Potassium cyanide (KCN) reacts with acids to produce the poisonous hydrogen cyanide gas, HCN, according to the reaction below:
KCN(aq) + HCl(aq) = HCN(g) + KCl(aq)
If a sample of 0.653 g of KCN is placed in an excess of HCl, how much HCN, in grams, is produced?
Just follow the steps in this worked example.
http://www.jiskha.com/science/chemistry/stoichiometry.html
did u get the answer?
i have this exact same problem and i cannot figure out the answer. can you please help?
Follow the steps in the example.
To determine the amount of HCN produced, we need to use stoichiometry, which is the relationship between the moles of the reactants and products in a chemical reaction.
First, we calculate the number of moles of KCN. We can do this by dividing the given mass (0.653 g) by the molar mass of KCN.
The molar mass of KCN is calculated by adding the molar masses of potassium (K), carbon (C), and nitrogen (N). The atomic masses of K, C, and N are approximately 39.1 g/mol, 12.0 g/mol, and 14.0 g/mol, respectively.
Molar mass of KCN = 39.1 g/mol (K) + 12.0 g/mol (C) + 14.0 g/mol (N)
= 65.1 g/mol
Number of moles of KCN = Mass of KCN / Molar mass of KCN
= 0.653 g / 65.1 g/mol
≈ 0.01 mol
The balanced equation tells us that the stoichiometric ratio between KCN and HCN is 1:1. Therefore, the number of moles of HCN produced will also be 0.01 mol.
Now we need to find the mass of HCN produced. We can do this by multiplying the number of moles of HCN by its molar mass.
The molar mass of HCN is calculated by adding the molar masses of hydrogen (H), carbon (C), and nitrogen (N). The atomic masses of H, C, and N are approximately 1.0 g/mol, 12.0 g/mol, and 14.0 g/mol, respectively.
Molar mass of HCN = 1.0 g/mol (H) + 12.0 g/mol (C) + 14.0 g/mol (N)
= 27.0 g/mol
Mass of HCN = Number of moles of HCN × Molar mass of HCN
= 0.01 mol × 27.0 g/mol
= 0.27 g
Therefore, approximately 0.27 grams of HCN is produced.