CHEM 101L Pre-Lab 1 Fall 2021 Name UNC onyen Experiment 1: Mass Volume and Density Pre-Lab Assignment Instructions : 1. When answering questions, do not repeat or copy from the lab manual. You are encouraged to use the Lab Manual as a reference, but plagiarized answers will not be graded. 2. Do not ever work to answer these questions with a partner - avoid plagiarism and cheating. 3. Do not exceed the limit given for each question. 4. Do not remove instructions or any bolded text. 1. (2) What is the objective of this lab (what are you measuring and why)? (1-2 sentences)The objective of this lab is to accurately and precisecly measure the density of different water samples.Students will also determien the effectiveness of water purification devices, while also observing the effects of temperature on density. 2. (3) Summarize this experiment: Provide a list of tasks for this experiment, using 1 phrase or sentence per number. You can use a maximum of 4 points to describe Experiment 1. 1. Place empty beaker on scale, weigh mass of buret segment and largest volume increment 2. Pour 5mL water into burret, record initial volume, then clamp buret segment in beaker to hot plate 3. Turn on hot plate and set up Vernier temperature sensor. record volume of water with a temperature probe 4. Record initial temperatuer of water, turn off hotplate when it gets to 80 degrees Celsius, and continue recording the temperature and volume until you obtain 5 measurements 3. (2) Look up and reference the SDS (Safety Data Sheet) (you can use any resource) for iron (II) sulfate (FeSO4) and calcium hypochlorite (Ca(ClO)2). Report the the National Fire Protection Association (NFPA) ratings for each compound and explain the significance, one potential hazard and one prevention method for both compounds below. o Iron (II) sulfate (FeSO4) Health hazard rating: health 2, flammability 0, instability 0 Potential health hazard: may explode if heated under pressure, can cause skin irritation Preventions: wear protective gloves/clothing/eye protection Significance: Without proper PPE, skin and eye irritation will occur, and may cause liver and kidneey damage. Animal studies have also reported the development of tumors.CHEM 101L Pre-Lab 1 Fall 2021 o Calcium hypochlorite (Ca(ClO)2) Health hazard rating: health 3, flammability 0, instability 1 Potential health hazard: strong oxidizer which may ignite combustibles, may cause severe injury and burns Prevetions: Keep away from heat, wear proper PPE attire Significance: failure of proper PPE atire can cause eye and skin burns; ingestion or inhalation may also cause severe damage to digestive tract and chemical burns to respiratory tract. 4. (2) If the mass of your sample remains the same, but your volume increases, how does this influence the density of your sample? (1 phrase/sentence) The density will decrease, as volume is the denominator in the formula to find density. 5. (2) Consider each of the samples of water used in this experiment. Why should you anticipate that these samples will have different densities? (1 sentence) The density is effected by not only temperature, but salinity as well, and the contaminated sample of water may have substances dissolved in the water that can change the sample's mass. 6. (2) In this experiment, why is the mass of the burette segment with water measured twicefor each sample; once before and once after heating? (hint: What potential error or uncertainty is being accounted for?) (1-2 sentences) One reason that the burette segment was measured twice was to be as precise as possible. Another reason was to measure if the water mass has changed due to evaporation during the heating process. 7. (2) Why should the water in the buret segment be below the level of water in the 600-mL beaker? (1 phrase/sentence) This is to make sure that all of the boiled water surrounds the buret segment.CHEM 101L Pre-Lab 1 Fall 2021 8. (2) Why do we move the hot plate and beaker and not the buret segment once the temperature reaches 80 degrees? (1 phrase/sentence) To ensure accuracy and precision within the buret segment. 9. (2) What are the SI units for density? (units only) Kg/m^2 10. (2) What is the advantage of pooling your data with the rest of the section? Data pooling will develop a more accurate result as it has a larger sample of experiments and have an easier time in identifying issues such as errors and differences between datas. 11. (6) The following data represents 3 series of measurements of the density of water. The literature value for the density of water is 1.00 g/mL. Use Excel to calculate the mean, standard deviation and CV of each data set and copy the values into the table provided, then answer the questions below. (find the formula for CV in the Lab Manual) Data A (g/mL) Data B (g/mL) Data C (g/mL) 1.01 1.65 1.50 1.05 1.68 1.13 1.03 1.61 2.89 1.06 1.59 4.12 1.09 1.67 1.19 Data A (g/mL) Data B (g/mL) Data C (g/mL) Mean 1.05 1.64 2.17 Standard Deviation 0.030 0.0387 1.30 CV 2.86 2.36 59.9 a. (1) Which data set is the most precise? (A, B, or C) B, as it had a smaller coefficient of variation than the rest of the two data sets. b. (1) Which data set is the most accurate? (A, B, or C)CHEM 101L Pre-Lab 1 Fall 2021 A, as it has the closest mean number to the literature value density of water, which is 1.00. Significant figures provide important information regarding the precision of instruments used inan experiment. It is essential that we relay the correct number of significant figures when reporting values. If we perform mathematical functions, such as addition/subtraction or multiplication/division, the number of significant figures could change depending on the function and significant figures present in each value. 1. (4) Provide the solution to the following calculations using the correct number of significant figures: a. 6.24 + 8.016 = b. 0.89 x 1.24 = c. 5.555 - 5.5 = d. (10.001 - 9.965) / 321.75 = Note: You may want to refresh your understanding of the rules for significant figures by reviewing your textbook or notes from the CHEM 101 Lecture course. 1. (2) Report the measurement you obtain using the scale below. Remember to use the correct number of significant figures. TA ONLY: Late Penalty Formatting 16.2 14.26 1.1 0.055