Lecture 10-11 Flashcards
(32 cards)
why does Ontario have softer water then Saskatchewan?
Ontario has a lot of granite deposits. There are lower concentrations in granite then limestone so softer water. But lime is hard and ontario has problems with acid rain. There tend to be less health problems if you live near limestone
metal ion+ ligand <–>
complex ion
what is a multi-denate ligand/
a ligand with 2 or more binding sites (chelating sites) ex.) EDTA
what is a unidentate ligand?
a ligand with one binding site ex.) amine, carboxylate ion, monophosphate, phenoxide ion
why do kettles develop scales but coffee makers do not?
coffee makers only go up to 100 degrees C, whereas kettles can go up to 150-200 degrees C. The higher the heat the less soluble calcium carbonate or CaCO3 becomes.
how do you create softer water? draw equations out.
add line (Ca(OH)2) or soda ash (Na2CO3) to precipitate Ca2+
EDTA is an example of a what?
metal ligand
why does calcium sulphate impart permanent hardness?
because it cannot be removed by boiling
why is pH a poor measure of alkalinity?
- weak carbonate bases more abundant than hydroxide ions - Many natural waters not in equilibrium with the atmosphere
limestone compared to gypsum for hardness and alkalinity
limestone is hard and alkaline whereas gypsum is hard only
pH=
-loh (H+)
ionic strength?
measure of total concentration of ions in solution
pH+pOH=
14
what is the alkalinity of pure water if partial pressure of CO2= 370 ppm
0
describe when cadmium is found in soil or water
Cd is a very toxic, heavy metal. If it is present with OH it froms a solid. Or forms a ligand and goes to soil. If it finds H+ it would prefer the water phase.
calcium sulfate or CaSO4 is more or less prone to leave scales in hot water pipes compared to calcum carbonate?
less
what is the common unit of alklalinity?
CaCO3 mg/L
soda ash is added if hardness is mainly due to what?
calcium sulfate CaSO4
How do we determine equilibrium concentration of dissolved solids?
using Ksp
what is the alkalinity of natural water and what does that mean?
natural water typically has an alkalinity of 1.00 x 10-3 eq/L, meaning that the alkaline solutes in 1 L of the water will neutralize 1.00x10-3 mol of acid
what is another way to remove Ca2+
can use ion exchnager resins with negative ion exchanges. Using Na+ the calcium ions are washed out to drain along with NaCL.
hardness is usually measure by determining # of ions through …….
an EDTA titration
in freshwater, hardness and dissolved solids is due to what?
dissolution of rock
why does soft water mean acid rain?
low alkalinity in soft water areas means low buffering capacity for acid rain
