How could you determine the concentration of a specific molecule, ion or active ingredient in a household item?

Background information

Household Items

Household items are classified as goods, including technology, furniture and chemicals such as cleaning products kept and typically used within and around the home (Law Insider, 2024).Examples of household items include

Experiments

Methods to determine concentration

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Lemon juice is a solution that may be used within households for a variety of reasons, including cooking, cleaning (specifically removing stains) and as an air freshener. Citric acid C6H8O7 is a component of lemon, which provides its sour taste, and acidity.

Spectrophotometry is a method of determining concentration regarding the amount of light a substance absorbs. Specifically, a light beam of a particular wavelength through a sample of the substance and measuring the intensity of the beam both prior and post passing through the substance (Vo, 2013). According to Beer-Lambert's Law, the difference in intensity is proportional to the concentration of the substance and when the absorbance is compared to a calibration curve (a graph curve consisting of points of known substances at multiple concentrations), measured with the assistance of a spectrophotometer, concentration can be calculated (excedr, 2023).

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Titration: Titration can be described as the gradual addition of a solution with a known concentration (titrant) to another solution with unknown concentration (analyte) until the reaction is completely neutralised. This is typically indicated by a colour change through an indicator or pH metre. After conducting a titration reaction, the analytes concentration can be calculated using stoichiometry.

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Limitations of this method include the inability to determine the endpoint, as colour change may not be precise, especially if the solution is opaque. Furthermore, titrations are limited to certain types of reactions (acid-base, redox and precipitation), are time consuming and require expensive equipment, such as scales (Chemistry LibreTexts, 2013).

Gravimetric analysis: This method determines the quantity of the analyte based on its mass. The procedure for performing this analysis begins with dissolving a sample containing an analyte being part of a solution (BYJUS, n.d.). Precipitation is formed through the addition of a regent, developing the solid compound that is isolated from the remainder of the solution through filtration. The solid is then weighed in order to determine the original amount of analyte prevalent in the sample.

While this method is accurate, it only allows for the calculation of a single substance at a time(Britannica Kids, 2024).

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This experiment will involve figuring which brand of bottled lemon juice (out of three options) will have the most concentration of citric acid. IV: brand of lemon juice DV: concentration of citric acid. CV:CV: concentration of titrant, volume of lemon juice, same type of indicator. Method: titration Justification: It can accurately measure the concentration of citric acid in lemon juice by determining the end point of the titration.

The function of moisturiser is to hydrate dry skin and retain moisture (Purnamawati, 2017). Moisturiser establishes the process of hydration, directly providing water to skin, increasing obstruction to reduce trans-epidermal water loss (when water evaporates through the skin into air) and also forming protective film, preventing friction affecting the skin. Glycerine is an active ingredient within moisturiser that escalates water retention within the skin assisting to preserve hydrated skin (cerave, n.d.).

To determine which brand of moisturiser has the highest concentration of glycerin. IV: brand of moisturiser DV:concentration of glycerin Method: spectrophotometry Justification: spectrophotometry is best when handling complex mixtures (moisturisers), allowing the concentration of glycerin to be measured through the absorbance of a specific light wavelength. CV: wavelength, instrument settings, concentration range, solvent.

Batteries are energy sources that store chemical energy and convert it into electrical energy, specifically through the flow of electrons from one material to another via an external circuit. This flow provides a current that can be used to do work and in households, batteries are utilised within technology, such as clocks, remotes, radios or clocks (Australian Academy of Science, 2016). Manganese oxide (MnO₂) is an inorganic compound within batteries due to being a depolarising agent for batteries, meaning it pertains to the characteristics of large discharge capacity, small volume and long service life, enabling it to be a critical component of modern batteries(Made-in-China.com, 2024).

Aim: To determine which type of battery will obtain the highest concentration of manganese oxide. IV: the type of battery. DV: the concentration of manganese oxide. CV: sample size, chemicals and reagents, preparation method. Method: gravimetric analysis Justification: Gravimetric analysis involves weighing the mass of a substance, which can be done when precipitation the manganese, which can be weighed to determine the amount present in this experiment.

Molecules are the smallest unit of chemical substances, composed of one or more atoms chemically bonded. Atoms are the building blocks of molecules that consist of a nucleus filled with protons and neutrons and are surrounded by electron shells of differing energy levels, where electrons orbit around the nucleus. Molecules are formed according to the arrangement of valence electrons, located in the outermost energy level of the atom. Specifically, the primary bonds that assemble molecules are covalent bonding, where two atoms share at least one electron pair and ionic bonding, that occurs as an atom transfers an electron to another atom. The properties of molecules are determined by the type of atoms concerned with the molecule, as different elements possess varying properties, as well as the strength and nature of the chemical bonds within the molecule influencing its stability and reactivity. Molecules can be synthesised and influenced to create everyday household products(National Cancer Institute, 2011).

Ions are atoms or molecules that have either gained or lost electrons, which results in a net electrical charge. The two main types of ions are cations and anions. Cations form as an atom or molecule discard one one or more negative electrons and overall become positively charged. Anions are negatively charged atoms that have gained one or more electrons. Ions can be formed through ionisation, which is the process where an energy source, such as heat or light forces atoms to either gain or lose electrons, Furthermore, during chemical reactions, in order to achieve a stable valence shell, atoms transfer electrons to each other. Ions possess various properties such as the capability to conduct electricity, undergo chemical reactions and form crystalline structures. Ions are used within various household products such as toothpaste and table salt (medlineplus, n.d.).

Active ingredients are components within a product that are accountable for its main purpose, producing the desired effect for it. Active ingredients are applied for multiple uses including medicine, cosmetics and pesticides to assist with curing an illness, repelling insects or moisturising the skin respectively. For example, the active ingredient in lotion may be glycerin or hyaluronic acid in order to successfully complete its purpose. Active ingredients can only be present for a particular concentration as this can affect the strength and impact of the product, so it can be accommodated for its intended purpose (bannerhealth, n.d.).