Question

The cyanide ion (CN-1) is highly toxic, but can be remediated in solution by redox reaction with the hypochlorite ion (the principal component of bleach). The balanced net ionic equation for this process is: 2 CN-1 + 5 ClO-1 + H2O ---> 5 Cl-1 + N2 + 2 HCO3 -1 A 3.5 x 106 L sample of water was found to be contaminated with cyanide ions at a concentration of 25mM. How many grams of cyanide were dissolved in the total sample?

Answer 1

2.275x10⁶g of CN⁻¹ were dissolved in the sample

Step-by-step explanation:

Molarity is defined as the ratio between moles of solute and liters of solution.

If a CN⁻¹ solution has a concentration of 25mM, there are 0.025 moles of CN⁻¹ per liter of solution.

If the sample has a colume of 3.5x10⁶L, moles of CN⁻¹ are:

3.5x10⁶L × (0.025moles / L) = 8.75x10⁴ moles of CN⁻¹ in the sample of water.

In grams (As molar mass of CN⁻¹ is 26g/mol):

8.75x10⁴ moles CN⁻¹ × (26g / mol) = 2.275x10⁶g of CN⁻¹ were dissolved in the sample