19 posts • Page 1 of 1
Hi! From what I have heard, you should use the amount of decimals given on the periodic table (there is one on the class website) and then round to significant figures at the end of the problem in order to give a more accurate answer.
Hi! I tend to use all of the figures listed on the periodic table for my calculations so that my answer is more accurate, and then I round to the least number of sig. figs. given in the problem (if one of the numbers given only has two figures, I'll round my final answer to two figures as well).
As a general rule for chemistry, whenever there are decimals, it is better to stay true to the original number. For example, hydrogen has a molar mass of 1.008 g/mol (1.00784 g/mol to be exact) and using 1 g/mol instead can have drastic effects in your calculations. I like to keep the number I see on the periodic table and then round to the appropriate sig figs after the calculation.
Hi! I find that it's usually best to use what's given on the periodic table (I've heard from others that we'll be given one for exams?). Usually most periodic tables you find just by looking online have three decimal places but I've found that rounding to two doesn't make that much of a different in the calculations!
Hi! The periodic table I use has 4 digits after the decimal point. What I do is I use the entire number in my calculations. I try not to round while I am working through the problem. I usually keep 4 digits after the decimal point for every value in my calculation. Only at the end do I round my number to the least amount of sig figs given in the values in the question. Hope this helps :)
For the most accuracy, use whatever numbers are given on the provided periodic table. For example, Sapling provides its own periodic table so when completing the homework I would refer to that table only. And we are all given the same table for exams. Hope that helps!
Like everyone else said, it's typically best to use the listed molar mass on the periodic table. Second best option would probably be to round to at least 3 decimals. It's always best to get the most accurate answer we can (but if you are in a timecrunch, rounding elements like hydrogen, carbon, and oxygen to the nearest whole number likely won't affect your answer too much).
What I do is I use the periodic table given by Sapling, and use the correct amount of significant figures given by the problem(always use the least amount of sig figs presented by a piece of the equation). We all use the same periodic table during tests, but generally I would use Sapling as the periodic table on there is a great resource.
I usually use the entire value that's given on the periodic table. This is so that I can get a more accurate answer, avoiding round-off error. Once your final value is calculated you can adjust the answer to the amount of sig figs for that specific problem.
Hi! I usually use the exact value given on the periodic table. For the homework I tend to use the one on sapling so I can use values that they have. However, at the end of the problem I would round the answer to the lowest amount of sig figs in the problem.
Hi, it is usually ideal to use the exact value the periodic table gives you when performing calculations. However, if you do decide to round it to however many sig figs, you should keep it consistent by rounding each value to the same number of sig figs.
Hi!! I have been taught to use the exact values on the periodic table when calculating molar mass. Once I have done all of the calculations, I round my final answer to the number of significant figures that are necessary. This is important to practice because it will help you get the most accurate answer at the end!
I think its best to use the exact value as given to you on the periodic table to get the most accurate molar mass and then you should round it to how ever many sig figs necessary or as indicated in the end. You want to still make sure that your answer is as accurate as possible.
I don't think Lavelle will mind either way, especially since all the interactions and quizzes/tests are multiple choice. But like many others have said, using the most sig figs as possible until you have the final answer is best :)
I find, especially when I'm trying to figure out the empirical formula, that using the entire value makes finding the approximate mole ratio a lot easier. For instance, I was in my discussion earlier and I found that if I used the entire mass without rounding, the mole ratio for the elements in the compound came out to be about 1:5.9, which I can then assume it being 1:6. If I started rounding from the very beginning, my mole ratio would be 1:5.5, which makes it very uncertain whether the ratio should be 1:5 or 1:6. So yes, I generally use the entire value whenever possible :)
Who is online
Users browsing this forum: No registered users and 2 guests