Name:Date:Per:
Sources of Error Practice
Let’s take a look at some scenarios. After each one, you will identify what the sources of error might have been. Remember: Sources of error are not mistakes made by the observer or mistakes in calculations; rather they are possible sources of uncertainty found in the procedure. It is not enough to just identify the source of error in the procedure but you must also understand how it might affect the results.
Scenario 1: A group is trying to find the volume of a given liquid. To do this, they are using a graduated cylinder that is measured in milliliters. They pour the substance into the graduated cylinder and take their reading. One group members says there are 25.5 mL. Another group member says its 25 mL exactly and a third group member says they think its 25.6 mL.
What are the 3 possible sources of error for this measurement?
Pick 1 of the sources of error and explain how this affects the results? Would it increase or decrease your data? Explain why.
Scenario 2:A group of students are working on tracking the growth of a plant over an entire month. Each day one member of the group needs to measure the height of the plant and record it in the group’s log book. At the end of the month the group looks at their data and notices that the numbers went up every day except one where the number went down, but then went up again the next day.
What are 3 possible sources of error that would explain this anomaly?
Pick 1 source of error and explain how it would affect the overall data? Would it increase or decrease your data? Explain why?
Scenario 3: You and your lab partner are trying to determine if the temperature of the room affects how quickly a balloon with shrink. Each partner tries the experiment at home and then brings their results back to class to compare the next day. Your lab partner goes to the store and buys a package of brand new balloons, but you already have some balloons at your house that are left over from your sister’s birthday party a month ago so you use those. Both you and your lab partner decide to blow 20 times into a single balloon, tie it off, and measure its size the next morning before school. Your lab partner gets up at 6:00 am the next morning and records that his room was 20 degrees Celsius and the balloon was 35 cm in diameter. You wake up at 7:30 am and record that your room was 65 degrees Fahrenheit and your balloon was 15 inches in diameter. When you get to science class the next day you record the following information into your data table.
Temperature / 20 Degrees / 65 DegreesSize of Balloon / 35 / 15
What are at least 3 sources of error for this experiment?
Pick 1 source of error and explain if it negative or positively impacts the results. Also explain in detail why it would negatively or positively impact the overall results.
Read the following information about a lab and then complete scenario 4-6 based on the given information below:
You and your lab partner are conducting a lab experiment where you are trying to find the % water in a chemical compound. The chemical is placed into a test tube and heated. It will continue to be heated until all the water has evaporated. One you and your lab partner think all of the water has been evaporated you turn off the heat and let the chemical cool. Once it has cooled completely you must then determine the % water in your compound. Hint* to find % water you must take the New evaporated mass (without water) and divide it by the original mass of the whole compound. Then you will have to multiply by 100 to get a percent.
Scenario 4:When you and your lab partner are measuring the mass after heating, some of the compound spills out of the test tube onto the floor.
Does this affect your part or whole? Will it be bigger or smaller?
Will the percent of water falsely increase or decrease? Explain why.
Scenario 5:After heating, you notice that not all of your substance is completely dry. You still decide to take the mass of the compound anyway.
Does this affect your part or whole? Will it be bigger or smaller?
Will the percent of water falsely increase or decrease? Explain why.
Scenario 6:After heating the unknown substance, you notice that some of it turned brown indicating it was burned or too much water had been removed.
Does this affect your part or whole? Will it be bigger or smaller?
Will the percent of water falsely increase or decrease? Explain why.