An unknown acid is titrated with a strong base. At the half-equivalence point (i. e., at the volume halfway to the equivalence point), the pH is 4.2. What is the pKa of the unknown acid?

14. complete and balance the equations for the single displacement reactions. a. zn + pb(no3)2 -> b. al + niso4 -> 15. complete and balance the equations for the double displacement reactions. a. agno3(aq) + nacl(aq) -> b. mg(no3)2(aq) + koh(aq) -> 16. complete and balance the equations for the combustion reactions. a. __ ch4 + o2 -> b. __ c3h6 + o2 -> c. + o2 ->

The melting point of sulfur is 115 °c and its boiling point is 445 °c. what state would sulfur be in at 200 °c?

What changes occur in the reaction indicated by the equation? check all that apply. the hydrogen nucleus loses protons. the oxygen nucleus gains protons. the bond in h2 is broken, and new bonds are formed between hydrogen and oxygen atoms. each electron associated with a hydrogen atom is shared with an oxygen atom.