Safety of Chemicals Past Paper PDF

)‫(ملخص إمتحان النهائي – العملي‬ (Safety of Chemicals) Material Safety Data Sheet (MSDS): is a document that contains detail of hazards associated with a chemical and gives information on its safe use. Personal Protective Equipmen...

)‫(ملخص إمتحان النهائي – العملي‬ (Safety of Chemicals) Material Safety Data Sheet (MSDS): is a document that contains detail of hazards associated with a chemical and gives information on its safe use. Personal Protective Equipment (PPE): required when entering a laboratory such as lab coat, safety glasses and enclosed footwear. Q: Who is the first person to inform him if you made incident? Answer: First person to inform is Laboratory assistant. Q: What must you do if you want to work after office hours? Answer: A. ❖ Advise your supervisor or laboratory assistant. B. ❖ Must be accompanied by another student (buddy). C. ❖ Follow the instruction set out in laboratory working after office hours procedure. D. ❖ Follow the approved standard operation procedure (SOP) and risk assessment (RA) for your experimental procedure. Q: What must the label include? Answer: 1. Name of all the chemicals and its compositions 2. Date of the first chemical added into the container. 3. Your name and the laboratory where you produce the waste. 4. Proper PPE is needed to handle the chemical waste. Q: What must do if you have hazardous waste in your laboratory? Answer: Make sure the hazardous waste is labelled properly Inform the lab staff to store waste and can guidance from them Store the waste into their category. Make sure the container is sealed properly. Q: If you spill chemicals on the laboratory floor, what do you need to do? Answer: o Do not panic. o If the spill contacts your skin, rinse it immediately with running water. o Report to the lab staff about the spill. Personal Protective Equipment (PPE): includes safety glasses, lab coat, gloves, long pants, closed top shoes (enclosed footwear). Q: What is the purpose of using hood or fume hood? Answer: The fume hood is used for the safety of reactions. Q: What is the best practice when you order chemicals? Answer:  Plan your work: discuss with supervisors.  Check chemical inventory.  Only order the amount that you need.  Buy less hazardous. Q: What should be included in an Emergency Response Plan (ERP)? Answer: Emergency contact numbers Evacuation plan Floor layout Emergency equipment PPE (Titration) Titration: is a laboratory technique used to determine the concentration of a solution by reacting it with a known volume and concentration of another solution, with which it reacts until exact chemical equivalence is achieved (the equivalence point). Q: What does the titration process include? Answer: This process involves the gradual addition of one solution (the titrant) to another solution (the analyte) until the reaction between the two is complete. Analyte: The solution of unknown concentration but known volume put in conical flask. Titrant: The solution of known concentration put in burette. Equivalence Point: The equivalence point is the point at which the amount of titrant added to the amount of analyte present. At this point, the reaction is complete. The equivalence point determined in a strong acid-strong base titration always occurs at pH=7. End Point: It is a practical point at which the reaction is observed to be complete, this point is usually observed with the help of indicator. The endpoint of the titration is the point at which the colour changes. Acid-Base Titrations: depend on the neutralization between an acid and a base when mixed in solution. The acid-base indicator indicates the endpoint of the titration by changing color. Redox Titrations: is a laboratory method of determining the concentration of a given analyte by causing a redox reaction between the titrant and the analyte. Precipitation Titrations: is a type of titration which involves the formation of precipitate during the titration technique. Complexometric Titrations: is a form of volumetric analysis in which the formation of a colored complex is used to indicate the end point of a titration. Q: What is the purpose of burette using? Answer: It can be used for titrant solution. Q: What is the purpose of pipette use? Answer: It can be used for analyte solution. Q: What is the purpose of conical flask using? Answer: It can be used for analyte solution. Q: What is the pH indicator? Answer: Add a few drops of an appropriate pH indicator to the analyte solution in the flask. Common indicators include phenolphthalein (for acid-base titrations) or bromothymol blue. (pH Meter) A pH meter: is a precise instrument that weighs the hydrogen-ion. movement in water-based suspensions, showing its acidity or alkalinity. expressed as pH. Q: Why is a pH meter called as a “potentiometric pH meter”? Answer: because it measures the variation in electrical potential between a pH electrode and a reference electrode. pH electrodes: which are analytical sensors, are used to measure the potential of hydrogen (pH), or the negative logarithm of the hydrogen ion activity, in a solution.  )‫)مالحظات إضافية‬ If the H+ density is higher than OH-, the substance is acidic, i.e., the pH amount is less than 7. If the OH- density is higher than H+, the substance is basic, including a pH value higher than 7. If identical quantities of H+ and OH- ions are present, the substance is neutral, with a pH of 7. The Reference Electrode: contains a neutral solution such as Potassium Chloride solution with a fixed concentration and gives a stable voltage. Measuring Electrode: depends totally upon the pH of the suspension. Liquid Junction: is known as the overall potential or the voltage. Q: What happens when the two Electrodes are immersed in the Sample Suspension? Answer: The Hydrogen ions flow towards the outside surface of the Measuring Electrode and displace some of the metal ions within it. Q: Where does Ion-exchange take place? Answer: Ion-exchange takes place on the interior surface of the Glass Electrode from the sample suspension and generates a potential variation (Hydrogen- ion activity) among them. Q: Why must the temperature of the solution be 25 °C when we use the pH, Meter? Answer: Because, with this temperature, we can get the right pH reading. Q: Why must we wash the electrodes with distilled water? Answer: If we do not wash the electrodes with distilled water, we are unable to get the right pH reading. Q: What is the output of the Impedance Voltmeter? Answer: The output of the Impedance Voltmeter is Voltage studies, and it possesses to be calibrated to prepare precise pH Measurement. Types of pH Meter: Based on the types of requirement pH meter is divided into several classes such as: 1. Based on portability: Portable pH meter: the use of compact DC power equipment. Desktop pH meter: Same as Portable pH meter  Pen pH meter: normally composed of a single scale, conventional measurement range, easy and handy equipment. 2. Based on purpose: Laboratory pH meter: multi-function, high accuracy. Industrial online pH meter: excellent stability, steady work, a specific level of measurement efficiency, environmental flexibility. 3. Based on advanced level: Economic pH meter. Intelligent pH meter. Precision pH meter or digital pH meter. Types of Electrodes: Three types of pH electrodes: 1) Glass electrode. 2) Reference electrode. 3) Combination gel electrode. Advantages of pH Meter: 1) pH Calibration is low-priced and robust. 2) Pocket size pH Meters are user friendly. 3) Accounts are reliable and specific. Disadvantages of pH Meter: 1) Heat affects the output readings. 2) pH Calibration utilizing glass electrodes needs to be clean as deposition on the electrodes influences the reading. (Devices & Equipment in the laboratory) Electric Centrifuge: A centrifuge is a mechanical or electromechanical device used to separate various components of a liquid. It achieves that by simulating a very high gravity environment inside the tubes by producing centrifugal forces by spinning very fast. Purpose of Electric Centrifuge: A centrifuge is used to separate particles suspended in a liquid according to particle size and density, viscosity of the medium, and rotor speed.