BS Analytical Chemistry

Lecture 1: Introduction to BS Analytical Chemistry.

Analytical chemistry, as explained by Gary D. Christian in his book, is all about uncovering the secrets hidden within substances. It’s like being a detective for molecules! In this exciting field, we use special tools and techniques to figure out what things are made of, how much of each ingredient they contain, and even how they behave. It’s like solving a puzzle with science. Whether it’s testing the quality of water, finding drugs in a patient’s blood, or making sure your food is safe to eat, analytical chemistry plays a crucial role in our everyday lives. So, if you’re curious and love solving mysteries, Umair Khan Academy guides you to the fascinating world of analytical chemistry.

Lecture 3: Precision and Accuracy

Precision and accuracy are crucial concepts to grasp. Precision refers to how close multiple measurements are to each other when repeated, highlighting consistency. On the other hand, accuracy deals with how closely a measurement aligns with the true or expected value. To put it simply, precision focuses on repeatability, while accuracy concerns correctness. Imagine shooting arrows at a target: precise arrows cluster closely together, while accurate ones hit the bullseye. Both precision and accuracy are vital in science and everyday life to ensure reliable and dependable results.

Lecture 5: Measuring Apparatus BS Analytical Chemistry (Part 1)

It discusses measuring apparatus and their practical applications. Measuring tools are essential devices used to quantify various properties, such as length, weight, volume, and more. These instruments play a crucial role in scientific research, engineering, and everyday life. They help ensure accuracy and precision in measurements, which is vital for experiments, quality control, and manufacturing processes. By understanding how to use measuring apparatus effectively, readers can enhance their ability to make accurate measurements, leading to better scientific discoveries and improved product quality.

Lecture 7: Molarity (A concentration Unit)

Molarity is a vital concept in chemistry that tells us how concentrated a solution is. It’s like measuring how much stuff is dissolved in a liquid. Imagine making lemonade – molarity tells you how many lemons you squeezed into your glass of water. A high molarity means there are lots of lemons (or solute) in the water, making it strong, while a low molarity means only a few lemons, making it weak. Scientists use molarity to mix chemicals accurately, ensuring reactions happen just right. So, it’s like a recipe for chemistry, helping scientists make solutions with the perfect amount of ingredients.

Lecture 9: Molality (A concentration Unit)

Molality is a helpful way to measure how much stuff is dissolved in a liquid, like water, in chemistry. It’s different from other concentration units because it considers the weight of the solvent, not its volume. Imagine making a delicious lemonade; molality tells you how many lemons are in the water, not how much water you have. This makes it great for precise science experiments because it doesn’t change with temperature. So, if you want to make sure your chemistry solutions are just right, molality is the way to go!

Lecture 11: Percentage, ppt, ppm, ppb, pptr (Concentration units)

Simple points for some common concentration units in chemistry are written here. For a brief description watch the lecture.

1. Percentage Composition: Percentage composition tells you how much of each element is in a compound. It’s the percentage by mass of each element in a compound.
2. Parts Per Thousand (ppt): Parts per thousand, or ppt, is a way to express very small concentrations. It means there are 1,000 parts of a substance for every 1 million parts of the whole mixture.
3. Parts Per Million (ppm): Parts per million, or ppm, is another way to express small concentrations. It tells you there are 1 million parts of a substance for every 1 million parts of the mixture.
4. Parts Per Billion (ppb): Parts per billion, or ppb, is an even smaller concentration. It means there are 1 billion parts of a substance for every 1 billion parts of the mixture.
5. Parts Per Trillion (ppt): Parts per trillion, or ppt, is the smallest unit of concentration. It tells you there are 1 trillion parts of a substance for every 1 trillion parts of the mixture.

These concentration units help scientists and chemists describe how much of a particular substance is present in a sample relative to the whole mixture, making it easier to understand and compare different solutions.

Lecture 15 + 16: Solid phase extraction technique.

Solid-phase extraction (SPE) is a widely used method in analytical chemistry to separate and concentrate specific compounds from a liquid sample. It’s like using a special filter to catch the compounds you want.

Apparatus:

1. SPE Cartridges or Disks: These are small tubes or disks filled with a solid material called the sorbent. The sorbent is chosen based on the type of compounds you want to extract.
2. Vacuum Manifold or Syringe: This is used to control the flow of liquids through the SPE cartridge.
3. Collection Tubes: These collect the purified compounds as they are extracted.

Procedure:

1. Conditioning: The SPE cartridge is prepared by washing it with a solvent compatible with the sorbent. This removes any impurities from the sorbent.
2. Sample Loading: The liquid sample containing the target compounds is carefully passed through the SPE cartridge. The sorbent in the cartridge captures the compounds of interest.
3. Washing: Any unwanted impurities are removed from the cartridge by washing it with another solvent. This helps in cleaning the sorbent.
4. Elution: The compounds you want to analyze are then eluted or removed from the sorbent. This is done by passing a different solvent through the cartridge, which collects the target compounds.
5. Evaporation: Sometimes, the eluted solvent is evaporated to concentrate the extracted compounds further.
6. Analysis: Finally, the concentrated compounds are analyzed using various analytical techniques, such as chromatography or spectroscopy.

Solid-phase extraction is a useful technique because it allows you to isolate specific compounds from complex samples, making it easier to detect and quantify them. It’s like using a specialized strainer to separate valuable grains from a mixture of sand and grains.

Remember that the specific sorbent, solvents, and conditions used in SPE can vary depending on the type of compounds you’re working with, so it’s essential to choose the right method for your analysis.

Here are some useful links to further understand the process of SPE and performing experiments.

Lecture 20: Gas Chromatography. (BS Analytical Chemistry)

Gas Chromatography:

Definition:
Gas chromatography (GC) is a powerful analytical technique used to separate and analyze complex mixtures of volatile compounds based on their different chemical properties.

Instrumentation:
GC consists of a few key components: a sample injector, a column filled with a stationary phase, a carrier gas (usually helium or nitrogen), a detector, and a data recorder. The sample is injected into the heated injector, vaporizing it. Then, the carrier gas carries the vaporized sample through the column, where it separates into its individual components based on their interactions with the stationary phase. The detector measures the components as they exit the column, producing a chromatogram that provides information about the composition of the mixture.

Working:
Gas chromatography works by exploiting the differences in the distribution of compounds between the mobile phase (carrier gas) and the stationary phase (inside the column). Compounds that interact more strongly with the stationary phase will move through the column more slowly, leading to separation. The detector records the compounds as they exit the column, producing peaks in the chromatogram that correspond to different compounds in the mixture. By comparing retention times and peak areas, chemists can identify and quantify the components.

Importance of Chemistry:
Gas chromatography is invaluable in chemistry because it allows chemists to:

1. Identify substances in a mixture: By comparing the retention times of known standards to unknown samples, chemists can determine the identity of compounds present.
2. Quantify components: The area under the peaks in the chromatogram is proportional to the concentration of each compound, enabling precise quantification.
3. Analyze complex mixtures: GC is used in various fields, including environmental analysis, pharmaceuticals, food chemistry, and forensic science, for separating and analyzing complex mixtures of volatile compounds.
4. Research and development: It aids in the development of new chemical processes, quality control in manufacturing, and understanding chemical reactions.
5. Drug testing and crime investigations: GC is used to detect drugs, explosives, and other illicit substances, making it an essential tool in criminal investigations.

In summary, gas chromatography is a vital analytical technique that helps chemists separate, identify, and quantify compounds in mixtures, contributing significantly to various fields of chemistry and beyond.