When potassium cyanide (KCN) reacts with acids, a deadly poisonous gas, hydrogen cyanide (HCN), is given off. Here is the equation:
KCN(aq) + HCI(aq) -> KCI(aq) + HCN (g)
In a sample of 0.140 grams of KCN is treated with an excess of HCI calculate the amount of HCN formed in grams.
Please explain the work and the answers.
How many moles of KCN do you start with? YOu get the same number of moles of HCN.
Can you clarify do I get the moles of KCN by .14 grams of KCN/ 65.02 grams of KCN. How do I get the moles of KCN?
To calculate the amount of HCN formed in grams, you'll need to use stoichiometry and the given mass of KCN.
Here are the steps to solve the problem:
Step 1: Determine the molar mass of KCN:
The molar mass of KCN is calculated by summing the atomic masses of potassium (K), carbon (C), and nitrogen (N). Looking up these values on the periodic table:
K: 39.10 g/mol
C: 12.01 g/mol
N: 14.01 g/mol
Molar mass of KCN = (1 * K) + (1 * C) + (1 * N)
Molar mass of KCN = 39.10 + 12.01 + 14.01 = 65.12 g/mol
Step 2: Convert the given mass of KCN to moles:
Given mass of KCN = 0.140 grams
Number of moles of KCN = Given mass / Molar mass
Number of moles of KCN = 0.140 g / 65.12 g/mol ≈ 0.00215 mol
Step 3: Use the balanced chemical equation to establish the stoichiometric ratio between KCN and HCN:
According to the balanced equation:
1 mol of KCN produces 1 mol of HCN
Step 4: Calculate the amount of HCN formed in moles:
Number of moles of HCN = Number of moles of KCN
Number of moles of HCN ≈ 0.00215 mol
Step 5: Convert the moles of HCN to grams using its molar mass:
The molar mass of HCN is calculated by summing the atomic masses of hydrogen (H), carbon (C), and nitrogen (N):
H: 1.01 g/mol
C: 12.01 g/mol
N: 14.01 g/mol
Molar mass of HCN = (1 * H) + (1 * C) + (1 * N)
Molar mass of HCN = 1.01 + 12.01 + 14.01 = 27.03 g/mol
Mass of HCN formed = Number of moles of HCN * Molar mass of HCN
Mass of HCN formed ≈ 0.00215 mol * 27.03 g/mol ≈ 0.0581 grams
Therefore, approximately 0.0581 grams of HCN is formed when 0.140 grams of KCN is reacted with an excess of HCl.