Which of the following represent a systematic error when measuring the mass of an anhydrous object? Anhydrous means that the object has been completely dried out. All the water has been left out of the object or evaporated out of the object. Now when it comes to a systematic error, it's predictable in the sense that it's always going to give us a value that's too high or too low from the agreed upon value. But in its predictability, there is some problem involved. Because of this predictability, if I have the agreed upon value ahead of time, which is called your theoretical value, I cannot know for sure if a systematic error is occurring without that value. A good thing about systematic error is if you know that you have it, all you have to do is correct the design of your experiment. By correcting it, you can eliminate that error. Knowing this now, let's take a look at the options:
- You weigh the object before all the water has evaporated. So you're weighing an object, it's supposed to be completely dry, but you haven't given enough time to dry out. So you're going to get a mass that's too high. This is a flaw within the experiment. You didn't wait long enough for you to dry out all of the water. So this is definitely a systematic error. All you have to do to correct it is wait more time. Always wait as long as possible in terms of drying. Get all the water out, and then you'll get the right mass of the dry object.
- The scale used has not been properly calibrated. So this is a big thing. Anytime you start a lab, they always tell you to calibrate your pipettes, calibrate your burettes, calibrate your scales. This ensures that the number that you're going to get is as close to the agreed upon value as possible. So again, that's another flaw within the system. All you have to do to get rid of that error is calibrate the scale.
- Airflow near the balance causes the precise mass to vary. Airflow is hard to control as you're opening up the scale and putting your object inside and then closing the door behind it. So airflow is something that's outside your realm of control. Because of this, it's a random error. That airflow won't always be present so it won't always affect the mass that you have.
- You write down the incorrect mass of the anhydrous object. So here, you didn't write down the correct number. This is a little bit tricky. Could this be a systematic error? Could this just be a random error on your part? Because you're not always going to write down the wrong number, we're going to say here that this could fall under a systematic error because within the design of your experiment, you're supposed to always double-check, triple-check all your numbers and values to make sure they make sense. The fact that you wrote down the wrong number and didn't go back and check it is a flaw in the design of your experiment. You tell yourself, if I write down a number, I have to look at it multiple times to make sure it's the correct number that I'm writing. So we could say that the 4th option would fall under systematic error as well. So here we'd say that 1, 2, and 4 are your systematic errors, although 4, you could be open to saying that it's a random error as well because you're not always going to make that mistake. So, guys, remember the difference between systematic
