Formal Laboratory Report: The Chemistry Of Water

Formal Laboratory Report

The Chemistry of Natural Waters

Submitted by: Yihua Huang

Lab Partners: Leslie Johnson, Thomas Jaramillo,

Andrea Hurtado

Chemistry 111 Section 101

October 19, 2015

TA: Nabeel Ahmed

Section I: Introduction:

Today, hydrologic cycle is one of the most important component to support people’s life. There are more than one billion people are lack of clean drinking water.1 A person need about 80 liters of water every day to maintain a basic quality life.2

The presence of the dissolved cations (like Ca2+, Mg 2+, and other cations) gives water the chemical property called water hardness. Hard water contains very high concentration of dissolved cations. Conversely. Soft water contains very low concentration of

Owing to hard water can cause a lot of issues in real life. If people use hard water to wash dishes, it can leave spots on the bowls and plates. Also, hard water cause issues a lot for water boilers. The Ca2+ and Mg2+ will form a scale that makes the water boiler inefficient to work. Moreover, because of hard water contains soluble sedimentary rocks like limestone(CaCO3), pipes with scale can reduce the water flow. This problem increases the energy bills about 25%.3

The hardness of water can be determined by many scientific techniques.

Atomic Absorption Spectrophotometry(AA) is useful to determine metals dissolved in a solution. The chemical principle behind AA is the Beer-Lambert Law. It can be easily used to calculate the metal concentration in the water sample. Atoms have energy levels are unique. Atoms need to be matched the energy of light falling on them to be excited.3

EDTA Titration is another technique to determine metals dissolved in water. Different from AA, it analyzed all cations presented in water, instead of just Ca2+ and Mg2+. 3

Another water to determine water hardness is called Total Dissolved Solids (TDS). It measures the amount of residue that was left in a known amount of water after