![]() ![]() Sometimes a teacher will have you use 273.0. Follow the policy your classroom teacher sets down. That difference may generate a value for your answer that causes a deduction of points. You may do a calculation on a test (or a web-based assignment) using 273.15 and the answer was done with 273. The ChemTeam occasionally had a student who insisted on using 273.15. So temperatures are usually written just to the tenth place at this introductory level Also, the most common type of thermometer in high school labs is readable to the nearest tenth. This is what is known as an 'idiot indicator.' You do that and your study partner will say "Didn't you learn anything in high school? You're an idiot." The ChemTeam will remain silent as to the reasons.Īlso, never say 'degrees Kelvin.' This value: 225 K is said "two hundred twenty five Kelvins." Please trust the ChemTeam on these points.Įverybody (except you!) in chemistry knows the true conversion value is 273.15, but the decimal portion is usually ignored. Last point: never, ever, use a degree sign on the symbol for Kelvin. If I am saying something different than what your teacher wants you to do, please don't use this phrase (or anything like it) to your teacher: "Well, there's some guy on the Internet who says you're wrong." However, having said that, be careful to watch your teacher's actions in class and ask what the rules are in your class. In reality, the significant figure concept is more complex than the simple rules taught at this level. All examples to follow will use 273.Ī point before going on to some problems: very often in gas law problems it looks like significant figure rules are being violated. Often, the value of 273 is used instead of 273.15. You can convert between Celsius and Kelvin like this: Kelvin = Celsius + 273.15. (The ChemTeam is retired now.) All teachers know this is really fun! OK, back to work. The ChemTeam understands this fully for, you see, this is what happened in his class. Your teacher is doing what he or she is driven to do: confuse poor teenage kids. Sometimes your teacher might put a temperature in the problem, but you really don't need to use it. If you have a Celsius temperature in the problem, you MUST change it to Kelvin, in order to use it in your problem. There are not any gas law problems that the ChemTeam is aware of that use the Celsius temperature directly in the calculation. ChemTeam: Converting between Celsius and Kelvin
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