Question

During the lab, you measured the pH of common household items. Write net Brønsted equations that show the acidic or basic nature of the following substances, given thepH. For polyprotic acids, only show one proton transfer. Remember that spectator ions are not included. (Use the lowest possible coefficients. Omit states-of-matter inyour answer.)
(a) lithium hydrogenphosphate with a pH of 9.70

(b) lithium hydrogensulfide with a pH of 9.90

(c) apple (malic acid, H2C4H4O5) with a pH of 3.90

(d) milk (lactic acid, HC3H5O3) with a pH of 6.60

Answer 1

a bronstead net equation shows a molecule of the acid reacting with H2O to show which is donating the H ion. the acid will donate, and the base will acceptit.
a. since lithium hydrogen phosphate has a ph of 9.70, it will be receiving a H, as it is basic.
Li2HPO4 + 2H2O = H3PO4 + 2LiHO because H2O lost the H atom and Li2HPO4 gained it, showing which is the acid and which is the base.
b. LiHSO4 + H2O = LiOH + H2SO4 the same is true with this one, the LiHSO4 gained a H atom and water lost one.
c. H2C4H4O5 + H2O = HC4H4O5 + H3O the maltic acid is donating a H atom to the water, showing us which is the acid and base.
d.HC3H5O3 + H2O = C3H5O3 + H3O the lactic acid is donating a H atom, and the water is accepting; the lactic acid is the acid, and H2O is the base.
I hope this helped.