
0.255 mol Cu x 2 Ag/1 Cu = 0.510 mol Ag
0.510 mol Ag x 107.9 g/1 mol = 55.054 g
Sig Fig = 55.1 g of Ag
- How many atoms of Ag are formed when 2.5 mol Cu are reacted with sufficient AgNO₃?
2.5 mol Cu x 2 Ag/1 Cu = 5 mol Ag
5 mol Ag x 6.022x10²³/1 mol = 3.011x10²⁴
Sig Fig = 3.0x10²⁴ atoms Ag
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