Use the data in Table 1 to calibrate the buret. MW (KHP) g of KHP Moles KHP = 2. Like most tools used to make quantitative determinations in the laboratory volumetric glassware can and should be calibrated to improve accuracy. Use the Virtual Laboratory to standardize an unknown NaOH solution (approximately 0.2M) to four significant figures via titration with 25.00 mL of a KHP standard solution. Use basic output from an analytical tool (buret) to calibrate that tool. A primary standard is characterized as a reagent of higher purity and is typically a stable solid such that a measurement of mass accurately representative of the number of moles of the standard. Unless otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0. This is critical in successfully conducting both fundamental and applied research as well as quality control measures in various industries. Introduction Sodium hydroxide is hygroscopic and absorbs water from the air when you place it on the balance for massing. Relevance. The NaOH solution is prepared by measuring out about 25 g of NaOH(s), which is then transferred to a 1 L volumetric flask. Use data to perform error analysis (identify the presence of random and/or systematic errors). Using a small funnel, fill the rinsed buret with the NaOH solution above the zero mark as shown in Figure 1. Materials required: pipette filler, volumetric flasks(2-4), beakers(2),small white piece of paper, indicator( 2 drops), conical flask, clamp, soap, eye protection, burette, distilled […] KHP is commonly used as a primary standard because it is a solid at room temperature, is stable in air, and is not hygroscopic, which makes it possible to accurately determine the mass of KHP using a balance. Develop a consensus for the questions in the exercise, Chad Kinney, University of Colorado Pueblo (. Question 1: Explain in layman terms what is meant by the term “concentration” and give examples of common units for concentration in analytical measurements? Please describe the outcome of the calibration process (consider using text, a table and/or a figure to describe the outcome). Question 3: Does the class A buret accurately deliver the measured volume? Moles NaOH = Moles KHP 3. The reaction of KHP with sodium hydroxide is shown below. You are to determine the truemolarity of the NaOH solution to foursignificant figures by titration of a known mass of KHPas specified on the drill sheet. Potassium Hydrogen Phthalate ( referred in the experiment as KHP) was a brittle, white, crystalline substance. V (L) Moles NaOH M NaOH NaOH = 2. For more information contact us at firstname.lastname@example.org or check out our status page at https://status.libretexts.org. Question 2: Why might mass measurements using an analytical balance to measure about 25 g of water be considered more accurate than a volume measurements of 25 mL with volumetric glassware, such as burets or transfer pipets? The NaOH is dissolved by filling the volumetric flask to the mark. Use the buret calibrated in Part 1 and the data in Table 2 to standardize the NaOH solution described in Part 2. Standardization of NaOH Solution At the equivalence point: Moles of KHP = Moles of NaOH Known: Mass of KHP (g) Volume of NaOH used in titration (ml) To be determined: Molarity of NaOH (mole/L) Calculations: 1. After each volume of DI water is delivered the flask the mass of the flask + water is rapidly measured using an analytical balance. NaOH. You can't use the unknown KHP to find the concentration of NaOH as this assumes the KHP is 100% (or close to it). 204.22 g mol-1 V (L) Moles NaOH M NaOH NaOH = 2. 1. Answer Save. As the transparent NaOH solution came into contact with transparent phenolphthalein in the KHP solution, it turned pink which on shaking became transparent.