A water sample was taken from a lake A 10000mL portion of th

A water sample was taken from a lake. A 100.00mL portion of this sample was pipetted into a 250mL Erlenmeyer flask. EriochromeBlack T-indicator, sodium cyanide, and ammonia buffer were also added to the flask. It required 24.24 mL of 0.0150M EDTA to reach the equivalence point of the titration. What is the molarity of hardness ions in the lake\'s water? SHOW your work please!

Solution

Lower in the morning.

Aquatic organisms in the lake will respire constantly, using up the oxygen.
However, during the day, the water plants in the lake will be undergoingphotosynthesis - producing oxygen, which will dissolve into the lake water over the course of the day.
Over night, there will be no photosynthesis (no sunlight), so the O2 levels will drop.