Sig Fig HELP!

[zz980111]

We round off numbers by the least number of sig fig in the calculation. however, if I divide a number of mole by molar ratio in a equation which cant be inaccurate, for example 2, do I round the answer off to 1 sig fig?
And also I've heard from others that you always keep 3 sig figs for the answer, is it true?

[jyodesh.com]

We round off numbers by the least number of sig fig in the calculation. however, if I divide a number of mole by molar ratio in a equation which cant be inaccurate, for example 2, do I round the answer off to 1 sig fig?
And also I've heard from others that you always keep 3 sig figs for the answer, is it true?

A number that has no uncertainty associated with it, is assumed to have infinite sigfigs. so like 1.0 moles of H2 has 2.0 moles of H not 2
You do not always keep 3 sig figs for the answer. 3 sig figs is just really common because a lot of the constants that you use are given to 3 sig figs in the data book.

[zz980111]

A number that has no uncertainty associated with it, is assumed to have infinite sigfigs. so like 1.0 moles of H2 has 2.0 moles of H not 2
You do not always keep 3 sig figs for the answer. 3 sig figs is just really common because a lot of the constants that you use are given to 3 sig figs in the data book.

Well then I have a questions here

100g of NO gas which is 30.0g/mol, since 100g is only 1 sig fig, I calculated 3 mol of NO gas and use it for further calculations which then result in only 1 sig fig in the answer. I asked the teacher and she said that you should leave around 3-4 sig figs during the calculation. Does it mean that I did wrong and sig fig rule don't apply during the calculation but just the answers? Or I did right?

I've seen other values like 30g , do I just use 1 sig fig since it didn't say 30. g?

Thank you very much!!

[IndefatigableLover]

Well then I have a questions here

100g of NO gas which is 30.0g/mol, since 100g is only 1 sig fig, I calculated 3 mol of NO gas and use it for further calculations which then result in only 1 sig fig in the answer. I asked the teacher and she said that you should leave around 3-4 sig figs during the calculation. Does it mean that I did wrong and sig fig rule don't apply during the calculation but just the answers? Or I did right?

I've seen other values like 30g , do I just use 1 sig fig since it didn't say 30. g?

Thank you very much!!

100g is three significant figures and not one significant figure... 30g is two significant figures as well.

Firstly, do all your calculations with infinite amount of significant figures before answering and when you're answering, round to the nearest significant figure.

For some rules, you can check here: http://chemistry.bd.psu.edu/jircitano/sigfigs.html

[zz980111]

100g is three significant figures and not one significant figure... 30g is two significant figures as well.

Firstly, do all your calculations with infinite amount of significant figures before answering and when you're answering, round to the nearest significant figure.

For some rules, you can check here: http://chemistry.bd.psu.edu/jircitano/sigfigs.html

Thanks! Using infinite sig figs during the calculation makes sense to me.
I think 100g is 1 sig fig according to the rule which says any trailing zeros in the DECIMAL PORTION are significant. 

And also, how hard do you think specialist is in yr12 comparing to methods 34? 

[IndefatigableLover]

Thanks! Using infinite sig figs during the calculation makes sense to me.
I think 100g is 1 sig fig according to the rule which says any trailing zeros in the DECIMAL PORTION are significant. 

And also, how hard do you think specialist is in yr12 comparing to methods 34? 

I'm fairly certain that 100g is 3 significant figures as if it were 1 significant figure, then it would be 1 x 10^2 (which would be one significant figure however the zeros before the decimal are significant).

I'm not too sure how much will be changed with the new study design but I personally find it an interesting subject with the jump from Methods to Specialist to be varied for people however the course for Specialist is significantly less than Methods and there's plenty of overlap with the algebra and calculus to some extent which will help with Methods. Overall, it's a struggle for some but I've known plenty of others who have gotten higher RAW scores in Specialist compared to their Methods score so it might not be out of reach!