To extract gold from its ore, the ore is treated with sodium cyanide solution in the presence of oxygen and water.
4 Au(s) + 8 NaCN(aq) + O2(g) + 2 H2O(l) 4 NaAu(CN)2(aq) + 4 NaOH(aq)
Determine the mass of gold that can be extracted if 27.4 g sodium cyanide is used.
To determine the mass of gold that can be extracted if 27.4 g of sodium cyanide is used, we need to calculate the stoichiometric ratio between sodium cyanide and gold.
1. Calculate the molar mass of sodium cyanide (NaCN):
The molar mass of NaCN = atomic mass of Na + atomic mass of C + atomic mass of N
The atomic mass of Na = 22.99 g/mol
The atomic mass of C = 12.01 g/mol
The atomic mass of N = 14.01 g/mol
Therefore, the molar mass of NaCN = 22.99 + 12.01 + 14.01 = 49.01 g/mol
2. Determine the number of moles of sodium cyanide (NaCN):
Number of moles = Mass of NaCN / Molar mass of NaCN
Number of moles = 27.4 g / 49.01 g/mol
3. Use the stoichiometry of the balanced chemical equation to determine the number of moles of gold (Au):
According to the balanced equation, 4 moles of Au are produced for every 8 moles of NaCN used.
Therefore, the number of moles of Au = (Number of moles of NaCN / 8) * 4
4. Calculate the mass of gold (Au):
Mass of Au = Number of moles of Au * Molar mass of Au
The molar mass of Au = atomic mass of Au = 196.97 g/mol
Now, you can substitute the calculated values into the above equation to find the mass of gold that can be extracted.