Rounding off (1 Viewer)

[crammy90]

when doing calculations what decimal place?
i read in the answers you should do your calculations to the same number of decimal points as the question has given. They do this, but they seem to round off/keep the moles as an entirety?
what are your views????????

 

[henry08]

Round off to the number od decimal places for hte least accurate number give nin the question.

 

[appletooth]

I've always been taught to round off using the fewest number of significant figures used in the question, never to decimal places. It's been specified in marking criteria too, and marks can (and have) been deducted for it before. It depends on the question/what markers are looking for.

Also, it's better to round off to more significant figures than fewer, if you're unsure in an exam.

 

[danz90]

Always make sure you round off to the lowest number of significant figures used in the entire question. e.g. if 0.1g is the figure used with the least number of significant figures.. then you must give your final answer accurate to 1 significant figure.

Also.. for pH calculations, significant figures are counted only AFTER the decimal point.. since it is a log function.
for eg. if the limiting sig. figs. in a pH question is 2.. and the pH value you get is 1.65938.. your final answer should be 1.66.

 

[Azreil]

Also.. for pH calculations, significant figures are counted only AFTER the decimal point.. since it is a log function.
for eg. if the limiting sig. figs. in a pH question is 2.. and the pH value you get is 1.65938.. your final answer should be 1.66.

Wow, thank you for sharing I wasn't aware of that.

 

[katie tully]

I always leave about 6 decimal places when doing calculations, and then I round off right at the end. If you round off before, chances are you may be out (although slightly). But that's just how I roll.

 

[always.dreaming]

Unless the question asks me to leave my answer in a particular form, or explicitly asks me to convert it to another, I’ve always written the answer to around 7 decimal places (followed by an ellipsis) and then written under that number the answer to two decimal places.

ie

= m,ttt,hhh.dddddd...

= m,ttt,hhh.dd (2dp)

 

[jest3r]

Always make sure you round off to the lowest number of significant figures used in the entire question. e.g. if 0.1g is the figure used with the least number of significant figures.. then you must give your final answer accurate to 1 significant figure.

QFT. If you go on to do chem subjects at uni, they're really pedantic about sig figs, and this is the method that they drill into our heads.

 

[danz90]

Wow, thank you for sharing I wasn't aware of that.

lol you know... if you don't round off to correct sig. figs. in a calculation question in the HSC Chem exam.. its IMPOSSIBLE to get full marks for that question.

 

[Pwnage101]

lol you know... if you don't round off to correct sig. figs. in a calculation question in the HSC Chem exam.. its IMPOSSIBLE to get full marks for that question.

says who