Within chemistry there is a wide use of numbers that are used to describe a measurement of a substance, distance, or object. There is accuracy that is necessary to properly measure these various quantities. The precision is dependent on the particular instrument that was used to produce the measurement. For example, the analytical balance that is used in Chemistry 180 measures mass in grams to the thousandths place. It is known by scientists that quantities from instruments that produce more numbers are considered to be more precise, and quantities with less numbers are not. Therefore, the analytical balance that provides a measurement to the thousandth of a gram has greater accuracy than an analytical balance that measures only to the tenth
Specifically, significant figures are defined as the values in a measurement that are non-place holding. There are various rules to ensure that correct number of significant figures are given in a measurement. The rules state that numbers that are always significant include nonzero numbers, zeros between nonzero numbers, zeros preceding a decimal point, and zeros following a decimal point. However, numbers that are not considered significant are the leading zeros that are before the first nonzero number. Finally, values without a decimal point that end in a zero are considered ambiguous, but to avoid confusion of the significant figure count scientific notation should be used. Using the previous rules provided it is obvious that the value 0.000924350 has precisely six significant figures. Significant figures describe the quality of a measurement, and the quality of a measurement is dependent on the number of significant figures. There are also significant figure rules when dealing with addition, subtraction, multiplication, and division. It is important to correctly present the significant figures because it has an important meaning to each
... while weighing the reactants would try and avoid letting the reagents get in contact with apparatus that may not be necessary so as to avoid loss of some the substance and this way the exact mass would be achieved.
In this experiment, there were several objectives. First, this lab was designed to determine the difference, if any, between the densities of Coke and Diet Coke. It was designed to evaluate the accuracy and precision of several lab equipment measurements. This lab was also designed to be an introduction to the LabQuest Data and the Logger Pro data analysis database. Random, systematic, and gross errors are errors made during experiments that can have significant effects to the results. Random errors do not really have a specific cause, but still causes a few of the measurements to either be a little high or a little low. Systematic errors occur when there are limitations or mistakes on lab equipment or lab procedures. These kinds of errors cause measurements to be either be always high or always low. The last kind of error is gross errors. Gross errors occur when machines or equipment fail completely. However, gross errors usually occur due to a personal mistake. For this experiment, the number of significant figures is very important and depends on the equipment being used. When using the volumetric pipette and burette, the measurements are rounded to the hundredth place while in a graduated cylinder, it is rounded to the tenth place.
This is due to the small changes in mass. The values are only significant with more decimal places, but cannot be shown on the electronic balance. As a result, the machine rounds off the values when they overreach the range of the
Introduction: SI units and English units are a very important part of measuring around the world. English units, which are inches, is the most common unit of measure in America. SI units, which are centimeters, are most commonly used in Europe. These units can help us measure many things such as the length of a book or a piece of wood. In this lab, we had to determine the length of 10 lines in inches and in centimeters. We did this so we can find the slope of our measurements and to find the percent error. Percent error is a statistic that is used to determine how far an observed value deviates from the true value. The formula for percent error is the absolute value of the observed value (the value you get when conducting the experiment) minus the accepted value (which is the value that we already know) over the accepted value multiplied by 100. This lab also gives us a better understanding on how to measure using SI and English units and why they are important.
In stoichiometry and this lab, proportions or mass ratios are used to find the quantitative relationships between the reactants and products. Another topic that relate to this lab is the limiting reaction. Stoichiometry was used to find the limiting reaction of this reaction lab through proportions and conversions, which was lead (II) nitrate. Additionally, the excess reactant is another topic that relates to this lab. Stoichiometry was used to find the excess reactant which was potassium iodide. Another topic mentioned was the actual yield. The actual yield was used for lead (II) iodide. This data can be compared to the theoretical yield to find how well the experiment was performed. Additionally, the theoretical yield was used in this lab in order to find the percent yield. Another topic was the percent yield. The higher the percent yield, the better the experiment was performed. Another topic was double replacement. In the experiment the reactants are made of two elements that yields products which have been double replaced. In addition to the previous topics, uncertainty is another topic repeatedly used throughout the lab. The uncertainty is used during measurements to account for the room of error that was possibly made during the measurements. Molar mass was another topic that relates to the lab. In the proportions and conversions part of the lab, molar mass is used to correctly balance the
Calculations are used with measurement to perform many of auto technicians’ duties. When performing a valve adjustment, the valve lash is measured using a feeler gauge. A feeler gauge is a piece of metal precision ground to an exact thickness. The lash measurement compared to the lash tolerance, if the lash is out of tolerance; is the measurement to large or too small. If the current lash value is too small, you have to calculate how much larger of a shim needs to be installed to bring the measurement within specifications. The valve shim that is used to adjust lash is removed and measured, the amount of adjustment is calculated and the proper size shim is installed. The lash is than rechecked to verify calculations and proper valve clearance. If any of your measurements or calculations are not done correctly this can be a long process, and the job only pays a predetermined hour amount, if it takes you longer than that time, you are working for free in most cases. Calculations are also involved in rebuilding an engine; the journals of a crankshaft are measured for their outer dimension, then the webs of the block are measured for their inner dimension, these dimensions are read into a chart that helps to determine the proper bearing size to go into the engine assembly to give the proper oil clearance. If your measurements and calculations are incorrect; the engine will have not enough oil clearance the bearings will over heat and
To properly complete this lab, a basic understanding of mass, moles, and empirical formula is required. Mass is a unit of measurement that is used to determine the number of grams in a certain object. A mole is a measurement in which the amount of substance that is present can be determined.To convert between from mass to moles the amount of grams present is divided by the atomic mass to find moles. To get back to mass from mols the amount of mols is multiplied by the atomic mass. An empirical formula is a chemical equation with the simpliest positive ratio possible. To find an empirical formula the elements in the formula must be in moles. Then the smallest amount of moles is used to divide all the other mole numbers. These numbers
In order for a set of data to be accurate, there needs to be another set of data from prior researchers that was concluded to be the only correct rate at which a birthday candle burns. Also, the data from this experiment cannot be identified as being precise, because if this experiment were to be repeated, due to the experimental error, the results would not be exact from the first time the experiment was performed. The first most important step of the procedure for data collection is the time that was recorded after lighting the candle. The time was important, because time was a factor in determining the answer to the experimental question, which was the rate at which the candle burns. Recording the time accurately is significant to the final results, because if the time was not recorded in this experiment, it would be impossible to answer the experimental question. The second step that contributed to data collection was the massing of the candle. If it wasn’t done properly, the rate of the burning candle would have been slightly off. These two steps were the most important in gathering the data, because the time and the mass were both needed in order to calculate the
Krueger, L. E. (1984). Perceived numerosity: A comparison of magnitude production, magnitude estimation, and discrimination judgements. Perception and Psychophysics, 35(6), 536-542.
The Gravimetric Stoichiometry lab was a two-week lab in which we tested one of the fundamental laws of chemistry; the Law of Conservation of Mass. The law states that in chemical reactions, when you start with a set amount of reactant, the product should theoretically have the same mass. This can be hard sometimes because in certain reactions, gases are released and it’s hard to measure the mass of a gas. Some common gases released in chemical reactions include hydrogen, carbon dioxide, oxygen and water vapor.
- Each teaspoon may not have been equal. Measurements were made based on judgment and not exact measurements.
0.000 7 63 106 55 74.7 1.245 9 70 135 90 98.3 1.638 11 85 135 70 96.8 1.613 [ IMAGE ] [ IMAGE ] Conclusion = = = =
how much there is, and numbers tell you how many there are. This is cause for
substance which can add up to a small margin of error leading to a huge potential for false
Currently, people of many countries use this SI unit for measurements. The meter is used for measuring length (it can be converted to millimeters, centimeters, decimeters, kilometers, decameters, and hectometers). The liter is used to measure volume and its conversions are similar to the meter conversions. The gram is used to measure mass and its conversions follow the meter’s conversions as well. Scientists from all over the world make sure of they use this metric system in order to communicate data and make all calculations simpler. Although a vast majority of world uses the metric system in daily activities, the United States, UK, and other countries decide to still use English units daily. And even though everyone in the world may use different measurements daily, it was all created to make our lives a little simpler each day.