Simple Chem. Question (i'm dumb)

[PIAA310]

Ok heres the question

Perfrom the prescribed operations (put answer in sig dig)
21.6mL + 43.57mL + 2mL= 67.17...So what would the answer by in sig dig..my guess is 67 with 4 sig dig. i'm not sure though.

the other question is Put the following in the correct Number of Sig Digs
1.034 (2 sig digs) ___________
739.51 (3 sig digs) __________


Thanks!

[PHF2ATL]

Ok heres the question

Perfrom the prescribed operations (put answer in sig dig)
21.6mL + 43.57mL + 2mL= 67.17...So what would the answer by in sig dig..my guess is 67 with 4 sig dig. i'm not sure though.

the other question is Put the following in the correct Number of Sig Digs
1.034 (2 sig digs) ___________
739.51 (3 sig digs) __________


Thanks!

When you do arithmetic with sig digs, the answer always has the same number of sig digs that the smallest number has in the problem. The answer to the first problem would be 70.

1.034=not sure on that one
739.51= 740. Must have to decimal at the end

[Crazy764]

I haven't done chemistry or significant digits for quite a while, but I believe the first one would be 7.0x10^1. I think that's the correct notation.

[NOTAR520AC]

Ok heres the question

Perfrom the prescribed operations (put answer in sig dig)
21.6mL + 43.57mL + 2mL= 67.17...So what would the answer by in sig dig..my guess is 67 with 4 sig dig. i'm not sure though.

the other question is Put the following in the correct Number of Sig Digs
1.034 (2 sig digs) ___________
739.51 (3 sig digs) __________


Thanks!

For the 1.034, cut the four off & you should have three sig figs- sandwiched-zeros are always significant

Like PHF2ATL said, 740. for the third- decimal must be present or else it's considdered a trailing zero & doesn't count.

Justin

[Messerschmitt Man]

Ok heres the question

Perfrom the prescribed operations (put answer in sig dig)
21.6mL + 43.57mL + 2mL= 67.17...So what would the answer by in sig dig..my guess is 67 with 4 sig dig. i'm not sure though.

[Mungous]

Haven't done this since last year but I'm pretty sure here's how it goes:

67.14 = 4 significant figures (67.00 would be 2 sf)
1.034 = 4 sf
739.51 = 5 sf

It's basically the number of non-zero digits in a number (excluding zeros between two non-zero numbers like 1.034)

What Will said is standard form or scientific notation and is one way of showing significant figures, but seeing as you're not in the thousands or anything it probably isn't worth it.

All addition is rounded off to one decimal place.

For the 1.034, cut the four off & you should have three sig figs- sandwiched-zeros are always significant

Like PHF2ATL said, 740. for the third- decimal must be present or else it's considdered a trailing zero & doesn't count.

Now that confused me. Why do you round it to 1 dp? Also if you cut off the three and four of 1.034 leaving 1.0 you would have 2 sf, since the 0 is accurate. No idea where you got that third figure from .

You would put 740 if it were supposed to be rounded to three significant figures, I think the question is just requires stating how many figures are significant, in which case its 5.

[avro_arrow_25206]

I'm almost certain that 740 only has 2 sig figs, because 0's at the end are not significant.
So if you want 739.51 in 3 sig figs, you should write it as 7.40E2 (7.40x10^2)
The 0's appearing AFTER decimal are significant.

[Crazy764]

Wait, I think I was wrong yesterday.

"2mL" only has 1 sd. Therefore, the answer should only have 1 sd, and the only way to show that is 0.7x10^10.

[PHF2ATL]

I'm almost certain that 740 only has 2 sig figs, because 0's at the end are not significant.
So if you want 739.51 in 3 sig figs, you should write it as 7.40E2 (7.40x10^2)
The 0's appearing AFTER decimal are significant.

If you write 740. with the decimal at the end, the zero is included as a sig fig. It's sandwiched in this case. If it was written as just 740 with no decimal the zero would be trailing and wouldn't count.

[avro_arrow_25206]

If you write 740. with the decimal at the end, the zero is included as a sig fig. It's sandwiched in this case. If it was written as just 740 with no decimal the zero would be trailing and wouldn't count.

Well ok, I guess it would work if they allow you to do "740."

When I learned this stuff, it is either 740, or 740.0 in which case the only way to get 2 sig dig would be 7.4x10^2

[NOTAR520AC]

Now that confused me. Why do you round it to 1 dp? Also if you cut off the three and four of 1.034 leaving 1.0 you would have 2 sf, since the 0 is accurate. No idea where you got that third figure from .

You would put 740 if it were supposed to be rounded to three significant figures, I think the question is just requires stating how many figures are significant, in which case its 5.

Oops- you got me! Pulled my notes- addition is to the least decimal place out of the numbers added. Looks like I don't remember as much as I thought!

I only said cut off the four, equaling 1.03. The sandwiched zero is significant there.

the other question is Put the following in the correct Number of Sig Digs
739.51 (3 sig digs) __________

I hated sig figs- most confusing thing... Always the simple things!

[Mungous]

Ahh I see now what you meant, it was just the way it was worded. Must be seeing things I was sure you said 3 as well