7 – Chemistry HL Internal Assessment (IA) – May 2022

How does an increase in temperature (20.0, 40.0, 60.0, 80.0, 100.0°C) affect the calcium content (mg) in Brassica oleracea, variety acephala heated in a water bath for 360 seconds, as measured by direct EDTA complexometric titration using EBT indicator?

Introduction

Ever since my mother was diagnosed with calcium deficiency, our family started consuming more calcium- rich foods, one of them being collard greens. Collard greens (Brassica oleracea, variety acephala) are a type of leafy green vegetable, and their high calcium content is effective in for bone mineral accretion rate, preventing bone loss and osteoporosis fractures (Zhu and Prince). This is due to the fact that bones are primarily composed of calcium, which allows body movements by assuring flexible tissues (“Calcium”). My family discovered various ways to enjoy collard greens, but they are served raw or cooked most of

the times. One day, my mother read an article about reduced calcium content in heated vegetables; I then discovered that 100g of raw collard greens contain 232mg of calcium while the same amount, when boiled, contains only 141mg (“Collards, raw”; “Collards, cooked”). Knowing that heating somehow affects the vegetable’s calcium, this experiment was conducted to determine the specific heating temperature that would enable my family and anyone else to maximize health benefits from targeted consumption of collard greens.

Background Information

A direct complexometric titration of EDTA was repeated to determine
Ca2+ concentration in collard greens. This type of titration titrates the analyte with standard EDTA, using “the formation of a coloured complex to indicate the end of a titration,” while a complex is structure “consisting of a central atom or molecule connected to surrounding atoms or molecules (ligands)
by coordination bonds” (“Complexometric Determination”). Compounds with iminodiacetic acid functional groups are the most commonly used titrants, including ethylenediaminetetraacetic acid (EDTA) (Kozak)…