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.
If the mass of the ore from which the gold was extracted is 157.0 g, what percentage of the ore is gold?
No arrow again and there is no space for one. You can do this unless you know the reactants and the products.
Use the same procedure as for the Na + Fe2O3 and air bag problem.
For the percent Au in the ore, (mass Au extracted/mass ore)*100 =
To determine the mass of gold that can be extracted, we need to calculate the stoichiometry of the reaction and use it to convert the given mass of sodium cyanide to the mass of gold.
First, we need to calculate the molar mass of NaCN and Au.
The molar mass of NaCN is:
Sodium (Na): 22.99 g/mol
Carbon (C): 12.01 g/mol
Nitrogen (N): 14.01 g/mol
So the molar mass of NaCN is:
(22.99 g/mol) + (12.01 g/mol) + (14.01 g/mol) = 49.01 g/mol
The molar mass of gold (Au) is 196.97 g/mol.
Now, we can calculate the moles of NaCN used:
moles of NaCN = mass of NaCN / molar mass of NaCN
moles of NaCN = 27.4 g / 49.01 g/mol
moles of NaCN ≈ 0.559 mol
From the balanced equation, we can see that the mole ratio between NaCN and Au is 8:4, or 2:1. This means that for every 2 moles of NaCN used, 1 mole of Au is obtained.
So the moles of Au obtained are:
moles of Au = (moles of NaCN) / 2
moles of Au = (0.559 mol) / 2
moles of Au ≈ 0.279 mol
Now, we can calculate the mass of Au obtained:
mass of Au = moles of Au * molar mass of Au
mass of Au = 0.279 mol * 196.97 g/mol
mass of Au ≈ 55.0 g
Therefore, the mass of gold that can be extracted is approximately 55.0 grams.
To calculate the percentage of gold in the ore, we can use the equation:
percentage of gold = (mass of gold / mass of ore) * 100
Given that the mass of the ore is 157.0 g, we can substitute the values:
percentage of gold = (55.0 g / 157.0 g) * 100
percentage of gold ≈ 35.0%
Therefore, the ore contains approximately 35.0% gold.
To determine the mass of gold that can be extracted, we first need to find the molar mass of sodium cyanide (NaCN).
The molar mass of NaCN can be calculated as follows:
Sodium (Na): Atomic mass = 22.99 g/mol
Carbon (C): Atomic mass = 12.01 g/mol
Nitrogen (N): Atomic mass = 14.01 g/mol
Molar mass of NaCN = (22.99 g/mol) + (12.01 g/mol) + (14.01 g/mol) = 49.01 g/mol
Now, let's calculate the number of moles of sodium cyanide used in the reaction.
Number of moles = mass / molar mass
Number of moles of NaCN = 27.4 g / 49.01 g/mol = 0.559 mol
According to the balanced chemical equation, 8 moles of NaCN react with 4 moles of Au. Therefore, the number of moles of Au can be calculated using the mole ratio.
Moles of Au = (0.559 mol NaCN) * (4 mol Au / 8 mol NaCN) = 0.2795 mol Au
To find the mass of gold extracted, we need to multiply the number of moles of gold by the molar mass of gold (Au).
The molar mass of Au is 196.97 g/mol.
Mass of gold = Moles of Au * Molar mass of Au
Mass of gold = 0.2795 mol Au * 196.97 g/mol = 55.08 g
Therefore, the mass of gold that can be extracted from 27.4 g of sodium cyanide is 55.08 g.
To calculate the percentage of gold in the ore, we need to divide the mass of gold extracted by the mass of the ore and multiply by 100.
Percentage of gold in the ore = (Mass of gold / Mass of the ore) * 100
Percentage of gold in the ore = (55.08 g / 157.0 g) * 100 = 35.08%
Therefore, the percentage of gold in the ore is 35.08%.