A chemistry graduate student is given of a hydrocyanic acid solution. Hydrocyanic acid is a weak acid with . What mass of should the student dissolve in the solution to turn it into a buffer with pH

Here is the full question:

A chemistry graduate student was given 500 mL of a 1.60 M hydrocyanic acid (HCN) solution. Hydrocyanic acid is a weak acid with . What mass of KCN should the student dissolve in the HCN solution to turn it into a buffer with pH  = 9.16?

36.85 g

Explanation:

From the given information above:

Recall that  number of moles of HCN = mass of HCN / molar mass of HCN= mass of HCN / molar mass of HCN

Therefore;

the number of moles of HCN =  

the number of moles of HCN =

the number of moles of HCN =  0.8

The acid dissociation constant =

Thus the pKa =

pKa = 9.31

However, the pH is given as:

KCN = 0.566 mol

The standard molar mass of KCN = 65.11 g/mol

Thus, the mass of KCN = number of moles of KCN × molar mass of KCN

the mass of KCN = 0.566 × 65.11

the mass of KCN that the student needs to dissolve in HCN is =  36.85 g

water is used to store them because it would keep the radiation from getting out in the open and causing harm to the workers

if you mean hydrogen and oxygen then water is the product