A water sample from a lake has a measured alkalinity of $0\mathrm{.}8$ meq$/$L$.$ In the early morning, a monitoring team measures the lake$’$s pH as part of the acid rain study and finds a pH of $6\mathrm{.}0.$ The survey team returns aLer lunch to recheck their data. By this Nme, algae and other aquaNc plants have consumed enough dissolved CO$2$ to reduce the lake$’$s total carbonate $($CT$)$ to one$-$half of its morning value.

$•$ What was the morning value for CT$?$

$•$ What was the pH aLer lunch?

$2.$ Water sample analysis indicated a total carbonate concentraNon of $0\mathrm{.}003$ mol$/$L and a pH of $6\mathrm{.}6.$ What is the alkalinity in meq$/$L and in mg$/$L$?$

$3.$ If $1$ L of the above sample is diluted with enough pure water to change the total carbonate concentraNon to $0\mathrm{.}0025$ mol$/$L$,$ what would be the new pH and alkalinity?

$4.$ A water sample contains $44$ mg$/$L of calcium and $19$ mg$/$L of magnesium ions. What is the hardness expressed as mg$/$L of CaCO$3?$