Answer
(a) 2.3
(b) 3.5
(c) 8.3
Work Step by Step
(a)
$\mathrm{p}\mathrm{H}_{lemon\ juice}=-\log_{10}[\mathrm{H}^{+}]=-\log(5.0\times 10^{-3})\approx 2.3$
(b)
$\mathrm{p}\mathrm{H}_{tomato\ juice}=-\log_{10}[\mathrm{H}^{+}]=-\log(3.2\times 10^{-4})\approx 3.5$
(c)
$\mathrm{p}\mathrm{H}_{seawater}=-\log_{10}[\mathrm{H}^{+}]=-\log(5.0\times 10^{-9})\approx 8.3$
