A student determines that an aqueous solution that contains 0.262 M potassium cyanide and 0.218 M hydrocyanic acid, also has an H3O+ concentration of 4.06×10-10 M. Based on these data, calculate the value of the equilibrium constant K for the equilibrium: HCN(aq) + H2O H3O+(aq) + CN-(aq)

Calculate K as is usually done, omitting the solvent, water, from the expression for K: K

The zinc within a copper-plated penny dissolves in hydrochloric acid if the copper coating is filed down in several spots (so that the hydrochloric acid can reach the zinc). the reaction between the acid and the zinc 2h+(aq)+zn(s)→h2(g)+zn2+(aq) . when the zinc in a certain penny dissolves, the total volume of gas collected over water at 25 °c is 0.947 l at a total pressure of 743 mmhg . (vapor pressure of water is 23.78 mmhg at 25 °c .) what mass of hydrogen gas is collected? answer in appropriate significant figures