A groundwater (GW) was analyzed for ions and the results are reported below: Ca2+ = 200 mg/L (as Ca2+) Mg2+ = 60 mg/L (as Mg2+) Alkalinity = 400 mg CaCO3/L Assume the pH is near neutral a) What is the total hardness of the GW in mg CaCO3/L? b) What is the non-carbonate hardness of the GW in mg CaCO3/L? c) What is the carbonate hardness of the GW in mg CaCO3/L?? d) Would you recommend the GW be treated with a softening process prior to distribution to consumers? Why? List two treatment options.

Answer is given below.

Explanation:

Alkalinity = 400 mg/L in terms of CaCO3  

a.) Total Hardness is defined as the sum of calcium and magnesium iion concentration in terms of CaCO3

Total Hardness = [Ca+2]*{50/20) + [Mg+2]*{50/12) = [200]*{50/20) + [60]*{50/12) = 750 mg/L in terms of CaCO3

b.) Non-Carbonate hardness = Total Hardness - Carbonate Hardness

Now here as the Total Hardness is greater than alkalinity ,Thus

Carbonate Hardness = Alkanlinity = 400 mg/L in terms of CaCO3

Non-Carbonate hardness = 750 - 400 = 350 mg/L in terms of CaCO3

c.) As Total hardness is greater than Alkalinity thus Carbonate hardness is equal to the Alkalinity.

Carbonate hardness = 400 mg/L in terms of CaCO3

d.) Now as the Total hardness of the ground water is more than 180 mg/L,Thus it needs removal of hardness.

There are many treatment options for the removal of hardness:

i) Ion Exchange method

ii) Lime soda method

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

a is the answer to this question

explanation: