Quantitative analysis focuses on determining the quantity a particular substance (analyte) present in the sample. Quantitative analysis of a sample consists of four main stages: 1. Taking or sampling samples (sampling). 2. Converting the analyte into a dosage form suitable for measurement. 3. Measurement. 4. Calculation and interpretation of measurements. Tools 1. Analytical balance (scales), the requirements for a good balance, are as follows: accurate/thorough, stable and sensitive. 2. Volume measuring instrument In volumetric analysis, the volume measuring instruments that are often used are: a. Turmeric gourd (volumetric flask ) b. Burette, tube-shaped with scale lines like a measuring pipette with the same cross-section from top to bottom. At the bottom it is equipped with a faucet made of glass or Teflon. The capacities often used are 25 and 50 ml, with scale divisions of 0.05 or 0.1 ml. c. Pipettes are divided into two types, namely: 1) volume pipette (volumetric / transfer pipette), often called a goiter pipette in the form of a pipe in the middle there is a round pipe and the top pipe has a circular line as a filling boundary. This pipette is used to take a precise volume of liquid according to the pipette capacity. 2) measuring pipette (graduated / measuring pipette), in the form of a tube with a scale line like on a burette that indicates the measured volume. The zero point is located at the top while the bottom shows the capacity. B. Quantitative Analysis Techniques There are several things below that students need to know when carrying out quantitative analysis so that when carrying out quantitative analysis, accurate and correct results are obtained. 1.Cleanliness a. Keep the table and tools used clean. Provide table napkins, napkins for glassware (brought from home). b. Before use, rinse all glassware with water. Wipe the outside with a napkin until dry but not the inside (unless a water-free titration is performed). How to clean glassware Because volume measuring instruments are only accurate when they are clean, they must be free from oil/fat impurities. Can be tested by pouring distilled water from the device, then the liquid remaining should not be intermittent. To clean fat, detergent can be used/'teepol' , pour the solution into the tool and let it sit for 2 minutes. Or use a saturated solution of 5% potassium bichromate in concentrated sulfuric acid, fill it into the device and leave it for 1 night. Remove the rinse solution with tap water and finally with distilled water then dry, the washing mixture after use is filtered and stored. 2. Neatness a. Return the reagent bottle to its original location if it has been used. b. Do not place the reagent cap on the table but hold it with your left hand. c. All solutions and powders must be sealed to prevent contamination by dirt and other substances. 3. Tagging a. Systematically label all the analyzed solutions, filtrates and sediments (the labels are brought by the students themselves). b. If the vessel contains a liquid other than water, it is marked while the analysis is carried out. 4. Planning a. Before doing the practicum, students understand the instructions on how to work and the principles of determining levels. Provide the tools and reagents that will be used. Plan the main things that need to be done so that the work will run smoothly. b. Do not heat the sample with a scaled glassware because the glass will expand and if it cools again then the volume will not necessarily return to perfect volume. 5. Weighing. a. Use a spoon to collect the substance to be weighed. b. Choose a scale with the right and appropriate capacity. Do not weigh substances beyond the maximum capacity of the scale used. Record the weighing results. Consider the following example of a weighing order: 1)“ Weigh more or less…” meaning: the amount to be weighed cannot be less than90%and cannot be more than110%of the amount to be weighed. 2)“ Weigh carefully…” meaning: weighing deviation cannot be more than 0.1%of the amount weighed. For example, a statement that weighs carefully is 500 mg, meaning that the weighing error limit cannot be more than 0.5 mg. Therefore, weighing must be carried out with an analytical balance with a sensitivity of at least 0.5 mg. Accurate weighingcan also be expressed by adding the number 0 after the comma at the end of the number concerned. For example, the statement weighing 200.0 mg means that weighing must be carried out with a weighing error limit of no more than 0.2 mg. 6. Measurement .You can measure the volume of the solution using a measuring cup, unless otherwise stated in the order”measure carefully…” ,It is intended that measurements are carried out using standard pipettes and must be used in such a way that errors do not exceed the specified limits. Accurate measurements can also be expressed by adding the number 0 after the last comma of the number in question. For example, with a 5.0 ml pipette, the statement states that measurements must be carried out carefully. 7. Use of burette a. Check first whether the burette is in good condition (not broken or leaking), apply just a little Vaseline to the tap so that the drip setting is easy to do. b. Clean the burette before use with water, rinse the burette with a little of the chemical that will be put into it. c. Put the chemical to be used into the burette using a funnel. Fill until the entire burette is filled (pay attention to the bottom!) and there are no gas bubbles in the burette. d. Install the burette on the stand and clamp so that its position is stable and upright e. To read the scale, use black and white paper, hold it behind the burette slightly below the surface of the curved line (miniscus). f. On the buretteSchellbach the inner back wall is outlined in blue on a white ground, the reading being exactly at the sharp part of the blue line. 8 .Buret selection .Perform an orientation titration first using a 50.0 ml capacity burette. Henceforth, in replication titrations, burette selection must be based on the following provisions:A precise measured volume is 20-80% of the burette capacity . So, if the orientation results show a titration volume of 10.0 ml, then replace the next titration with a burette with a capacity of 25.0 ml. 9. How to titrate .The substance to be titrated is referred to astitrate(collected in an Erlenmeyer flask), while the solution used for titration is referred to as titrant(put into the burette). The position of the hand during the titration is shown in the picture below. 10. Titration volume reading.Eyes should be at the same level as the miniscus, use the lower miniscus to determine the titration volume. Don't forget to pay attention to the burette scale, because each burette capacity has a different scale. 11. Determination in duplicate .Perform the determination at least twice. If the suitability of the results is more than 0.4 ml the results cannot be averaged. If the same volume of sample solution is used, the buret readings should not differ by more than 0.05 ml. If these conditions are not achieved, then titration must be carried out again until a difference of no more than 0.05 ml is obtained. 12. Writing significant figures. Significant figures are all the digits in a number (obtained from measurements) that have propertiesdefinite plus one which contains an uncertainty(estimation). Writing measurement results is essentially related to the accuracy of the equipment used. How to write significant figures follows the following rules: a. In general, when writing measurement results there is only one number whose value is uncertain (uncertain), namely the last number. Example: writing the results of macro burette readings on the smallest scale0,1 ml should be written to two decimal places, for example12.65 ml. The number 5 is an uncertain number because it is located between12.60-12.70 ml. b. The number of decimals resulting from addition or subtraction is equal to the factor containing the fewest decimals. c. The number of decimals resulting from multiplication or division is equal to one more digit than that contained in the factor containing the fewest decimals. d. Writing final results that require rounding decimal numbers, then decimal numbers5 or more rounded up, while decimal numbers < 5 rounded down. e. For writing numbers at sample levelsuse 4 decimal places.